Geryonid Crabs and Associated Continental
A Research Workshop Report
William J. Lindberg and Elizabeth L. Wenner
South Carolina Sea Grant Consortium
Technical Paper No.58 January 1990
Technical Paper No. 58
GERYONID CRABS AND ASSOCIATED CONTINENTAL SLOPE FAUNA:
A RESEARCH WORKSHOP REPORT
William J. Lindberg
Department of Fisheries & Aquaculture
University of Florida
Elizabeth L. Wenner
Marine Resources Research Institute
South Carolina Wildlife and Marine Resources Department
Sea Grant Project No. R/LR-B-17
Grant No. NA86AA-D-SGO68
Technical Paper 58
Florida Sea Grant College
in cooperation with
NOAA National Undersea Research Center,
University of North Carolina at Wilmington
The South Carolina Sea Grant Consortium
Considerable research in recent years has been invested in
the basic biology, ecology, and fisheries of deep-water crabs,
Family Geryonidae. These efforts have been concentrated off the
southeastern United States and southwest Africa, following earlier
work from the Mid-Atlantic states of the U.S. to the Canadian
Maritime Provinces. Species of primary interest have been the
golden crab, Chaceon fenneri, and the red crabs C. maritae and C.
auinauedens. Only a fraction of recent data has been published.
Yet, the many investigators and sponsoring agencies sought to
foster regional comparisons, to inform the commercial fishing
industry and resource agencies, and to provide guidance for future
On January 19 and 20, 1989, an invited panel of scientists,
fishermen, and Sea Grant Extension faculty met in Tampa, Florida
to share their results, conclusions, and latest hypotheses. This
report, as a summary of workshop presentations and discussions, is
simply a vehicle by which that expertise can be delivered to a
broader audience. In due time, the data summarized here should
appear in the primary literature. Meanwhile, persons needing
greater detail are encouraged to communicate directly with
This international workshop was possible only through the
generous sponsorship of several agencies and institutions
acknowledged on page iii. We are particularly grateful for the
administrative leadership and financial support provided by Alan
Hulbert and the National Undersea Research Center, James Cato and
the Florida Sea Grant College Program, Margaret Davidson and the
South Carolina Sea Grant College Program, and Hugh Popenoe and the
International Program of the Institute of Food and Agricultural
Sciences, University of Florida. Workshop arrangements were made
by Twila Stivender and Monica Lindberg, much to the relief of the
workshop co-chairmen, and the report was prepared for publication
by Margaret Lentz and Karen Swanson of the South Carolina Wildlife
and Marine Resources Department.
Ultimately, credit for this workshop's success belongs to the
attendees for their enthusiastic participation. We very much
appreciated the collegial exchanges, critical comments, and good
humor. Much remains to be learned about these crabs, and about
the ecology of the upper continental slope in general. It is our
hope that continued research will give cause for a similar
gathering in the not too distant future.
W.J. Lindberg and E.L. Wenner
National Undersea Research
Center/University of North
Carolina at Wilmington
South Carolina Sea Grant
Private Donations through the
School of Forest Resources &
Conservation, University of
Department of Fisheries and
Aquaculture, University of
National Museum of Natural
Halifax Fisheries Research
Laboratory, Department of
Fisheries and Oceans, Canada
Department of Biology,
Rochester Institute of
Gulf Coast Research Laboratory
Horn Point Environmental
Laboratory, University of
Department of Biology,
University of South Florida
School of Fisheries,
University of Washington
Florida Sea Grant College
Institute of Food and
University of Florida
South Carolina Wildlife
and Marine Resources
Florida Sea Grant
Extension Program and the
Sea Fisheries Institute,
Georgia Sea Grant
Institute, University of
Connecticut at Avery Point
Department of Marine
Sciences, University of
Department of Natural
Maryland Sea Grant
TABLE OF CONTENTS
Preface . . . ..... ... ii
Workshop Sponsors . . . . ... .. .iii
Studies on Systematics of Geryonid crabs. R.B. Manning.... 1
Animal-Sediment Relationships Involving Red Crabs (Chaceon
quinauedens) on the Southern New England Upper Continental
Slope. R.B. Whitlatch, J.F. Grassle, L.F. Boyer, and
R.N. Zajac . . . . ... . .. 3
Distribution and Abundance of Golden Crab, Chaceon fenneri,
in the South Atlantic Bight. E.W. Wenner . . 6
Patterns of Population Structure and Abundance for Golden
and Red Crabs in the Eastern Gulf of Mexico. W.J. Lindberg,
F.D. Lockhart, N.J. Blake, R.B. Erdman, H.M. Perry, and
R.S. Waller . . . . . 8
Chaceon maritae Studies off South West Africa.
R. Melville-Smith . . . . . 10
Fecundity and Reproductive Output in Chaceon fenneri and
C. quinauedens. A.H. Hines . . . . 12
Annual Reproduction in Deep- ea Brachyuran Crabs
(Chaceon spp.) from the Southeastern United States.
R.B. Erdman, N.J. Blake, H.M Perry, R.S. Waller,
W.J. Lindberg, F.D. Lockhart . . . 14
Reproduction in Male and Female Chaceon. G.W. Hinsch 16
An Assessment of the Georgia Golden Crab Fishery.
D. Kendall . . . . . 18
Respiratory and Cardiovascular Physiology of
Chaceon fenneri and C. auinqUedens in Normoxia and Hypoxia.
R.P. Henry, H.L. Handley, A. Krarup, and H. Perry . 20
David A. Armstrong . . . . 23
Anson H. Hines . . . . ... 30
Edited Group Discussion Transcripts . . . 39
Summary of Research Needs and Opportunities . . 52
Literature Cited . . . . .. 55
Appendix: Workshop Participants . . ... A-i
STUDIES ON SYSTEMATICS OF GERYONID CRABS
Raymond B. Manning'
Geryonid crabs are true deep-water crabs that are found in
all oceans except in the eastern Pacific above Chile. They occur
in depths from about 100 to more than 2800 meters.
Studies on the geryonids have revealed that the family
comprises three genera: Gervon proper, with three anterolateral
teeth on the carapace, containing two species restricted to the
northeastern Atlantic and Mediterranean: G. trispinosus (Herbst)
(= G. tridens (Kroyer)) and G. loncipes (A. Milne Edwards).
Although these are relatively small geryonids, with maximum
carapace widths of about 10 cm, they are fished commercially.
Two new genera, Chaceon and Zariquievon, both with five
anterolateral teeth on the carapace, have been recognized in the
family. Zaricuievon containing one small species from ca. 2800
meters in the western Mediterranean, was named for R. Zariquey
Alvarez. Its size, width about 2 cm, shape, and inflation of the
carapace distinguish it from the other geryonid genera. The second
new genus, Chaceon, was named for Fenner A. Chace, Jr., and
contains all of the species now placed in Gervon that have five
anterolateral teeth on the carapace. It includes 11 named species
previously placed in Gervon, G. affinis (A. Milne Edwards &
Bouvier), northeast Atlantic; G. chuni (Macpherson), Namibia and
South Africa; G. erytheiae (Macpherson), Valdivia Bank; G. fenneri
(Manning & Holthuis), west Atlantic; G. aranulatus (Ingle), west
Africa; G. cranulatus (Sakai), Japan; G. inghami (Manning &
Holthuis), Bermuda; G. macphersoni (Manning & Holthuis), southwest
Indian Ocean and South Africa; G. maritae (Manning & Holthuis),
west Africa; G. paulensis (Chun), south Indian Ocean; and G.
cuinquedens (Smith), northeast Atlantic. Ten new species have been
described from this genus: 4 South American, 2 from St. Helena,
1 northeast Atlantic, 1 Mediterranean, 1 from Madagascar, 1 from
the central Pacific. Members of this genus are large crabs, with
carapace widths ranging from about 7.5 to more than 20 cm.
Characters that are important in the group include: color in
life (red, tan, purple/brown, or white; most species are red or
tan), size of carapace spines in adults, presence of an outer
carpal spine on the cheliped, presence of a distal dorsal spine on
'National Museum of Natural History, Crustacean Division,
the walking legs, relative length of the walking legs, and
structure of the dactylus of the walking legs, whether laterally
compressed or dorsoventrally depressed. Depth range of adults may
also be important.
Some generalizations about geryonid crabs are:
Red species often live in deeper waters than tan ones.
Young crabs of some species may live in considerably deeper
water than adults. The young of G. trispinosus settle up to 1000
meters below the adults and migrate upwards as they mature.
In some species young crabs resemble adults, whereas in others
they may be very different.
Often two or more species occupy the same general geographic
range. When this happens they may be separated by depth range of
Geographic ranges of species tend to be limited. Species do
not occur beyond one part of one ocean, and may even be restricted
to limited areas, such as undersea banks.
ANIMAL-SEDIMENT RELATIONSHIPS INVOLVING
RED CRABS (CHACEON OUINOUEDENS) ON THE SOUTHERN NEW ENGLAND
UPPER CONTINENTAL SLOPE
In August 1987, we began a multi-year research program on the
southern New England upper continental slope (depth: 750 m) using
the submersible DSR/V Johnson-Sea-Link. Our focus was on the role
that large, mobile epifaunal organisms have on the biological and
physical structure of the seafloor. Specifically, we were
interested in examining the red crab (Chaceon quincuedens), one of
the most abundant epifaunal species at the study site. We
postulate the effects of Chaceon on the seafloor are manifold. For
example, redcrab excavation activities are likely to greatly effect
the type and abundance of infaunal species and potentially
interfere with the natural near-seabed hydrodynamic regime.
Alterations in near-bottom velocity profiles can greatly enhance
or reduce larval settlement and subsequent recruitment in soft-
bottom areas, as well as alter the accumulation and/or removal of
organic materials settling on the seafloor. In addition, the
activities of these organisms can greatly alter the physical
structure of the seafloor by destroying or altering sedimentary
texture and fabric, in addition to accelerating rates of sediment
mixing (relative to the surrounding seafloor). Such activities can
greatly alter the movement of particulate and dissolved materials
into and out of the seafloor.
Results of our six-day cruise indicated the study site was
extensively bioturbated by the activities of epifaunal organisms.
Analysis of videotape transects showed that roughly one-half of
the seafloor was covered by a variety of biogenic structures.
2Department of Marine Sciences, University of Connecticut
3Department of Biology, Woods Hole Oceanographic Institution
4Department of GeoSciences, University of Wisconsin-Milwaukee
5Environmental Sciences Program, University of New Haven
Small depressions and pits (-ess than 20 cm in diameter) were the
most abundant structures, while mounds, caves, tunnels, and troughs
were less abundant. Although it appeared that red crabs were the
principal biotic modifiers of the seafloor, other species (e.g.,
galatheid crabs, white hake and flounder) were also acting as
primary sediment excavators or modifiers of the red crab-produced
biogenic structures. Sediment samples collected from several types
of structures indicated significant differences in pore water
content and bulk grain-size analysis; particularly in the upper 2-
4 cm of the sediment. X-radiographs of the sediment indicated
biogenic mixing depths to 20-30 cm, as well as extensive
heterogeneity in micro-topographic relief and sediment textural
Patchiness of biogenic features was quantified over a range
of spatial scales. Three of the eight biogenic structures (small
pits, large depressions and caves) were aggregated at the scale of
a single photograph (3.9 m2). Measures of patchiness as a function
of length scale indicated structure-specific patterns of patchiness
on scales of tens to hundreds of meters.
The most abundant epifaunal organisms at the study site were
red crabs (8.9 organisms/100 m2), followed by eelfish (Aldrovandia
affinis, 6.7/100 m2), galatheid crabs (Munida sp., 2.7/100 m2), Gulf
Stream flounder (Citharichthvs arctifrons, 1.2/100 m2), rat-tail
fishes (Corvyphaenoides carapinus, 1.1/100 m2) and white hake
(Urophvcis tenuis, 0.7/100 m2). Many of these organisms were found
in association with various biogenic structures and their
individual dispersion patterns were, in part, auto-correlated with
patterns of micro-topographic relief.
Samples of infauna revealed the study site was dominated by
polychaetes (65.8% of the total fauna), bivalves (9.8%),
aplacophorans (4.7%), and amphipod crustaceans (3.6%). Infaunal
densities averaged 198.6 per 225 cm2, with a relatively high degree
of between-sample variation. The fauna was dominated by members
of the polychaete families Opheliidae, Paraonidae, Capitellidae and
Infaunal samples collected from various biogenic features
(burrows, tunnels, mounds and pits) were compared to samples
collected from "flat areas" (no structures present). While we are
still processing samples, preliminary results indicated no
discernible relationship between polychaete, molluscan and
crustacean abundance and biogenic features. In addition, no
apparent patterns existed between relative abundance of infaunal
organisms associated with biogenic structures when compared to flat
areas. Infaunal species composition, however, was highly variable
between biogenic structures and areas without structures;
indicating a high degree of spatial heterogeneity in species'
distributions associated with epifaunal-generated disturbance of
Support for shipboard and submersible operations were provided
by NOAA's National Underwater Research Center at The University of
Connecticut (Avery Point). We thank A. Desbonnet, S. Legler-Brown
and R. Petrecca for laboratory assistance.
DISTRIBUTION AND ABUNDANCE OF GOLDEN CRAB, CHACEON FENNERI,
IN THE SOUTH ATLANTIC BIGHT
Elizabeth W. Wenner6
Exploratory trapping for golden crab, Chaceon fenneri was
conducted in 1985 and 1986 off South Carolina and Georgia.
Objectives were to determine depth-related changes in abundance,
size, and sex composition of golden crab in the South Atlantic
Bight; evaluate traps, soak time and gear performance in an effort
to optimize fishing technique; and describe adult life history in
terms of habitat and reproductive biology. A buoyed system with
strings of six traps (three side-entry Fathoms Plus and three top-
entry Florida traps) was fished in seven depth strata: 274-366 m
(150-200 fm), 367-457 m (210-250 fm), 458-549 m (251-300 fm), 550-
640 m (301-350 fm), 641-732 m (351-400 fm), 733-823 m (401-450 fm),
and >823 m (>450 fm). A total of 770 traps collected 4387 golden
crab that weighed 3936 kg.
Catches of golden crab were related to depth. Catch per trap
increased from 2.3 crabs/trap (2 kg/trap) in the shallowest stratum
sampled to a maximum of 12 crabs/trap (10 kg/trap) in the 458-549
m depth zone. Catches then declined to <1 individual/trap in
deeper strata. Catch per trap of golden crab from this study
compares favorably with catch rates reported in the Gulf of Mexico.
Distribution within strata was apparently related to bottom type
since catches were highest on sediments of silt-clay and
globigerina ooze, while few crabs were collected from coral rubble
Sex composition changed with depth with male crabs
significantly outnumbering females in depths from 274-549 m. In
the 733-823 m stratum, female golden crab were significantly more
numerous than males. Over all strata, male golden crab outnumbered
females by 15:1. Although the data suggest segregation of the
sexes by depth, it is not known whether seasonal migrations related
to mating or spawning occur among golden crab.
The small number of females collected precluded any definitive
statements regarding ovarian cycles or spawning patterns. Based
on ovarian development, vulval condition, and presence of seminal
6S.C. Wildlife and Marine Resources Department, Marine
Resources Research Institute
products, it appears that female golden crab reach sexual maturity
at sizes between 90-110 mm carapace width. Ovigerous female C.
fenneri were collected only from May-August; however, these data
do not substantiate a spawning season in the South Atlantic Bight
because we were unable to obtain seasonal coverage of all depth
Submersible dives were made in the vicinity of trap sets to
provide information on habitat types and densities of golden crab.
Observations were made along 85 transects in depths of 389-567 m
approximately 122 km southeast of Charleston, SC. Seven habitat
types were identified during dives: soft-dimpled ooze (293-475 m);
a flat foraminiferan ooze (405-567 m); rippled bottom (419-539 m);
dunes (389-411 m); black pebbles (481-564 m); low rock outcrops
(503-512 m); and coral mounds (503-555 m). A total of 109 golden
crab were sighted within the 583,480 m2 of bottom surveyed.
Twenty-seven percent of the golden crab occurred in the flat ooze
which comprised 31% of the total area surveyed. Density (mean
no./1000 m2) was significantly different among habitats, with
highest values (0.7/1000 m2) noted among low rock outcrops. Lowest
densities were observed in the dune habitat (<0.1/1000 m2), while
densities for other habitats were similar (0.15-0.22/1000 m2). The
low density (1.9 individuals/ha) of golden crab in our study area
and the comparatively high catch per trap suggest that golden crab
are drawn to traps from a wide area.
PATTERNS OF POPULATION STRUCTURE AND ABUNDANCE
FOR GOLDEN AND RED CRABS IN THE
EASTERN GULF OF MEXICO
W.J. Lindberg and F.D. Lockhart7
N.J. Blake and R.B. Erdman8
H.M. Perry and R.S. Waller9
A Chaceon-typical bathymetric pattern of partial sex
segregation (females above males) and crab size inversely related
to depth was corroborated in the eastern Gulf of Mexico for golden
crab, C. fenneri, and seems to hold there for red crab, C.
auinquedens. Variations in that pattern, however, contradicted a
simple up-slope migration with age to fully explain the
distribution. Instead, sampling at medium-to-fine scales and broad
scales helped refine a working model in which females distribute
themselves to accommodate successful reproduction, while males
distribute themselves to compete effectively for mates. Bottom
type, and probably temperature, appear to set limits on
At a medium-to-fine scale, the bathymetric distribution and
abundance of Chaceon spp., between 348 m and 787 m, were sampled
via submersible transects and longline trapping. In addition to
the Chaceon-typical depth pattern, golden crabs were most numerous
at depths where most hard bottom was found (i.e., 550 m in Year 1
and 437 m in Year 2), and were seen disproportionately more often
on hard bottom regardless of depth. Red crabs were found only on
bioturbated West Florida Lime Mud at the deepest contours sampled,
677 m and 787 m. Large C. fenneri males and females were most
numerous at shallowest depths, but large males were also in low
numbers at the deepest contour. Greater proportions of crabs were
mated at the two deepest contours, suggesting that large males,
once paired, carry females down-slope.
Effects of season, geographic area, and depth on broad-scale
patterns of catch per trap and crab size were examined with
replicate trap sampling in the northeastern Gulf of Mexico. Golden
7Department of Fisheries & Aquaculture, University of Florida
8Department of Marine Science, University of South Florida
9Gulf Coast Research Laboratory
and red crabs differed in geographic as well as bathymetric
distributions. Within limits of our sampling, the geographic
distribution of C. fenneri was restricted to the upper continental
slope off peninsular Florida, while that of C. auinauedens was
adjacent to the northern Gulf coast. Neither species was common
adjacent to DeSoto Canyon. Regardless of sex, overall average
catch per trap was greatest for golden crabs at the southeastern
station, while that of red crabs was greatest at the northwestern
station. For both golden and red crabs, the proportion of females
increased counterclockwise around the northeastern Gulf, within
their respective ranges. Male and female red crabs were largest
at northwestern stations. Golden crabs exhibited the Chaceon-
typical bathymetric pattern, but seasonal shifts occurred in
population structure across depths, with some lags between
geographic areas. From these patterns and other data, we suggest
the Loop Current-Florida Current system has a causal relationship
with behaviors affecting distributions of these species.
For golden crabs, in situ density estimates and defined ranges
in the eastern Gulf combine to yield a crude estimate of adult
standing stock at 7.8 million crabs, with biomass estimated at 6.16
million kg (13.6 million lbs). Alone, a sustained major golden crab
fishery in the region does not seem likely. Comparable red crab
estimates are not yet possible.
CHACEON MARITAE STUDIES OFF SOUTH WEST AFRICA
A number of papers dealing with the biology of Chaceon maritae
have been published in recent years, and many of the facts that
have come to light in these papers are relevant to the
understanding of population trends in the fishery. Some of this
information has been combined with new ideas, to explain observed
changes in the annual catch rates and size frequency distributions
of commercial red crab catches off South West Africa/Namibia since
the early 1980's.
Chaceon maritae are slow growing, reaching both maturity and
age at first capture by the commercial fishery at 7-9 years (75-90
mm carapace width (CW)). Ovigerous animals are scarce (comprising
only 0, 1-0, 2% of all females sampled).
Mature C. maritae females move considerably greater distances
than the rest of the population, generally in a northward
direction. It is hypothesized that these animals are migrating
into central or northern Angolan waters prior to becoming
ovigerous. It is further hypothesized that larvae produced may
migrate into surface waters and be transported southwards by the
Anolan Current, to settle in their highest concentrations between
the summer (22 S) and winter (15 S) frontal areas formed by the
confluence of the South Angolan and Benguela currents. Catch rates
have decreased on the Namibian commercial crab grounds since 1980,
but not in a uniform fashion. The northern and central areas of
the grounds are highly dependent on new recruits to the fishery
(i.e. crabs of 75-90 mm CW). Catch rates in these two areas were
reasonably constant up until 1984, but have subsequently eased,
whilst oscillating markedly.
By comparison, the catch on the southern Namibian crab grounds
(south of 20 S) is less dependent on new recruits to the fishery.
Catch rates in this area have fallen drastically since 1980, but
do not show the same fluctuations described for the northern areas.
The oscillations observed in the northern and central areas
are thought to be due to the delayed effects of depletion of the
brood stock by fishing pressure. It is suggested that this
10Sea Fisheries Research Institute, South Africa
situation has led to recruitment now being more dependent on
environmental conditions (e.g. favorable ocean currents for larval
transport) than in the past and that the recent catch rate
oscillations reflect year-classes of variable strengths entering
The decline in catch rates in the southern area is attributed
mainly to the effects of fishing mortality. It is argued that
larval recruitment to this area is minimal because it falls outside
of the area influenced by the Angolan Current.
FECUNDITY AND REPRODUCTIVE OUTPUT IN
CRACEON FENNERI AND C. OUINOUEDENS
Anson B. Hines11
I recently compared the covariation of reproductive traits in
two species of large deep-sea crabs in the family Geryonidae
(Hines, 1988): Chaceon fenneri and C. quinauedens. As in other
crab species (Hines, 1982, in press), body size was the primary
determinant of reproductive output in the two species. However,
their brood masses at 16% and 22% of body weight are considerably
larger than the 10% average in most other species and are near the
upper extreme of apparently typical interspecific variation (Hines,
1982, 1986, in press), but much less than certain commensal species
(Pinnotheridae, Hines, in review; Haplocarcinidae, R.K. Kropp,
personal communication). Egg size in the two species is also
relatively large, and g. auinauedens has one of the largest
reported eggs of brachyurans with marine planktonic larvae. As a
result of partitioning the brood into large eggs, fecundity per
brood is low compared to many species of comparable size.
Comparison of covariation in reproductive traits using ANCOVA to
adjust for differences in body weight showed that C. cuincuedens
had approximately 50% larger volume of the body cavity for
accumulation of yolk, resulting in about 50% larger brood mass than
C. fenneri. Despite its larger brood mass, egg size in C.
auinquedens was about twice as large as in C. fenneri, resulting
in about equal size-specific fecundity per brood in the two
species. The published literature indicates that both species
produce about one brood per year which is incubated over the winter
in the northern hemisphere, although C. auinauedens exhibits low
levels of brooding year-round. Large yolky eggs in C. auinquedens
are likely to contribute to the nutritional flexibility of its
larvae (Sulkin and Van Heukelem, 1980), but apparently have
coevolved with significant changes in female morphology and
The following table summarized relevant parameters for size
and size-dependent variables of reproductive output and fecundity
in the two species. Note that both arithmetic means and least
squares means are given after adjusting with ANCOVA for differences
in body size.
"Smithsonian Environment Research Center
Carapace Width (mm)
Dry Body Weight (g)
Volume of Body Cavity (cm3)
Dry Weight (g)
No. Eggs per Brood
No. Brood per Year
ANNUAL REPRODUCTION IN DEEP-SEA BRACHYURAN CRABS
(CHACEON spp.) FROM THE SOUTHEASTERN UNITED STATES
R.B. Erdman and N.J. Blake12
H.M. Perry and R.S. Waller13
W.J. Lindberg and F.D. Lockhart14
Previous studies of deep-sea reproduction patterns indicate that
in the absence of changing environmental conditions, continuous
cycles are to be expected. Patterns of this type have been
reported for deep-sea Chaceon crabs including C. maritae and C.
auinquedens. However, studies of C. fenneri from southeastern
Florida and the eastern Gulf of Mexico indicate that this species
exhibits a pronounced annual reproduction pattern. Additionally,
C. quinquedens from the Gulf of Mexico also shows an annual
pattern, although more protracted than that of C. fenneri.
Initial studies of C. fenneri were conducted on monthly samples
obtained from the commercial fishery centered off Ft. Lauderdale,
Florida. Oviposition begins in mid-August and continues through
early October with eggs carried for six months until hatching
during February and March. A single batch of eggs is produced
annually, with brood size highly correlated to carapace width.
Samples from this study were limited to depths between 210 and 230
m, thus data on bathymetric distributions were not obtained.
Additional research conducted in the eastern Gulf of Mexico
involved seasonal sampling at five areas over depths of 311, 494
and 677 m, and permitted a comparative study of reproduction of C.
fenneri and C. auinquedens. Chaceon fenneri was present only in
the southern portion of the study area, while C. quinauedens was
collected at all areas sampled. Each species was bathymetrically
segregated with C. cuinquedens found only at 677 m where
temperatures were less than 8.0 C. Female C. fenneri were present
at all depths sampled but were most abundant at 311 and 494 m.
Temperatures at these depths averaged 12.0 and 8.0 C, respectively.
Largest females were found at shallowest depths suggesting a
reproduction related up-slope migration.
12Department of Marine Science, University of South Florida
13Gulf Coast Research Laboratory
14Department of Fisheries & Aquaculture, University of Florida
Both species exhibit an annual reproduction cycle, but
differences in the timing of oviposition were noted. Chaceon
quincuedens carried eggs for nine months following oviposition
during early summer, while eggs of C. fenneri were carried for six
months subsequent to oviposition during late summer. Larvae of
both species hatched during early spring.
The annual reproduction pattern shown by C. fenneri and C.
auincuedens infers the presence of subtle "zeitgebers" which serve
to synchronize oogenesis, vitellogenesis, oviposition and larval
hatching. Variations in reproductive cycles noted may relate to
environmental differences that each species experiences over its
depth range on the continental slope. The upslope movement by C.
fenneri suggests reproductive accommodation to environmental
conditions that may enhance egg development time and reduce
vertical distances for larvae migrating into surface waters. The
molting and reproductive cycle of at least C. fenneri suggests that
although the population as a whole undergoes annual reproduction,
individuals within the population may be reproducing biannually.
REPRODUCTION IN MALE AND FEMALE CHACEON
Gertrude W. Hinsch15
Specimens from the deep waters of the eastern Gulf of Mexico
were collected by commercial fishermen from May 1984 to May 1985
and prepared for study. The carapace width of each specimen
received was measured. The reproductive tracts of the 37 males
and of the 50 females were dissected out and placed in Karnovsky's
glutaraldehyde-paraformaldehye fixative 91965). Tissues were post-
fixed in 1% OsO4, dehydrated in a graded acetone series and
embedded in Spurr's low viscosity media (1969). Tissues for light
microscopy were fixed as above and embedded in Polyscience JB-4
embedding media, sectioned on a JB-4 microtome, mounted on glass
slides and stained with toluidine blue. Tissues fixed as above
were critical-point dried, dehydrated, coated with gold-palladium
and viewed with a Zeiss Novascan scanning microscope.
Mature male Chaceon fenneri are larger than mature females (9.5-
14.5 cm vs 13.5 18 cm). The reproductive tracts are typical of
brachyuran crustaceans. Analysis of light and electron micrographs
suggest that in specimens of C. fenneri from the Gulf of Mexico a
single reproductive season exists.
In the male, the testis and vas deferens is much reduced in size
and contain primarily spermatogonia and sustentacular cells during
the late spring and summer months. Beginning in September -
October numerous acini of the testis become filled with
spermatocytes in various phases of meiosis. As the season
progresses the acini become filled with more advanced stages of
spermatogenesis until they become filled with mature sperm in
January February. While it is possible to see a few acini with
different stages at all times, most of the acini contain more
advanced stages with progression of the season.
The anterior portion of the vas deferens contains some
spermatophores at all times. However, beginning in January it
begins to swell. By March the middle and posterior regions of the
vas deferens become swollen with seminal products as well. The
anterior vas deferens produces the wall of the spermatophores which
then become surrounded with seminal fluids produced in the middle
vas deferens. As the number of spermatophores increases in the
15Department of Biology, University of South Florida
anterior region, some may also be seen in the middle region. The
posterior region of the vas deferens produces an additional seminal
product which is added to the contents of the anterior and middle
regions at the time of copulation. Copulation appears to occur
during March and April after which the reproductive tracts return
to the reduced size seen during late spring and summer.
The spermatophores of Chaceon fenneri contain several sperm.
These are typical brachyuran sperm with several small and long
nuclear arms. The wall of the spermatophore differs from that of
most brachyurans in having two layers. No noticeable difference
can be observed between sperm of C. fenneri and C. quinauedens.
The fully developed ovary of the female is purple in color.
Mature females begin oviposition in September October. They
release their larvae during February March. This suggests an
approximate six month brooding period. Females with developing
broods will have ovaries of various size and color indicating that
vitellogenesis takes place concurrently with embryonic development
of the eggs in the brood pouch.
Other females collected during the late winter spring months
also exhibit ovaries at various stages of development. The seminal
receptacles of mature females appear small in size from May to
February. Swollen seminal receptacles have been found in females
with hatching embryos or egg membranes attached to their pleopods.
Females with ovaries in the early stages of development also appear
to have swollen seminal receptacles at this time. Analysis of the
contents of the swollen receptacles showed quantities of a
translucent material as well as a white aggregate. The translucent
material resembles that of the posterior vas deferens and the white
aggregate contains sperm. In April and thereafter, the translucent
material disappears from the seminal receptacle although the sperm
persist. These sperm are retained until oviposition.
These data suggest that 1) females may mate following the molt
to maturity and that then ovarian development commences and
continues in these females until the time of oviposition or 2)
females are capable of mating in the hardened condition following
larval release. It would seem that females might be reproductive
for several seasons. The number of barnacles attached to, as well
as wear, to the edges of the carapace tend to support this premise.
No eggs or egg cases were found on any females collected during
April or May.
The progressive changes seen in both males and females of
Chaceon fenneri thus suggest but a single breeding season.
AN ASSESSMENT OF THE GEORGIA GOLDEN CRAB FISHERY
Crabs belonging to the genus, Chaceon, are non-swimming upper
continental shelf inhabitants of the world oceans. To date,
approximately 20 species have been identified, and it is likely
that more will be discovered. Species reported off the United
States in the Western Atlantic and Gulf of Mexico include the red
crab, Chaceon quinauedens and the golden crab, Chaceon fenneri
(Manning and Holthius 1984).
Golden crabs are known to range from South Carolina down the
Atlantic Coast of Florida and into the Gulf of Mexico. Although
some information regarding red crab biology and exploitation is
available, data concerning the golden crab is limited. As a
result, the Georgia Sea Grant Program initiated an assessment of
Eight cruises were made between November 1986 through October
1988 aboard the R/V Georgia Bulldog. This vessel is a 22 meter
wood hull shrimp boat which is equipped with a topside mounted
longline reel, and an extensive array of electronics.
Basic longline techniques were used to set out the traps. Fish
carcasses were used for bait. Soak times were generally 20 hours.
Thirty six sets containing 612 traps were made. Yield from 577
recovered traps was 3025 kilograms of whole golden crabs. Average
catch per trap was 7 kilograms. Approximate weight per crab was
0.9 kilograms. The only other animal caught in significant
quantities were jonah crabs, Cancer borealis.
Golden crab sexes are distinct. Males are larger and possess
a narrower shaped ventral apron. Our data also indicate
segregation by sex. A total of 3176 crabs were sexed and measured.
These animals were recovered in depths ranging from 240 to 490
meters, average depth about 366 meters. Eighty (2.5%) of these
animals were female, and the remainder 3096 (97.5%) male.
16Georgia Sea Grant Extension Program
Carapace widths were measured in a similar manner as with blue
crabs, Callinectes sapidus. The size range was 75-195 mm, mean
151 mm, standard deviation 20 mm, and the mode was 160 mm.
Assuming that small crabs and females are not trap shy, and that
crabs recruit to the gear at 75 mm, this data seems to indicate an
old population comprised of multiple year classes. Determination
of the number and age of these classes is difficult, since data
regarding the golden crab are lacking. However, studies on other
species of Chaceon crabs, particularly the red crab suggest that
this is an old slow growing population.
An attempt to determine the population density of golden crabs
in two areas subjected to continuous fishing pressure was made.
A removal method was employed in an effort to accomplish this.
The results of this endeavor showed no significant change in crab
catch over the course of 3 sets. In fact, catch rates and carapace
widths remained almost the same from one set to the next.
There are several possible reasons for this. The most plausible
explanation is that golden crabs are drawn to baited traps from a
considerable distance. Given the desolate nature of this habitat
it may be essential to the crab's survival that it possess the
ability to locate food in remote locations, and move towards it.
In conclusion, the potential for developing a commercial fishery
for golden crabs off the Georgia Coast is minimal. Long distances
to the fishing grounds, uncertain markets for the crab product, and
the hostile nature of working in the Gulf Stream pose obstacles
which may be difficult to overcome.
RESPIRATORY AND CARDIOVASCULAR PHYSIOLOGY OF
CHACEON FENNERI AND C. OUINOUEDENS
IN NORMOXIA AND HYPOXIA
R.P. Henry, H.L. Handley, A. Krarup, and H. Perry17
Individuals of C. fenneri and C. cuinauedens were maintained in
30 gallon aquaria in 35 parts per thousand seawater held between
5 and 10 C. Prior to experiments animals were fitted with
electrodes and catheters and allowed to recover for 24 hours.
Small diameter holes were drilled in the carapace on either side
of the heart and scaphognathite, and copper wire electrodes were
implanted using cyanoacrylate glue and a rubber dam. These were
connected to an impedance converter and oscillographic recorder in
order to monitor heart rate (HR) and the frequency of
scaphognathite beating (Fscaph, ventilatory rate). A catheter was
also implanted in a hole drilled in the branchial chamber; it was
connected to a pressure transducer and recorder in order to measure
branchial chamber pressure (Pbr) during ventilation. Animals were
placed individually in 5 L plexiglas flow-through respiratory
chambers, and oxygen uptake (VO2) was measured as the difference
between incurrent and excurrent 02 concentrations in the water.
Heart rate, ventilatory frequency and pressure were measured
In normoxia (140-150 torr) respiratory and cardiovascular values
were as follows:
V02 HR Fscaph Pbr
umol 02 gm-1 min-1 bts min-i bts min-1 cm H20
C. fenneri 0.0023 + 0.0005 35 + 3 28 + 7 -1.1 + 0.3
C. auinauedens 0.0050 + 0.0008 38 + 1 99 + 9 -1.5 + 0.2
"1Department of Zoology, Auburn University; and Gulf Coast
Ventilatory pauses, characterized by a temporary cessation of
scaphognathite activity and hart beat, which are common among many
crustaceans, were observed for both species, but they were
infrequent. Ventilatory reversals, during which the direction of
water flow through the gill chamber is reversed, were also observed
The water in the chamber was made progressively hypoxic b
bubbling nitrogen through the incurrent channel. As water PO
decreased to about 70 torr, both species maintained near normal
respiratory rates primarily through hyperventilation. Below 70
torr VO2 decreased until a critical low P02 was reached at which
respiration, ventilation, heart rate ceased (25-35 torr for C.
fenneri, and 10 torr or less for C. auinquedens). Recovery of C.
fenneri after the chamber was flushed with normoxic seawater took
approximately 3 hours and was characterized by increased VO2,
hyperventilation, and tachycardia. C. quinquedens recovered much
more quickly (usually by 1 hour), and the changes in VO2, Fscaph,
and HR were much less pronounced during that time.
In a second series of experiments pre- and post-branchial
hemolyph samples (corresponding to venous and arterial samples)
were taken from crabs in normoxia, hypoxia, and recovery, and
hemolymph PO2 was measured. The values for both species are given
Post Branchial PO2 Pre Branchial PO2
C. fenneri (N=5) 88 + 6 32 + 6
C. ruinquedens (N=4) 63 + 16 21 + 10
The arterial-venous difference is maintained in C. fenneri exposed
to hypoxia down to a value of approximately 70 torr; below that it
is reduced to about 2 torr. A similar pattern exists for C.
auinauedens with the exception being that the arterial-venous
difference remains higher (4-13 torr) even under extreme hypoxia.
It also appears that C. fenneri experiences an oxygen debt in
hypoxia, especially at the critical low PO2 at which it ceases
respiratory and cardiovascular activity. Hemolymph lactic acid
concentrations more than double (0.76 mM to 1.5 mM) during hypoxia
and remain elevated (-2 mM) during most of the recovery period.
This does not appear to be the case for C. auinauedens. This
animal maintains respiratory activity to a lower critical PO2,
maintains a higher arterial-venous difference in hemolymph PO2 in
hypoxia, and shows no significant lactic acid buildup in the
hemolymph either during hypoxia or recovery.
In summary, it appears that C. auinauedens is somewhat more
tolerant to hypoxia than is C. fenneri. Both species exhibit
responses to hypoxia that are typical of crustaceans in general,
and which relate more to common body form and morphological
characteristics shared with other species than to any specific
environment. Neither species appears particularly tolerant or well
adapted to hypoxia, but neither do they appear overly sensitive.
Both species are remarkably similar to shallow water species with
regard to respiratory and cardiovascular adaptations.
RAPPORTEUR S COMMENTS
COMMENTARY ON CRAB MANAGEMENT AND THE EAST COAST
UNITED STATES GERYONID FISHERIES
David A. Armstrong18
Crab fisheries comprise some of the richest resources harvested
along the United States coastline. In 1988, total landings
exceeded 455 million pounds worth over 383 million dollars (NMFS,
1989), and equaled about 25% of the total dollar value of all U.S.
invertebrate fisheries. Crabs harvested in the United States
comprise some of the most interesting life history, ecological, and
reproductive characteristics to be found among managed U.S.
species, and yet the nature and extent of management tends to be
relatively similar despite great variation in life history
The geryonid crab conference, convened in January 1989,
considered a variety of life history and ecological data for two
principal species, Chaceon quinauedens and C. fenneri, and
discussed this information in light of the fledgling deep-water
crab fisheries situated in the South Atlantic Bight and
northeastern Gulf of Mexico. In general, participants at the
conference were not overly optimistic about the prospects for large
and sustained fisheries for these species because of their deep-
water distribution, evidence of infrequent recruitment, slow
growth, older age at reproductive and legal size, and fairly low
density over extended regions of the species' range.
As background to analysis of Chaceon biology and life history
characteristics relative to their fishery potential, a brief
overview of other U.S. crab fisheries can serve to highlight
approaches used in management for species that vary considerably
in their life history characteristics. Many points of contrast
and similarity have been reviewed by Jamieson (1986) who divided
crab fisheries into nearshore shallow-water species such as Cancer
and Callinectes, and deep water offshore species such as
Paralithodes and Chionoecetes. In addition to this bathymetric
and on/offshore distinction, it is also informative to distinguish
crab fisheries based on the extent of management which ranges from
fairly passive (e.g. Cancer maqister, Chaceon maritae) to highly
dynamic (e.g. Paralithodes camtschatica and Chionoectes bairdii).
18School of Fisheries, University of Washington
Other U.S. Crab Fisheries
In the temperate to subarctic latitudes of the western U.S.
there are three principal crab fisheries. The Dungeness fishery
ranges from central California to southeast Alaska, and the king
and Tanner crab fisheries largely occur in the Gulf of Alaska and
southeastern Bering Sea (Table 1). The latter two groups, king
and Tanner crab, are extensively and dynamically managed through
joint jurisdiction shared by the state fisheries department and
the National Marine Fisheries Service (NMFS). As in the case of
most crab fisheries, much of the management is directed toward
providing safeguards for reproductive effort by excluding females
from the fisheries and setting minimum sizes to allow for adequate
male reproduction before capture by the fisheries. This tends to
highlight a relatively conservative approach to crab management in
the sense that no spawner-recruit relationships have been
demonstrated for any species of crab in U.S. waters, and this point
was emphasized by several of the participants at the workshop for
Chaceon as well. Noticeably different about the management
approach to king and Tanner crab is the extensive preseason survey
undertaken annually by NMFS that results, eventually, in "harvest
range" guidelines as the basis for a strictly managed quota system
(Otto, 1981, 1986: NPFMC, 1988). Despite prohibition against
capture of females, limited fishing seasons (as short as several
weeks in the case of king crab), and extensive survey estimates
that lead to imposition of quotas, landings for both king and
Tanner crab have fluctuated substantially over the last 15-20 years
(Table 1). The fisheries for these long-lived species (8-10 years
of age for entry in the case of king crab, 6-8 years for Tanner
crab) seem dependent on relatively uncommon, strong year classes,
and year-class strength is otherwise viewed as dependent on a suite
of physical and biological factors that generally lead to poor
survival of larvae or young juveniles (see numerous review articles
in Alaska Sea Grant Symposia for Tanner crab, 1982; king crab, 1985
and Dungeness crab, 1985).
Dungeness crab is fished extensively from California through
British Columbia to southeast Alaska and, over much of its range,
has been characterized by a trend of relatively constant cycles of
high and low abundance (see reviews by Botsford, 1986; Botsford et
al., 1989; Methot, 1989). Management of this species is relatively
passive and carried out by state fisheries agencies throughout its
range. This approach prohibits capture of females, imposes a
minimum size limit of about 165mm carapace width (CW) and enforces
a season closure from fall to early winter (Table 1). No preseason
survey exists to estimate abundance of Dungeness crab, nor is there
Species Sex Size Estimated Season Pre-Season Gear Range of Quota Comment
Fished Limit Minimum Closure Survey Landings
(mm carapace Age in (over last
width) L15 yrs)
shery (lb x 106)
3-130 "harvest range"
Bering Sea guidelines
'Otto 1986; NPFMC 1988
'Otto 1981; NMFS Fisheries stats 1983-88, Alaska Sea Grant 1982
3Alaska Sea Grant 1985; PMFC 1987
Millikin and Williams 1984; Jamieson 1986; Cronin 1987
sEhrhardt and Restrepo 1989
Table L Representative crab fisheries and comparison of major features of management and landings.
age of catch
a quota system. All animals of legal size are vulnerable to the
fishery and indeed many states are highly dependent upon annuaJ
recruitment to the fisheries for the bulk of landings. Despite
threefold fluctuations in apparent abundance (more exaggerated in
certain states such as Washington where landings have gone from
approximately 4 million pounds in 1985 to over 20 million pounds
in 1989), populations are not generally viewed as unstable, and
such fluctuations in abundance are credited to a variety of
physical oceanographic or biological impacts (see review by
Botsford et al., 1989).
The dominant crab fishery on the eastern and Gulf coast of the
United States is that for blue crab (Callinectes sapidus). This
is a fairly complex fishery from a jurisdictional standpoint since
in the area of the Chesapeake Bay, several states manage the
resource and yet have variable management approaches concerning
legal size, season and gear of capture (Table 1). Both males and
females may be captured and, at times, even ovigerous females are
legal in certain states. As a relatively short-lived species (2
years at legal size), C. sapidus has proved to be a useful model
of recruitment variability as explained by physical and biological
features of its habitat (e.g. see review by Sulkin and Epifanio,
1986). A range in landings of about 2.5 fold in Chesapeake Bay has
been explained by variability in larval recruitment due to features
of wind and current transport that affect attendent larval
behavior, and the extent and nature of optimal juvenile habitat
within Chesapeake Bay.
A unique fishery located in the southeastern United States is
that for stone crabs, Menipne mercenaria and M. adina, which is
based not on the whole body of the animal as in other crab
fisheries, but only on the extremely large chelipeds. This
fishery, located primarily in Florida, allows capture of both sexes
and requires a minimal claw size of 70mm propodus length. This
equates to an age of about 2-3 years depending on sex and is
further managed by a closed season designed to essentially protect
female reproduction (Table 1; Ehrhardt and Restrepo, 1989). From
the 1970's, catch increased from about a quarter to 3 million
pounds of claws annually, but has declined somewhat in recent
In the case of these species, relatively extensive literature
exists on aspects of life history, reproductive biology, general
ecology and habitat requirements. Yet despite commercial
importance as fisheries sometimes for many decades a surprising
amount of information is still unknown about patterns of larval
transport, habitat requirements as related to potential year class
strength, and any spawner-recruit relationship between mature
females and any index of juvenile year class success. While not
all such information is needed to manage fisheries, biologists are
nonetheless often hampered in their interpretation of fluctuations
and apparent population abundance because of too little knowledge
of many aspects of species biology; eastern United States species
of the genus Chaceon represent an acute example of this situation.
Geryonid Crab Fisheries
Before reviewing information concerning eastern U.S. species of
Chaceon, it is important to consider biological and fisheries
information from the southwest African fishery exploited by the
Japanese and targeted on C. maritae (Melville-Smith this
proceeding, 1988). This fishery is relatively new, since about
1973, and has been exploited along the southwestern African coast
without benefit of management practices. It is essentially driven
by economic considerations relative to the size of product that can
be economically processed, and the extent of fishing effort deemed
feasible and profitable by Japanese fisheries companies.
Several aspects of the species' life history have important
bearing on trends in the current fishery data. As is the case with
many geryonid crabs, it is a deep-water species distributed from
a couple of hundred to 700m in waters that can range from 4.5 to
10.40C. As a consequence, it is very slow growing and reaches
sexual maturity between 7-9 years of age. Both males and females
are fished and are susceptible to the fishery from age 7-9, but
many may range from 10-16 years of age (Melville-Smith, 1988).
Females are mature at a size of 84mm CW but this size may reflect
fishing pressure since maturity in unexploited populations was
estimated to be about 100mm CW. One dilemma faced by the fishery
is that Japanese pot gear uses a 90mm mesh dimension which is 100%
selective for crab greater than 75mm CW, about 9mm smaller than the
size at sexual maturity (Melville-Smith this proceedings, 1988).
Melville-Smith believes that fisheries over much of the range of
C. maritae have come to rely excessively on prerecruits of a given
year class reaching legal size in a single year. Since the fishery
captures such a large portion of females prior to maturity, and
since a very small fraction of the female population is ovigerous
at any point in time (0.1 to 0.2%; Melville-Smith, 1988) he fears
the combined effects may severely impact egg production and
consequently larval transport to heavily fished areas off the
southwestern African coast. As evidence of this concern, total
Japanese landings have declined from 5.97 million kg in 1983 to
4.72 million in 1986. Based on catch rate CPUE, Melville-Smith
estimated that the density of Chaceon on African fishing grounds
has decreased about 26% over the past six years (Melville-Smith,
Such trends of decreasing abundance and catch rate in the South
African fishery portend negative consequences for the eastern U.S.
fishery for Chaceon as well, with potentially more dramatic
consequences based on relative densities of the two species.
Density of C. maritae has been estimated to range from 40-230
crab/ha based on pot sampling, up to 350/ha based on observations
with underwater photography (Melville-Smith, 1985). However,
density of both C. cuinauedens and C. fenneri, over much of their
range along the eastern U.S. and into the Gulf of Mexico has been
estimated to be substantially less, although little density
information is available. Lindberg (this proceeding) estimated a
standing stock of C. fenneri off Florida's Gulf Coast to be about
7.8 million crab (about 13.6 million pounds). Wenner (this
proceeding) observed densities of only 1.9/ha from submersible
observations of C. fenneri. However, Whitlatch (this proceeding)
reported densities of C. cuinauedens up to 900/ha off the southern
New England coast, and Wigley et al. (1975) estimated densities of
130-380/ha along the shelf of northeastern U.S. Over a distance
of more than 700 km they estimated a standing stock of about 43
million commercial size crab (114mm, 4.5 inches CW) which equated
to about 59 million pounds total weight.
It seems that estimates of abundance of surplus males greater
than 114mm CW suggests the potential for a sustained fishery on C.
quinauedens in the area from Maryland to Georges bank. However,
since the survey by Wigley et al. (1975) there have not been
sufficient studies to indicate whether juvenile recruitment is
consistent on an annual basis, the magnitude of natural mortality
rates (Melville-Smith, 1988, provides estimates for the African
species) and, in turn, estimated survival to legal size. As in the
case of king crab in the Bering Sea, it may be that Chaceon is
typified by relatively infrequent, strong year classes that could
be overly exploited by a directed, open (no harvest quota) fishery.
Fisheries prospects for C. fenneri, the golden crab, in the
South Atlantic Bight to the Gulf of Mexico are more tenuous. The
species seems distributed at very low densities but has the
capacity to locate food and traps over an apparently great distance
(Wenner this proceeding, Wenner et al., 1987) which portends rapid
depletion in areas heavily fished. Given aspects of both species'
life history (reviewed by Hines and others this proceeding) such
as deep water distribution at cold temperatures, slow growth and
relatively advanced age at maturity and legal size, it seems that
high sustained yield is not likely. As in the case of other crab
fisheries listed in Table 1, managers could take a conservative
approach (as apparently has been done) that allows capture only of
males of a size and age beyond reproductive maturity, with the
objective of maintaining species reproductive effort quite apart
from the knowledge of biotic and abiotic factors that affect year
In order to provide some likelihood of reasonable annual catch
by participating fisherman, managers may want to consider a
limited-entry fishery as has been done with a number of Australian
invertebrate species. Given the expense of capitalization for such
deep water fishing, it seems that fishermen are vulnerable to the
vagaries of surplus male abundance which could be quickly reduced
by unrestricted participation. Without an annual preseason survey
and resultant catch quota at the present, there is no basis to
attenuate excessive annual exploitation and spread capture of large
males over several years, particularly if year classes reaching
legal size are infrequently strong as hypothesized for P.
camtschatica in the Bering Sea. Limited entry (and effort) might
achieve this goal of more stable yield, although somewhat blindly
since state fisheries agencies will likely not conduct surveys to
estimate stock abundance as a means to index the degree of annual
exploitation by a limited-entry fishery.
Another option as practiced for some west coast Canadian
invertebrate fisheries that are not well studied and regulated is
that of "boom and bust". So long as rudimentary guidelines
safeguard reproductive effort, the fishery is allowed to grow to
any size (unrestricted vessel participation) and achieve 100%
exploitation as it is able. Eventual decrease in abundance and
reduction in landings are consequences to which fishermen must
adjust as they either stay with Chaceon spp. or move into other
fisheries. Clearly the southwestern African C. maritae fishery is
precarious because management guidelines have not been implemented
to even safeguard reproductive effort through size, sex and season.
In comparison, U.S. Chaceon fisheries can be better managed, but
species recruitment success and population dynamics might be such
as to provide only a limited and marginal fishery off many states.
Commentary on Life History and Ecology of Deep-Sea Crabs
of the Family Geryonidae
Anson H. Hines19
Successful management of fisheries sustaining maximum yield
requires strategic decisions from accurate knowledge of the basic
life history and ecology of target species. In addition,
prediction of the impact of fishing activities on the ecosystem
depends upon knowledge of the fundamental role of the species in
its natural community. For crabs of the family Geryonidae,
development of a data base which will allow informed management
decisions is inherently difficult because of the depth distribution
of the species on the continental slope. Nevertheless, fisheries
are developing for geryonid species, and we need to assess our
knowledge of their basic biology. In addition, as manned and
remotely operated technology has developed, we are increasingly
able to examine the importance of these crabs in the continental
slop ecosystem as a zone of both fundamental and applied interests.
The workshop on geryonid crabs was convened to assess the state
of our knowledge and research progress on primarily two species,
Chaceon auinauedens and C. fenneri (the genus of these two species
was revised in 1989 from Gervon to Chaceon, see below under
Systematics). However, a comparative approach in the workshop
emphasized similarities and contrasts among these two species and
other members of the family, as well as species of commercial and
non-commercial crabs from other families. This readily allowed
both scientists and managers to organize data into meaningful
patterns, to assess the unique and general features of the
particular species, to benefit from the mistakes and successes in
management of other species, and to establish research priorities.
The workshop also emphasized the need for comparative data over the
geographic range of the species, because these contrasts provide
insight into the variability and flexibility of the species'
In addition to assessing the systematic and zoogeographic status
of the family Geryonidae, considerations of life history and
ecology were organized into several subtopics. The topics within
life history analysis fell into the sequence of the crabs' life
19Smithsonian Environmental Research Center
cycle of reproduction, development, growth, and maturation. As
these topics are aspects of population biology, they led logically
into considerations of population stability, dispersal, resource
utilization, and sources of mortality. The workshop also
considered the crabs' potential as regulators of benthic community
structure on the continental slope. The purpose of this commentary
is to summarize the discussion, emphasizing the participants'
consensus about what is and is not known about the basic biology
of the crabs, but it is not meant to provide a comprehensive review
of the geryonid literature.
Systematics and Zoogeography. Initially, very few species were
thought to comprise the Geryonidae; however, in a recent revision
of the family, three genera and 24 species (Gervon with two
species, Chaceon with 21 species including C. fenneri, C.
auinquedens and C. maritae, and Zariquievon with one species) are
now recognized (Manning and Holthius, 1989). The number of
recognized species is likely to increase with additional attention
by systematists, ecologists, and fisheries biologists and with new
technological applications at more sites. Some of the characters
used to distinguish species include phenotypic features, especially
color, which some workshop participants believed were too variable
within species to be reliable diagnostic characters. On the other
hand, the shape (lateral compression vs. dorso-ventral depression)
of the dactyls of the walking legs is apparently both a useful
diagnostic character for some species and a potential indicator of
primary substrate utilization (see Resource Utilization below).
The family is apparently widely distributed throughout the world's
oceans at depths of 200-1200 m, especially on upper continental
slopes. Although some species are small in body size and, through
limited sampling, are known only from very restricted geographic
ranges, the large size, abundance and distribution of some species
indicate that the family plays an important role in the slope
ecosystem on a world-wide basis.
Reproduction. Several recent studies have focused on reproduction
in Chaceon spp. (Melville-Smith, 1987; Wenner et al., 1987; Hinsch,
1988a,b; Erdmann and Blake, 1988; Hines, 1988), following initial
survey work by Haefner (1977) and McElman and Elner (1982).
Gametogenesis is similar to that in other species of crabs.
Chaceon maritae reproduces year-round, and C. auinquedens exhibits
low levels of brooding year-round. However, off New England and
Florida C. quiquedens apparently has a winter peak in brooding, and
C. fenneri is a distinctly seasonal winter brooder off Florida.
Individual females of any of the three studied species probably do
not produce more than one brood per year. Also, some evidence
indicates that individual brood production may be biennial in C.
fenneri (see Maturation and Mating below). Compared to other
species of crabs, egg size in Chaceon spp. is very large, and
fecundity is relatively low (100,000 400,000 eggs per brood) for
such large body size.
Development and Recruitment. Larval descriptions are available
for C. auinquedens (Perkins, 1973), C. tridens (Brattegard and
Sankarankutty, 1967; Ingle, 1979) and C. fenneri (Perry, pers.
comm.). Experiments on C. auinauedens in laboratory culture
indicate that these larvae have long developmental times in cold
waters (125 days at 6-100C) but much shorter times at temperatures
typical of warmer surface waters (only 23 days at 250C) (Rosowski,
1979; Sulkin and Van Heukelem, 1980; Kelly et al., 1982). The
larvae exhibit considerable "nutritional flexibility" in their
ability to develop normally even on relatively poor quality food
such as rotifers (Sulkin and Van Heukelem, 1980), perhaps as a
result of the large amount of yolk invested in the eggs (Hines,
1988). The larval biology of deep-sea crabs is poorly understood
because so few zoeae and megalopae have been sampled in the field
(but see Roff et al., 1984, 1986). However, the lab experiments
and the few larvae collected in the plankton indicate that
development occurs near the surface, as is typical of most crabs.
Laboratory studies of larval responses to temperature, pressure and
gravity indicate that larval C. quinauedens can migrate vertically
through the water column with swimming behavior that allows them
to pass through marked thermoclines, which is adaptive for moving
early stage larvae up to the warmer, food-rich surface waters and
for producing wide larval dispersal in surface currents (Kelly et
Very few small crabs have been collected or observed in the
field; and the timing, habitat, and intensity of recruitment are
poorly understood. The few small crabs which have been found come
from the deepest zones of the species distribution for C.
auinauedens and C. fenneri (Wigley et al., 1975). We need to test
quantitatively the validity of this observation by trying to
determine whether the lack of small crabs observed via submersibles
(Lindberg and Lockhart, 1988) and their paucity from trawls is
typical, or whether our sampling designs have been inadequate. We
need to know whether recruitment is specific to greater depths, or
whether recruitment occurs at all depths and small crabs suffer
higher mortality at shallower depths.
Growth. Deep-sea crabs appear to be slow growing, long-lived
animals. In some cases (e.g., female C. fenneri off the South
Atlantic Bight of North America; Wenner et al., 1987), populations
exhibit polymodal size-frequency distributions; but it is not known
if these modes correspond to year-classes or instars. If the modes
are instars, then the number of instars is not unusually large but
the molt increment is substantial (40-50% for 100 mm crabs
declining to about 14% for 145 mm crabs). If the modes are year-
classes, then these are estimates of annual growth but they tell
us nothing about the number of instars, although the occurrence of
annual molting in females would equate number of post-maturation
instars and years (but see Maturation and Mating below). Most
populations, especially males, show no polymodality in size
structure. Size-frequency analysis of all populations of C.
auinauedens, C. fenneri, and C. maritae do show that males grow
substantially larger (about 50% carapace width) than females.
Other things being equal, large size at settlement will reduce
the time and number of instars required to grow to maturity (Hines,
1986). Size at settlement of the first crab instar is unusually
large (4 mm carapace width in C. quinquedens, Van Heukelem et al.,
1983, and 3 mm in Geryon tridens, Ingle, 1979) compared to most
crab species and is similar to the large first crabs of Ocypode
spp. and Cancer magister (Hines, 1986). This large size at
settlement may be adaptive for otherwise slow growth to adult size.
Growth has been measured directly in C. maritae (Melville-Smith,
1989) and C. auinauedens (Farlow, 1980; Gerrior, 1981; Lux et al.,
1982; Van Heukelem et al., 1983). Farlow (1980) reported molt
increments of 8-21% for captive 73-94 mm female C. cuinquedens,
with .no correlation of increment and premolt size. Limited data
from field tagging studies of C. auinquedens indicate slow growth
and potentially long intervals (perhaps 6-7 yr or more) between
molts of larger crabs (Gerrior, 1981; Lux et al., 1982). In C.
auinquedens reared through the first 5-6 juvenile instars (about
20 mm carapace width) from larvae in the lab, growth rate was
temperature dependent and indicates that 5-6 years would be
required to grow to entry into the fishery at 114 mm or about 7-8
years to maximum size of 140 mm (Van Heukelem et al., 1983). In
the best analysis of growth in a geryonid, Melville-Smith (1989)
used dart tags in epimeral sutures for a mark-recapture study of
C. maritae to determine the molt increment and estimate intermolt
interval in crabs >60 mm. The molt increment percentage declines
with increasing size from about 20-25% at 60 mm to about 15% at 130
mm. Males had larger molt increments than females, and males
exhibited a reduced molt increment after maturity at about 93 mm.
Females molted only rarely after attaining maturity. Estimated
molt intervals for males ranged from about 1.5 yr for 60 mm crabs
to 6-7 yr for 130 mm crabs. By combining the laboratory data for
early instars of C. quinquedens with the field data for C. maritae,
Melville-Smith (1989) estimated the size and age of each instar for
C. maritae, with male maturity occurring at 12 instars, 90 mm, and
9 yrs of age, and maximum growth to 170 mm requiring 16 instars and
33 yrs. Although these estimates for intermolt interval and age
are indeed long, some other cold-water species (Chionoecetes spp.
and Cancer pDaurus) are also estimated to have similar slow growth
and long life. The number of instars and molt increments reported
by Melville-Smith (1989) for C. maritae are typical for most
brachyurans (Hines, unpublished).
Maturation and Mating. Based on growth studies, mature crabs are
5-15 years old or more. Both sexes appear to mature at about the
same size, but males grow larger than females. Maturation occurs
at about 90 mm in C. maritae, 95 mm in C. fenneri, and 85 mm in C.
auincuedens. Although some workshop participants suggested that
females exhibit a terminal molt at maturity but males do not, there
is no real evidence to indicate a true terminal molt (see recent
dispute over this issue for the majid crab Chionoecetes opilio:
Conan and Comeau, 1986; Ennis et al., 1988; Donaldson and Johnson,
1988), though molting may be very infrequent (6-7 yr). In C.
maritae, mature females have been observed to molt, but it appears
that they do so only rarely (Melville-Smith, 1983). Maturation may
occur seasonally in C. fenneri and C. quinquedens, which have
populations with seasonal reproductive cycles; and maturation may
occur all year round in g. maritae, which reproduces year-round.
There are few data to test these proposed seasonal patterns.
Because the two sexes of many populations appear to differ in
their bathymetric distributions (see below under Resource
Utilization), it is not clear how the sexes get together for
mating. A seasonal vertical migration by females has been
postulated (e.g., Wigley et al., 1975), but little hard evidence
is available. Males probably are attracted to mates by pheromones
released by the female, as is the case in many other decapod
crustaceans including many brachyurans; and based on observation
of chemotaxis to bait, the chemotaxis could operate on the scale
of tens of meters in appropriate current regimes (Lindberg, pers.
Observations in the laboratory indicate that mating behavior is
typical of other crabs (Elner et al., 1987 for C. auinquedens; Mori
and Relini, 1982 for C. lonaipes; Wenner et al., 1987 and Perry,
pers. comm. for _. fenneri) but that doubling up and intromission
may last for a long period (11.5 days in C. quinquedens and weeks
or more in C. fenneri in the laboratory). Males apparently may
mate with intermolt females as well as copulating with newly molted
females. With post-copflatory marking analogous to those on
Dungeness crabs (Cancer magister) and snow crabs (Chionoecetes
opilio), female Chaceon maritae show abrasions on their walking
legs from mating embraces, as well as darkened vulvae and abrasions
from contact with male pleopods on the ventral carapace under the
abdominal flap (Melville-Smith, 1987). While categorization of
female vulvae does indicate maturation and mating in other Chaceon
spp. (e.g., Wenner et al,, 1987), similar mating marks have not
been recorded for female carapaces of other geryonids.
In C. fenneri there is controversy over whether females molt
and mate annually (Hinsch, 1988a,b) or molt after a brood is
released and mate later to produce the next brood in alternate
years for a biennial reproductive cycle (Erdman and Blake, 1988;
Erdman, in review). Precedent occurs for such a biennial cycle in
cold-water for the blue king crab Parlithodes platvyus (Jensen and
Armstrong, 1989). Obviously, reproduction could occur within the
population each year; but with only half of the females producing
a brood, the population's egg production would be only half of that
if all females brooded annually. As in some other groups of crabs,
females may store sperm for prolonged periods, producing one or
more broods without additional copulation. However, there are few
data to test this, and no one knows if sperm can be stored by a
female from one instar to another. Some of these reproductive
strategies may be highly adaptive for cold, food-poor waters of the
deep sea, where energy for yolk accumulation may be difficult to
acquire; and they may also serve to ensure reproductive success
when mates are difficult to find.
The length of reproductive life in geryonids is not known, but
life spans of up to 33 years have been speculated. No evidence of
senility has been found, put most population samples provide too
few females to yield adequate analysis of reproductive activity by
size (age). Mature males appear to be equally reproductive at all
Population Stability and Dispersal. Although population densities,
sexual composition, and size structure appear to vary significantly
in space for C. fenneri, V. auinauedens, and C. maritae, we have
very little real data n annual or long-term variation in
population abundance. Because of the potential for long-distance
larval dispersal, there is concern that recruitment for key fishery
locations may depend heavily on reproductive stock under distant
management jurisdictions.i For example, recruitment for the C.
maritae fishery off southwest African waters appears to be derived
from stocks to the north. Similarly, Kelly et al. (1982) proposed
that larval C. auinauedens are transported to the mid-Atlantic
Bight by the Gulf Stream. Although recruitment is poorly understood
in any geryonid species, failure to find many small juveniles and
comparisons with recruitment fluctuations in blue crab (Callinectes
sapidus), Dungeness crab cancerr maaister), snow crab (Chionoecetes
opilio), and king crab (Paralithodes spp.) populations suggest that
major successful recruitment events occur very rarely; but those
recruits may dominate a population for a long period, perhaps 10
years or more.
Movement of some geryonids appears to be substantial and could
cause significant dispersal. Despite apparently intensive trapping
in some locations (e.g., the C. fenneri fishery off Ft. Lauderdale,
Florida), there has been no apparent reduction in crab abundance,
suggesting that other crabs are "filling in" from some unknown
distance in the surrounding waters. Melville-Smith (1987) reports
significant movement of Q. maritae in mark/recapture studies off
the coast of southwest Africa/Namibia, with differences between
sexes. Mature females exhibited significant net movement northward
and greater movement than other categories of crabs. Large males
moved farther than small males. Over 32% of the recaptured crabs
moved greater than 100 km over a period of years of the study. The
net rate of movement wasi only about 0.05 km/day for males and
immature females, while mature females moved 0.11 km/day southward
compared to 0.46 km/day northward. These movement data may
indicate a sexual pattern of migration off the African coast. Lux
et al. (1982) found that iost net movement was under 20 km for C.
auinauedens off southern New England, although some individuals
moved as far as 90 km during a 7 year study period. No evidence
of seasonal migration was found, and most movement appeared to be
up and down the continental slope rather than long-shore.
Stock identification is poorly understood for geryonid
fisheries. Because of the potential for wide larval dispersal and
substantial benthic movement of juveniles and adults, there is
little understanding of any barriers that would serve to delineate
biologically appropriate management boundaries or to provide clues
about deme size and gene 1low. Population size of C. maritae off
southwest Africa has been estimated by photography and tagging to
be 21.6 and 19.5 million crabs respectively, while trawling
underestimates population size at 1.9 million crabs (summarized in
Melville-Smith, 1988). Since early population estimates for other
fisheries are largely based on trawl or trap data, little trust can
be placed on those reports. More recent surveys from submersibles
(Whitlatch, unpublished; Lindberg and Lockhart, 1988; Wenner and
Barans, in press) give more accurate information for C. auinauedens
and C. fenneri, but the geographic extent of those surveys is
limited, making it inadvisable to extrapolate population size.
Resource Utilization (depth, substrate, food). Geryonids show
habitat partitioning by depth and substrate. The majority of
available data is for bathymetric distribution. Chaceon fenneri
and C. auinauedens occur at different depth zones in the eastern
Gulf of Mexico, with C. fenneri distributed shallower than C.
auinauedens (Lindberg and Lockhart, 1988; Lindberg et al., 1989).
In addition to interspecific zonation, most populations show
intraspecific zonation with the two sexes distributed differently.
For C. fenneri, C. auinauedens and C. maritae, females tend to be
more abundant at shallower depths (Lindberg et al., 1989; Haefner,
1978; Melville-Smith, 19817), although the few females trapped by
Wenner et al. (1987) in the South Atlantic Bight were deeper than
Chaceon maritae. C. luinauedens, and C. fenneri are found
patchily distributed on both soft and hard substrates. Chaceon
auincuedens appears to be most common on soft substrates, while C.
fenneri apparently reaches highest densities on hard substrates
(Wenner and Barans, in press; Lindberg, pers. comm.). The
laterally compressed dactyls of C. fenneri may be better adapted
for hard substrates, while the dorso-ventrallly depressed dactyls
of C. auinauedens may allow easier movement over soft substrates
(Manning, pers. comm.). The association of these crabs with
particular substrates is of particular interest to fishermen, who
want to fish high density patches of crabs but must avoid hard
substrates which might foul gear.
The diet of geryonids is poorly known. They are often
categorized as scavengers that feed opportunistically on bonanzas
of carrion deposited on the bottom from overlying waters. The only
significant published analysis of stomach contents of crabs not
captured in baited traps is by Farlow (1980) for C. auinauedens off
southern New England, where the crabs are predators as well as
scavengers. Small crabs fed mainly on sponges, hydroides,
gastropods, schaphopods, small polychaetes, and small crustaceans;
large crabs also took larger prey (including fishes, squid, and
Hvalinecia) but it is not entirely clear if these items were
scavenged or captured alive. Diel changes in gut fullness of crabs
in the field indicate 1-2 peaks of feeding during daylight hours.
Crabs about 250 g in weight consume 0.09-0.7 g dry weight of food
per day, with much of the food mass as mucus and sediment that may
be of little nutritional value. Observations of feeding behavior
from submersibles indicates that C. auinauedens may be a deposit
feeder to some extent, and that C. fenneri is attracted from
considerable distances (tens of meters) by olfactory cues from
Sources of Mortality. Few data are available on sources of
mortality for geryonids. Several species of fish are reported to
prey upon juveniles (Melville-Smith, pers. comm. for C. maritae),
but there are few published records of geryonids in fish stomach
contents (Sedberry and Musick, 1978 for the gadid Phycis chesteri
on C. quincuedens). Mortality rates from fishing have been
estimated at 0.24 males and 0.41 females per year (Melville-Smith,
1988). Other estimates of mortality are lacking.
Community Interactions: Deep-Sea crabs as Predators, Bioturbators,
Competitors, and Hosts. Geryonids may have a significant role as
a dominant predator in continental slope communities. Analysis of
stomach contents for C. quinquedens indicates active predation on
a wide variety of infaunal and epibenthic invertebrates (Farlow,
1980). Observations of C. quinquedens off southern New England
(Grassle et al., 1975; "aedrich et al., 1975; Whitlatch, pers.
comm.) and C. fenneri (Wenner, pers. comm.) off South Carolina
indicate that these crabs are major sources of bioturbation in the
surface sediments of the slope. Locomotion and active digging in
addition to feeding activities appear to disturb and turn over the
sediment extensively in areas where the crabs are relatively
Competition among geryonid crabs is poorly understood.
Bathymetric partitioning by C. fenneri and C. quinauedens could
result from competitive interactions between these two species in
which golden crabs exclude red crabs from shallower depths.
However, C. quinauedens does not move shallower in areas where C.
fenneri is absent in the: Gulf of Mexico (Lindberg et al., 1989).
Off New England, Cancer, borealis and Homarus americanus may be
competing with C. quilhuedens at the shallow edge of its
distribution. Although Oeryonids are not obviously aggressive in
captivity, field observations of crabs approaching traps do show
agonistic interactions with threat displays typical of other
brachyurans (Lindberg, pers. comm.). Competition for mates is not
known, but prolonged mating may serve to prevent multiple males
from copulating with a female.
A variety of commensal species occur on geryonids, including
stalked barnacles (Poec lasma spp.) and a polychaete Dorveillia
ceronicola on C. fenneri and C. quinquedens. Although the density
and size of barnacles fooling a crab's carapace may be indicators
of time since molting, too little is known about the biology of the
barnacles to calibrate their rates of settlement and growth.
Chaceon quinquedens and C. fenneri also have a high frequency of
chitinolytic bacteria, which cause dark lesions on their carapaces.
The frequency of lesions may also be an indicator of time since
molting, but little is known about the time course of their
development nor of their potential pathology.
EDITED GROUP DISCUSSION TRANSCRIPTS
U. LINDBERG: We would Like to hear comments about what you heard yesterday and, based on your experience,
what you think the particular needs of the fishery are. Dick, do you want to lead off?
D. NIELSON: I'm Dick Nielson, commercial fisherman in Fort Lauderdale, Florida. First of all, I'd Like
to thank the people who set up this workshop. I think it's very interesting to me as a commercial fisherman,
and I'm very proud to be here. You have done a tremendous job bringing these people from all over the world
to this workshop. I particularly Love workshops, more so because every time we go before regulatory powers here
in the State of Florida we normally have about three minutes to speak, and I've been given a lot more time than
that today and I appreciate that, believe me.
Commercial fishermen here in Florida are certainly under a lot of pressure. I wrote down quite a bit of
information here, but I've got it titled "Golden Crab Trapping" and it really should be "Last Frontier of
Commercial Fishing in Florida." I Look at the deep-water golden crab as a Last frontier, and I'm very
interested in harvesting it commercially.
It all started about three years ago. Howard Rau, a commercial fisherman who traps for Lobster and fish,
moved out to deeper waters off Fort Laudercatle in search of fish. In 700 feet of water he began to catch golden
crab in his fish traps. Howard Rau was the first fisherman to Land golden crab in the Fort Lauderdale area.
When I received news that we had golden crab off our east coast, and tasted some crab from Howard which was
excellent, I decided to design and build a trap that would catch them more efficiently. This was done through
research and trap design Literature from Alaska, Canada and the University of Rhode Island.
The trap had three-eighth inch rebar frame and five-inch nylon webbing mesh on the sides and top with a
one and a half by one and a half plastic coated wire on the bottom. The trap had a double funnel entrance five
inches high, 24 inches wide. The trap site is four feet by six feet by 30 inches high. Five traps 900 feet
apart make up a trawl. Because of the Gutf Stream conditions, traps were retrieved by grappling.
A five-inch escape ring was installed at a later date to release females and smatter mates on the bottom.
Research on golden crab reproduction and spawning was done aboard my vessel. I highly recommend a working
relationship between fishermen and biologists. When the time comes to regulate the golden crab, I want to help
determine those regulations.
Three of us fishermen at this meeting have a proposal of regulations that we would like to see in place
on the golden crab before we even really get into harvesting this crab on a Larger scale. One of the first
proposals would be an escape ring sized to release females and small mates. I would like the scientists to tell
us the most appropriate size. Secondly, we recommend no harvest of female crabs. We have never harvested
female crabs. The female is a smaller crab, about half the size of the adult male, and we don't catch that
many of them. We think it's much better just to Leave that female crab on the bottom and help to preserve this
resource. The third proposal would be a carapace measure for the male crab that would translate to about a
pound and a quarter male crab. We would like to release anything below a pound and a quarter, also targeted
by the escape ring. Once again, I Leave the width of that carapace measure to be determined from scientific
research that has been done. We can get together with you people and come up with some figures on that.
I certainly have enjoyed this two day workshop. It has been a pleasure being here and I certainly
encourage more research. Any time the commercial fishermen of Fort Lauderdale can help in providing a vehicle
for this research, we are more than happy to accommodate you. Thank you very much.
U. LIND8ERG: Thank you, Richard.
D. ARMSTRONG: What is the approximate size, in inches, of an animal that weighs one and a quarter pounds?
R. ERDNAN: About 125 to 130 millimeters.
G. HINSCH: If you took at the size rage at which they seem to be reproductively mature, the smaller sizes
for mates coincide with the upper size classes of the females. About 130 millimeters and larger are mature
males while 130 mm to about 85 nm are mature females. So if you exclude the tower size classes of mature males
you would automatically exclude females.
D. ARNSTRONG: This fishery has been under way for three years in Fort LauderdaLe?
D. NIELSEN: Yes, but in a very dormant state. We primarily earn our living with fish traps and Lobster
here. The vessels we have are too small for large-scale crabbing. Howard Rau already has a Larger vessel and
is gearing up for the golden crab, as well as fish trapping and lobster fishing. I am working on a new vessel
now. It has been a long slow process gearing up for these fisheries. We have done the ground work, we have
used the technique of grappling these traps and catching the crabs, and we have that behind us. Ue haven't
really supplied crabs to market consistently, and the market looks good to me. We've shipped crabs all over
the world; we've shipped crabs all over the country and it's been widely accepted, only we couldn't meet the
demand. We have been pretty well stable an.now that we're about to move out and start greater harvesting, we
want to go to the federal councils and get some regulations in place before this industry takes off.
D. ARMSTRONG: Presently are there any state regulations at all?
D. NIELSON: Not to my knowledge. I don't know of any.
D. ARMSTRONG: Witl the State automatically come in immediately or at some point when they sense the
industry is expanding?
D. NIELSEN: When you fish federal waters the State of Florida has no jurisdiction. We work very closely
with the federal councils. We are regulated with fish traps and Lobster gear in federal waters, and we have
a good relationship with the federal council s. I don't see any problem with going before them as fishermen and
proposing these regulations, to get them ir place so we can protect this resource and have it for a good many
years down the road.
R. ERDNAN: The only thing that the State does presently is to code the species as part of the State's
statistical analysis. The State presentlylrecords only gross pounds landed.
N. BLAKE: The State of Florida has been reluctant and will continue to be reluctant to either do any
research or to participate in any regulati ns that involve a fishery in federal waters even through the catch
from that area is probably totally Landed in state waters. They just will not participate in any of the shell
fisheries that involve federal waters.
D. ARMSTRONG: And that simply means beyond three mile limits?
N. BLAKE: Well, no, it varies (nine miles in the Gulf).
D. ARMSTRONG: It's surprising in a sense because most Landings of dungeness crabs, for instance, are
beyond three mile limits but states have jurisdiction. In fact, the federal government has abdicated authority
in those instances and only retains it in partnership with, say, a state Like ALaska in the case of Snow crab
and King crab fisheries. It surprises me the State could never come to have their specific regulations and
standards and enforce them.
F. LAULER: This fishery was started after the Iagnuson Act went into effect. The fisheries on the west
coast were going long before that. I think that's one of the reasons why the western states retain jurisdiction
and Florida doesn't in this particular fishery.
D. ARMSTRONG: Also in some cases with relatively Little fisheries value, the federal government cannot
afford commitment of funds to persistent monitoring and management of them, so it falls to the states to do so.
N. RAl: I think it's safe to say that we would oppose the golden crab being put under the jurisdiction
of the state of FLorida.
G. ULRICH: If you fish an area for a while do you notice a decline in the catch?
D. NIELSEN: We were very limited by the size of the vessel, 36 foot, and the hydraulics. The depth of
the water Limited us to working a certain area and we stayed in that area at that same depth. We yielded about
100 pounds per trap per week for two years. We weren't able to expand out deeper or move around Like we
normally would because of the vessel, so I can't give you a real answer to that question.
R. NIELSON: I wanted to add just a couple of things. To achieve that 100 pound average for over a year
and a half, we were fishing from approximately 118 fathom to 125 fathom in the same basic area. There has been
some talk about how much pressure the resource can stand, and either those crabs were six feet deep when we
started or they were being drawn from a wider area than originally thought. These crabs could be moving miles
to get to these traps because it's amazing the amount of crabs we took out of this one area. We would still
be doing that today except another fisherman came and set more traps in the area right outside of where we were
fishing, and since then I have moved to a different area. The catch has not been up to a 100 pound average,
but there are days that we average 50, 60 pounds of crab which is acceptable to us.
Let's talk a little bit about marketing. when we first started marketing this crab we ran into all kinds
of problems. Originally, we sold the crab whole. People took it home and boiled it for an hour and a half
trying to get it to turn red, then would come back and complain. We got into the retail market where we sold
fish and crabs. We talked with the owner to basically inform the people and had some brochures made up that
explained how to cook the crab. We found that even when people cooked golden crab for 18 to 20 minutes and then
pulled the carapace off, they had a mess on the top of their table and that turned people off. So we decided
as a marketing gimmick to clean them free which would help the retail markets. When people buy these crabs in
a retail market they pay for the whole crab, and the retail market splits it and cleans it so the people take
home only what they eat. It's much easier for them, no muss no fuss.
Once people try this, they call the fish market every day. we can't even catch enough crabs to keep one
retail market steadily in crabs. I brought in 500 pounds of crabs on Wednesday and they are probably gone this
I think down the road that you're going to find its the live market that is going to last. We've had large
boats from Alaska and Massachusetts come doYn and try to process and freeze the crabs on the boat, and they have
all gone out of business. I think you'll aee the only market that's going to Last is for live crab. You can
pack these crabs in styrofoam boxes, put a couple of ice packs on the bottom and couple on top, and ship them
to Massachusetts, or to Spain. The crabs will get there with approximately a ten percent mortality rate, which
is pretty decent. A Lot of people won't eat a blue crab if it's dead. When a golden crab is dead you can
butcher it and cook it, and it's perfectly fine. As for the shelf life, once a cluster is cooked, you can keep
that crab in your refrigerator for five or six days and it's still perfectly good. It holds the flavor and
doesn't spoil. You have to cook the cluster. If you don't cook the cluster, black spot occurs in a matter of
hours, so once a crab is cleaned it has to be cooked.
One of the things I'm interested in, and that would interest you people, are the small crabs. From the
reports we had yesterday no one knows where the juvenile golden crabs are. I would like to find that out. Just
where do they go, are they way down deep and then migrate in shore as they get sexually mature?
I would like to say once again that if you are down in the Fort Lauderdale area and you would like to go
out and see how we fish for crab, you are more than welcome to come out for a day. If you are planning studies,
our boat is always open to anyone who wants to do the work to help the resource. I thank you for inviting us.
D. ARmSTRONG: I'm curious, what is the crab worth per pound either off the vessel or retail?
R. NIELSON: We get a dollar a pound off the boat, retail is anywhere from $1.49 to $1.69 a pound. We
started out trying to get $1.50 off the boa, and they were selling it for $3.59 a pound retail. We had to cut
way back. We were down to 75 cents, and the retail markets were selling them for 99 cents just to get it
established. Once we got it established wd raised the price up a little bit so we could make a decent buck at
A. HIKES: That's for whole crabs?
R. NIELSON: Yes, that's the whole crab.
BLAKE: You've got to remember they are fishing some six to ten miles offshore, you couldn't sell it
on the west coast of Florida at a dollar a pound because the fishery is 100 to 150 miles offshore and you need
a much bigger boat. Your investment would be much greater almost any place besides the Fort Lauderdale
R. NIELSOE : We have it easy in some respects, by fishing only five to ten miles off the coast. But it's
not the easiest thing in the world to fish in a two to four knot current, especially using the grapple to hook
R. MILLER: How Large an area did you fish over the two years before you moved your gear, how many square
miles of bottom?
R. NIELSON: I would say approximately six square miles.
R. NILLER: How many pounds did you take out of that area?
R. NIELSEN: I don't have an exact figure, but roughly an average of a thousand pounds per week for over
a year and a half. Seventy-five thousand pounds would be a rough figure.
D. ARMSTRONG: Have you lost gear using the method of grappling?
R. NIELSON: No. When we first started we would go out there and grapple for six hours and not even touch
a trap. Once you get used to it and get the technique down, you Let the current work with you instead of
against you. I've Lost one trap to the bottom in three years.
D. ARMSTRONG: Do you have any feeling whether the traps would continue to fish through extended periods
of time without bait, that is just by virtue of habitat itself?
R. NIELSON: We have stainless steel gates that hang down to allow the crab in but are not supposed to
allow the crab out. Once the bait goes, these crabs will find their way out of the trap. Similar to the fish
traps, we use what's called a wire tie which is a small diameter wire that construction companies use to tie
rebar together. We use it on the golden drab traps in case the traps are Lost, so eventually the door will
G. HINSCH: Do you get any of the giant isopods when you fish for golden crabs?
R. NIELSEN: No.
G. HINSCH: That's a by-catch in the Gulf of Mexico fishery.
R. NIELSON: I've seen them from the Keys, but I've never caught one. One fisherman in the area has caught
G. HINSCI: They are quite common out here.
R. NIELSON: We don't see them, probably because we're not fishing deep enough. I imagine if we get out
farther we'll run into them.
F. LAULOR: What other kinds of by-catch do you get?
R. NIELSON: Very little, we get a Cacer crab once in a while. On a big day you might have 20 pounds.
There is a spider crab, Rochinia, that seea to be more on the upper depth Limits where we fish. If the gear
is moved to the inside Limit of the golden crabs you'LL get five to six of them in each trap. I caught maybe
ten fish in three years, blackbellied rose fish and a Snowy grouper. Howard Rau caught a Spiny dog fish,
another guy caught a Goose fish, and we caught one American lobster.
G. HINSCH: Did you ever find any shovel-nose Lobsters?
R. NIELSON: No. We do catch them shallower in our fish traps, but we don't catch any out there.
U. LIIDBERG: Sean or Howard, do you have any words of wisdom you care to pass along to us?
S. INGRAM: My name is Sean Ingham. I'm a commercial fisherman from Bermuda, and I would Like to thank
all of those who have been instrumental in inviting me to this workshop. I have Learned quite a bit and it's
generated quite of bit of food for thought regarding the future in Bermuda. I'm going to go back with this
information, sit down with the authorities and see if we can come up with some answers and try to develop a
fishery for golden crab in Bermuda.
At the moment I'm the only person working it in a very small way with just a few pots. I had to go south
to Belize to set up a fishing operation, and while there we attempted to find golden crab but didn't. Instead
we got a tot of Bathynomus isopods. We got our fishing operation going there and came back to Bermuda where
I've only been back into fishing for about a year. This year I'm optimistic. I'm getting back into it, and
we're in the infancy stage. No real markets are established in Bermuda, so I have to both catch and develop
markets. Only a few restaurants use golden crab.
When we started back in 1984 with golden crab; we sold the crab Live at $2.50 a pound, and the restaurants
were able to make money. I think now that we can still maintain those prices even with inflation. As I said,
we have to do everything ourselves right from square one. We have had promises from the Bermuda government to
help us. Any questions?
M. BLAKE: What kind of catch rates do you experience?
S. INGRAM: Well, fishermen loathe change, particularly in Bermuda. They did not want to venture into new
types of traps which you are familiar with, even with the documentation I got from Ray inning and Warren
Rathjen. We needed a trap that could be Utilized both for fish and crabs, depending on the time of year, the
circumstances, and markets. I was working an eight foot by eight foot, four-foot-six high trap, which was set
around July 1st in 1984. We went back on July 4th, and we didn't know what we were going to catch, since none
of the authorities could tell us what was out there. They told me I was wasting my time, there was nothing out
there, and to forget about it. So these crabs came up on July 4th and jokingly we called it the Independence
crab, because it was going to make all the fishermen independent.
Later on as we moved these traps into the areas between the banks and Bermuda's edge where the strong
currents were, we had one trap that cane up virtually packed, and we couldn't get it aboard the boat.
EventuaLLy, it just gradually broke up against the side of the boat. So then we started fishing smaller traps
that we could manage better, and we found as we went down in size, the trap caught Less. But we were averaging
30 pounds a trap, sometimes less, sometimes more. With smaller traps the crabs either got out or we didn't have
much success. The shallowest depth we found the crab was in 420 fathoms, nothing shallower than that. We have
tried up and down the slope and haven't found any.
E. ENNlER: Have you found the sex ratios to be roughly equivalent off Bermuda? I know that Brian
Luckhurst reported that, and I was wondering from your experiences whether you found a fairly equal number of
males and females?
S. INGHAN: Most of that information Brian Luckhurst has. I have had enough to try and catch it and market
it. We used to chill the catch down to about 26, 27 degrees Fahrenheit, and this narcotized the crabs, and
stopped them from attacking each other. IWen we got in, that catch was weighed, and Loran fixes were available
for Brian's information. He would have alL that information.
D. NIELSON: What depth of water were you fishing?
S. INGRAN: 420 fathoms. We found the species of crab at that depth was the biggest. As we went deeper
the crabs got smaller, and then a smaller'species started. We went out as far as 1,900 fathoms. This year
we're intending to go down to 2,800 fathoms relatively close to Bermuda on a one shot deal, because I'm now in
the financial position to spend all my time researching. I was relatively close to shore working in a mile of
D. NIELSON: What size are these crabs, the largest male, four pounds, three pounds, can you give me a per
S. INGHAN: Ue caught some very big crabs in the five to six pound range, and on one crab the carapace was
about 20 inches across. Mind you, the funnels in the traps are large. I've seen the Nielson trap, and your
funnels are not that big. I would say if you tried bigger funnels in a Larger trap you may find a larger crab.
With what you've done now, you're limited in the size crab you can catch, and that's not necessarily the
biggest. The biggest one was weighed by Luckhurst at 16 pounds one ounce.
R. WALLER: Are we dealing with the same crab here?
S. INGRAM: There has been very little help from the government to determine that.
F. LAULOR: Were you taking both males and females?
S. INGRAM: That's true. At the present moment we are still taking both sexes. No laws govern the crab
in Bermuda. Similar to the FDA laws that you have in the United States, we will follow your example. Whatever
Laws you enact up here, we'll probably follow suit down there.
When the crabs came up, both the scientists and fishermen Looked on it as a waste of time to throw the
females and smaller crabs back because they were going to die. We didn't realize what a strong constitution
these crabs have. We have found that out from the seminar here. Where machinery and refrigeration has failed,
crabs have been held up to 50, 60 degrees and live. I think they have a chance if we can work out what size
crab we're going to release. The mesh size we were working with was two-inch by two-inch mesh.
F. LAMLOR: Is that the size you use on the fish traps?
S. IGRIAM: Same size on the fish traps. We are a heavily regulated fishing industry in Bermuda. Back
four or five years ago, I had 100 legal traps. Prior to that it was 400, and they have cut me from 100 back
to 50, and from 50 I've been cut back now to 34. This year we're being cut back to 26.
I have tried to find an alternative way of fishing in Bermuda for the fishermen, and have tried to get away
from more traditional types of fishing because of complaints about overfishing, the targeting of small
herbivores for filet, and the limited space and platform that we have to work on. I'm trying to find an
alternative that the fishermen can get into and continue, but we need to regulate that right from the beginning
rather than at the end and try to bring it back, which always has been a big problem.
R. MILLER: Conventional wisdom is that animals that deep are probably quite old and quite slow growing,
so your fishing operation could be viewed as a mining operation rather than a sustained yield. Some other
people have more experience with these de4p water habitats, but I think that would be a safe generalization.
You'll fish an area out once and the next time it will be your children who will fish it again. We won't have
a sustained fishery at great depths for any commercial species.
N. BLAKE: It hasn't been brought up yet, but if we're talking management, sometime along the line in this
fishery we should be talking limited entry, whether it be in Bermuda, in the States, or wherever. I don't know
how the Nielson's feel about that but if 500 people see a resource out there, especially in a deep water species
where it could be fished out quickly, limited entry may be the only answer.
S. INGRAM: As for limited entry, in Bermuda the fishermen have worked single traps. We attempted to use
traps on strings and it didn't work out too well. We set traps about 500 feet apart but they tended to get
snared up in the rocks. Now we have the knowledge, we've seen enough films and fishermen working.
Just a point of interest, doors on our traps, as part of the law in Bermuda, are tied with biodegradable
rope by law. We also found that a conventional fish trap that's set in five or six fathoms, will last
approximately three years. You go out to $0 fathoms, you get about two years from a trap. You take that trap
down off the edge and go out for crab and you get about three months because the wire starts to erode very
quickly, either from electrolysis or what, I don't know. The sisal rope in shallower waters is discolored after
about six weeks. In 500 fathoms, that size of, rope looks perfect six weeks later, but two weeks later that rope
is perfect to look at, looks brand new, but falls apart. It's very interesting and I don't know why it happens.
We were catching most of the crab up into the north and northwest, and the bait in the trap was in
excellent condition sometimes a week after. On the southern side of Bermuda, we found that the bait after just
one day looked Like it had been cooked. I thought it was being attacked by some type of bacteria but some
scientists suggested it could have been hot vents.
U. LINDBERG: Why don't we shift gears and turn the floor over to our rapporteurs to try to integrate the
biology from yesterday with some of the fisheries comments from this morning.
R. SMITH: For Chaceon maritae, I would argue that it doesn't have a terminal molt. I propose that molt
plus one other, in other words two mature molts. I think you know there are several reasons for that. For
starters I have kept mature animals in tanks, and they have molted to soft shell, I am quite convinced that they
are not terminal molters. Then related to the up and down movement pattern, I've done a lot of tagging, and
I've got to look at it from a seasonal point of view. It tends to suggest a seasonal movement up and down, but
by size. In other words, as soon as they got a little bit bigger they tended to repeat the tag returns from
a shallower depth interval; as they were getting Larger they moved up shelf.
A. HINES: Would that be just by default? If Little ones are only found deeper, as they grow they disperse
from that zone, and then you would tend to get them at shallower depths, or do you think it's really a
R. SMITH: I'm not quite sure, but what I would say is that generally the slope is of a distance that they
could easily move five, ten miles up slope and get to whatever depth they would Like, so it seems that they
could easily move that distance if they wanted to. It seems that shallow is more suitable to them.
R. WALLER: I think they would be moving up slope in reaction to food. More food would be up slope than
down slope, and the Larger animals that require more to eat would move to an area where they might feed better.
R. SMITH: Could be.
G. HINSCH: Roy, you have two mature Stages for females?
R. SMITH: Yes.
G. HINSCH: You don't think that the second one molts again, and that isn't a terminal molt in that
instance? You think they molt to that second mature stage and then just die?
R. SMITH: The period between these first two mature stages is so extended, probably about four years or
so. Maybe they never get the chance to molt again because the third mature stage might be so extended that they
never even reach it, might possibly get taken by predators before then.
Another thing that also makes me think that they have two mature stages is that portunids have a series
of two mature stages. As Ray Namning was saying, the Geryonids are so closely related to the portunids, that
they possibly have the same pattern.
G. HISSCH: But if you assume that any animal within a single instar would vary, they would not all be the
same. Wouldn't you expect to see some sort of a double bell curve in the sizes?
R. SMITH: No, you don't.
G. HINSCH: With Chaceon several people have shown that the maximum size of females is approximately 13
and a half centimeters but they hardly ever find them beyond that.
R. ERDNA: We have recorded ovigerous females as wide as 156 millimeters.
G. HINSCH: Very few of them.
R. ERDAN: But I have never seen any bi-modal suggestion in my data.
G. HIRSCH: That's what I'm saying. If you were to have two different stages wouldn't you have a bi-
modal situation, with one instar having the largest frequency at one point and then the next instar having again
a large number of individuals?
R. SMITH: I don't think you would see that because you took data at the end of it's Life history and by
that stage there are all sorts of different growth patterns.
G. HINSCH: But in Chaceon, females release their eggs, their embryos, and internally they have fully
developed ovaries. If you consider the energy necessary for ovarian development it would seem very unlikely
that Large numbers of females are going to undergo vitellogenesis and release their larvae, with vitellogenesis
occurring at the same time as larval development and then not continue on to have another brood from those eggs
which they contain within them.
W. VAN HEUKELEN: I don't think you would see a bi-modal distribution as Tuck Hines was talking about,
possibly because of large growth increments. The only juvenile we had that was any size was 82 centimeters and
it molted to 91. That's only an eleven percent increase at the molt for that size. If you have much variation
at all it's going to wipe out a bi-modal distribution. We found with our juveniles that they started out with
about a 43 percent increase of stage one to stage two, and by the time they were going from crab six to crab
seven it was down to about 14 percent. It tooks like as size increases the increment percentage decreases.
A. HINES: You could have a declining mplt increment with increasing size so that the juveniles would have
a fairly high molt increment and the larger adults would have decreasing molt increments.
U. VAN HEUKELEN: That's what our data show.
A. HINES: That's common in xanthid and grapsid species.
P. IIAEFHER: To follow up on one of the things that Tuck Hines was saying about taking careful measurements
and observations, I haven't heard anything expressed here about observations on parasites of these crabs. I
don't know the growth rate, for example of the octolasmid barnacle, but if you see a crab that's loaded with
large octolasmid barnacles, you get some sense as to how long ago it has been since that individual has molted.
You should see the same thing with parasites in the gill chambers. It takes a little more effort and a little
bit more time to look for these things, but I think it's worthwhile in the long run.
A. HINES: The most obvious commensal with these species are the stalked barnacles that occur on the
R. EIRHAN: That not Octolasmis, it's a poecilasmid. There isn't enough known about the biology of that
species to know how fast it's growing.
P. HAEFNER: We need to get some comnensal biologists involved here too.
G. HINSCH: With one specimen there was a large polychaete worm about six inches long. I don't have the
name with me but I can get it. This was found in the gill chambers of the red crab, we never found it in
Chaceon fenneri, but they were quite common.
A. HINES: I think that you can get some information about that, but it's more qualitative information,
and I would be cautious because it's difficult to make strong inferences from that. It helps support more
direct information from the crabs and their molt stage, so I think it's worthwhile.
R. ERDMAN: Regarding both comnensalS that we just discussed, the barnacles we've collected from both
Chaceon feneri and uinauedens have been a ent to Dr. Williams in Wales, thanks to Tuck. That group appears
to be a taxonomic nightmare. And regarding the gill worms, we have collected extensive numbers of polychaetes
from Chaceon fenneri from both the east coast and the west coast. They seemed to be fairly common. Tom Perkins
from Florida DNR has identified them.
E. UENNER: We also found this particular polychaete in Chaceon fenneri in our collections.
D. ARMSTRONG: I have a question both for the fishermen and probably Bob ELner and it has to do with your
desire to predict consequences of certain actions, and this relative to the ecological role of the animal in
the community. To date the fishery has be4n very gentle, in fact not nearly big enough to have some sort of
impact, probably on the standing stock of big animals at the top of the size range. It is in fact the mining
point of view that you suggested, Bob Miller, which is to say it's right now like some of the virgin Snow crab
populations, old animals tending to inhibit growth of younger age classes. Once removed, the big animals will
obviously be a rare commodity but also will: evoke certain kinds of reactions in the population as a whole. A
tot more may grow, but to smaller sizes. Hbw does the Canadian government approach exploitation of that kind
of a fishery which is predicted to be slot in recovering, and how would fishermen want to handle it in this
particular case? We heard the suggestion of very limited entry as one type of regulation, but I guess you might
need to be prepared for the possibility that your fishery comes to an end over a fairly short time and takes
a Long time to recover.
S. INGHAN: I would like to say that if any study is going to be done in Chaceon, Bermuda would be an ideal
place to do it because of the quick incline of the slope. At 420 fathom the larger species disappeared and at
about 500 fathom another species took over. You are in close proximity to land and we have a day-time fishery,
no one really fishes at night.
A. HINES: What species is that?
S. INGRAH: Chaceon Fenneri.
A. HINES: Do you see C. guinquedens?
S. INGRAM: Yes. There are several species there but they seem to be governed by depth. The largest of
those species are at the shallower depths 4nd the smaller ones deeper. You're within a very short distance of
these depths, whereas along the continental United States one has to go many miles before depth changes. Also
the funnels of the traps may be a very good device to protect the Larger species. By restricting the size of
the funnel, you leave the larger species for reproduction. I don't know if anyone has got any comments on that.
A. HINES: So you're suggesting then that there be both an upper and a lower size limit on the catch.
S. INGHAN: Once we know the maximum size of the species that is being targeted, I think something could
be done along those lines similar to what has occurred in Maine with Lobsters. I would like to hear more
comments on that because I don't know what! effect that will have.
P. RAEFNER: One thing to add about the American lobster. We have the classic case along the east coast,
off the coast of Virginia when they discovered an offshore Lobster population there. The very large 15, 20
pound Lobsters were fished out very quickly down to five and three pounds. I lost track of the status of that
but perhaps either Bob Miller or Bob Elner can relate to that in New England and off Canada. You can very
quickly deplete the big individuals, and if Chaceon is indeed a very slow growing species, with intensive
fishing efforts you probably would see a rduction of that upper mode. Of course, I don't know if Roy Smith
has experienced that either.
R. ELMER: I think it all points to tie real importance of monitoring this fishery as it takes off. You
are looking at the number of soft shell crabs in the fishery every year and looking for other signs of
recruitment. To get back to Dave Armstong's question, until we know that recruitment we must proceed
cautiously. If it is a mining operation, there are a number of management strategies you can use. You can use
measures whereby you only fish that species every ten years or every five years. Alternatively you enclose
areas and fish one area for two years and then close it for five years. Or you could make sure your
exploitation rate is very low so you car Let very few fishermen in the fishery. There are a number of
management strategies, but it all depends pn the response of the stock harvested in terms of recruitment.
U. LIMDBERG: Getting back to one of the comments that Dave Armstrong made about the Alaskan fisheries,
that recruitment events my be occasiortl although reproduction my be regular or annual. Successful
recruitment events don't necessarily follow from that. In a comparative sense being long lived, with late
maturity and a tremendous investment in reproductive effort compared to other crabs, could it be that we are
having trouble finding juvenile size classes because this is only an occasional event? If an animal is Living
for 30 years and reproducing annually over a good portion of that time, could it be that successful recruitment
from any given individuals's brood is onlyI happening a small percentage of that time?
A. HINES: That's a distinct possibility. I think that we really don't know enough to answer that question
for sure about any of the species of Chaceoe, but we have similar cases in other species of crabs to show that's
a possibility. The Snow crab situation ard also King crab that Dave Armstrong mentioned seemed to indicate
that's a possibility. In the case of Snow crab, changes in size structure of the population are concomitant
with fishing pressure, and seems to result in differences in the mating biology and relative contribution of
different sizes to the reproductive output and reproductive success of the population. That can vary
geographically among fishing sites through the range of the species. It is something to be concerned with.
That kind of information is needed on Chaceop, but it's not something you can answer quickly; there is no simple
test for it.
R. NIELSON: I fished New England lobsters in Massachusetts for about 20 years. The question here is the
large animals and what's going to happen to them. It's been my experience that with any new resource in the
marine field, you're working on the Large 4dults-and those are taken right off the top. Then, it comes down
to a Level where you get an annual yield, 4o I really don't see a problem with that. The Larger animals are
taken right off the top of the resource. That occurred on the offshore Lobster fisheries up in New England.
The inshore Lobster fisheries which I participated in ended up so that we were taking a certain size lobster
down to a Level, and we were throwing bapk the smaller ones that were next year's stock. We were then
harvesting every year, and it stayed at that level for 20 years. I've been out of that fishery for over 18
years now and it's still at that Level, so I don't really see a problem of taking heavy, larger animals off the
top of a resource.
Secondly, the state of Maine is the olly state in New England that has the large carapace measurement to
protect the larger male and female Lobster. I don't see any purpose of it. I don't see where it's helped them,
but it probably hasn't hurt them.
A. HINES: The real concern in most fisheries management strategies is to be sure that the size
restrictions exceed the size and age at first reproduction, and that it not be just physiological reproduction
but that they're functionally able to reproduce. For example, in the Dungeness crab fishery and in most crabs,
males must be Larger than females in order to mete.' So while a smaLL male may be physiologically mature and
capable of reproducing, in fact, they are not contributing very much to reproductive output of the population.
You must have that minimum size females, fot example, related to the functional reproductive biology, not just
the age at which they become mature. We need to know a Little bit more about that in Chaceon. We don't know
enough yet. I have seen males in copulating pairs and the few data we have show males are quite a bit bigger
than the females, not just equal to the Largest size of the females.
D. ARNSTRONG: I would tend to agree that an upper size Limit doesn't seem wise or necessary in this case.
And the trick is whether or not there will be sufficient size differential between your economically viable
minimum and that of a crab which is also bied. The fact that so many people report low percent ovigery, but
at times that it's high, is somewhat trouble ome. In most other crab fisheries that are surveyed, those females
of theoretical mature size are almost always 100 percent ovigerous in season. Yet for these animals a Lot of
times tigy fractions are carrying eggs. It may just be a quirk of continuous reproduction at depth, as has been
suggested, but it also could be evidence that they don't all reproduce annually.
I was going to ask Bob Whitlatch, that if these animals are severely food limited and, considering the size
frequencies for males, the fishery crops the population to 140 millimeters, and that provokes some sort of
numerical response in terms of more smaller crabs, can you anticipate any effect that might have on the overall
R. WUITLATCH: To my knowledge I can think of no good example. A lot of times you don't see immediate
responses to predict this in terms of typical fisheries.
D. ARMSTRONG: They have got to be either worse off, better off, or no different in terms of the overall
food supply for more smaLLer animals if they have this cap of larger animals removed.
R. UHITLATCH: One would predict that there should be a response of the food resource availability as the
predators decrease, although there are otter factors involved. Fishes might replace the crabs and have a
similar sort of cropping behavior. We don't know a lot about the feeding ecologies of these deep water
organisms. By the way, an unpublished Ph.D thesis by Jim Farlow of Yale University deals with gut contents of
trawl surveys. Generally most of these laige forms are really opportunistic feeders and it's felt that they
crop their food resources very nonselectively. So the presumption here is that if you decrease one species you
might increase another species.
U. VAN HEUKELEN: I would just like to reiterate what's been said several times in terms of learning more
about the importance of juveniles, where they are and what their movements are. I think we have pretty
extensive trawl surveys on Chaceon and have only gotten very few juveniles and those were at great depths
compared to the adult population. I was interested in Roy's comment yesterday, that they found a Lot in fish
guts so they knew that they were in shallower water; it that right?
R. SMITH: That's right.
U. VAN HEUKELEI: So this dissertation might be very interesting to look at.
R. UHITLATCH: I would also reiterate several comments people have made about the importance of integrating
information that is required to understand the resource for fisheries and the importance of the genus in the
slope environment. We have a somewhat unique situation here in terms of research initiatives and funding
agencies for this sort of research. Many of the states are not going to be interested in supporting research
activities that occur in federal waters. Research could be motivated by two issues, the basic biology of the
organism and the role it plays in upper slope communities. At the same time, gain the appropriate information
that people have pointed out concerning the crab's potential as a fishery resource.
A. HINES: I would like to second that. From Ray anning's discussion of the increasingly apparent
diversity and world wide distribution of this group, what we Learn about the biology of Chaceon species in the
U.S. and off the African coast is Likely to have world-wide implications for that depth zone in the ocean. From
a basic research point of view as well as fisheries management, there are important issues. We're Learning a
Lot about that depth zone, and we're bringing new technological advances to bear on those research issues that
we haven't been able to approach in the past. In my view, it's somewhat analogous to the rocky intertidal
ecologist suddenly donning scuba gear and finding out there is a whole Lot going on below the low tide mark.
There is indeed a lot going on in the typical fishing zones that have been sampled in the past.
Secondly, there are other aspects of the biology from a community point of view, on trophic interactions,
that we haven't raised here. We've talked lot about this depth zone that seems to be consistent and distinct
when two or more species of Chaceon overlap, and that there is a vertical segregation with C. auinguedens, for
example, always found deeper than C. fenri. Well, why is that, what maintains that? It is simply some
intrinsic depth preference of temperature preference or are there biological interactions between fenneri and
luinguedens that you might expect to observe that would be competitive, either exploitative or interference
We haven't talked about competition aiong individuals. If food resources and access to mates are really
important, that would suggest why this species has long distance sensory abilities, and also potentially could
suggest a reason for the common occurrence of black scars on the crabs that might be due to aggressive
interactions, or could be just due to crabs banging into things on the bottom. We see that both on C. fenneri
and C. quinauedens and I suppose on other haceon species.
And finally, we raise the issue about what are some of the predators on these crabs. We talk about fish
preying on the juveniles, but we don't know how camon that is or how important that is to the fishery resources
on that slope. It would be worthwhile, if you fishermen catch some fish in your traps or in your trawls, to
Look at the stomach contents of those fishes and determine whether they have Little crabs in their stomachs.
W. LINDBERG: On the questions of species interactions, with our broad scale sampling in the Gulf, if it
was species interaction setting an upper limit for red crabs, then you would expect an ecological release in
the absence of C. ferneri. We don't see this in the northern Gulf where the bottom types are appropriate, with
predominant by mud-silt bottom at shallowerldepths. There are no C. fenneri there. If species interaction set
the range, then you would expect auinudens to move up, and they don't.
R. UHITLATCH: In New England we don't have fenneri, but it's been suggested that Cancer irroratus is
out competing Chacyon uifnuedens in the shallower waters. So there may be another species, maybe not a
Chaceon, that is fulfilling the role that 5. fenneri is playing.
U. LINDBERG: If it was filling the role of C. fenneri you might expect it would be sampled in the same
fashion as C. femeri, and we didn't have that. The intermediate and shallowest depths in our sample weren't
producing some replacement for C. ferneri. The C. quinquedens were simply not moving up, which suggests
something else is limiting them.
C. TRIGG: We don't see aggressive behavior when we hold the species together in overcrowded conditions.
U. LINDBERG: There may be not be cahnibalism, but with trap observations, we do see clear aggressive
behavior as they first approach the trap. There are cheliped displays, there is contact interaction, there is
a fleeing of the smaller individual, things that are characteristic of all the other crabs I've seen. If there
are Low frequencies of molting and a small proportion of the females are receptive at any given time, there
could be some fairly intensive competition among the males for mates. Given that they are incopulo for such
a long period of time, rather intensive sexual competition is suggested.
R. ERDMA: To return to bathymetric distribution, we have completed oxygen consumption measurements over
temperature ranges on Chaceon ouinguedens and Chaceon fenneri. The experiments were this fall, and I haven't
finished the analysis, but we did measure both species and both sexes over time in a respiration chamber. From
visual observations, there seemed to be a slight sluggishness at warmer temperatures with C. quinquedens. They
just don't do as well. They survive but are inactive and don't feed. Data that are published, whether from
gray literature or not, suggests an upper temperature limit. Yet, the species has been recorded from
temperatures as high as 12 degrees Celsius, but some of the gray Literature reports that above nine or ten
degrees the species begins to show potential physiological disturbances of physiological discomfort.
R. WALLER: Depth distribution is reality interesting. Sean said he didn't collect C. fenneri at depths
above 420 fathoms, and yet in the Gulf we get them at 200 fathoms which is our best sampling range.
R. ERDNAI : On the east coast when we first started to work with Dick Nielsen, we were fishing about 120
fathoms. We set traps in the Gulf at 120 fis and got one crab. On the east coast of Florida the Gulf Stream
spills onto the shelf along the Fort Lauderdale area. It would be interesting to see what the temperature is
like in the Bermuda area. Obviously finding out the physical conditions are very important.
R. MIELSON: When I was catching more crabs than I had markets for I decided to take a couple of trawls
of traps and see how far in I could catch the golden crabs. At about 600 feet I only caught a few, and inside
of 600 feet there weren't any. Beyond the hundred fathom curve, you didn't really get into crab around 118
fathoms. At that depth there were a few buj not enough to be commercially viable.
R. MILLER: Two rather extensive comments. First, distribution and abundance is what seems important for
both ecological and fisheries applications. As biologists we're not very experienced in giving density
estimates of large deep water animals. I think the funding agencies should be patient with applications, that
simply refine and develop measuring real density, and absolute density of these animals in deep water. It's
not glamorous perhaps but it is necessary.
A. MINES: Certainly the videos on the submersibles are a very good way, but very expensive way to do that.
R. MILLER: Secondly, regarding a management plan, if I were to make one, initially I would do it
exclusively from economic considerations. I would set a minimum size based on what you could sell. Don't waste
it, only catch what you can sell, independent of considerations of reproductive size. I would expect that, at
least now, there are a lot of refuges inaccessible to fishing either because of depth or because of low density
of the prey animal. I think one could fi h until you get down to a certain minimum. If the industry is
uncomfortable with that, set a tentative quota, say three million pounds for southeast Florida. If it takes
one year to get there or five years to get there it doesn't matter. When you get to two million pounds close
the fishery for five years and open it again and start over. But it's going to be, I'm almost certain, a mining
operation or very close to that. The American lobster is not, unfortunately, a good parallel because it's a
shallow water, fast growing species and these animals are not, I'm sure. You're going to fish them once and
Leave them for maybe another generation of fishermen.
R. UHITLATCH: No one has said anything about black spot disease, is that a concern? In New England it's
of great concern and it's been suggested that red crabs might be a good model to use to look at the incidence
of black spot disease.
E. WENNER: What he is talking about i not melanosis but the presence of chitinolytic lesions. We found
99 percent of the individuals that we sample had incidence of chitinolytic bacteria. In some cases it was very
extensive. It is certainly of interest that:in blue crab populations that is also beginning to show up in North
Carolina. It's also extending to South Carolina and is being picked up in Chesapeake Bay now where it is being
related to pollution. I think we definitely need to know more about why there is such a high incidence of
chitinolytic bacteria in Chaceon fenneri and Chaceon uinquedens in the deep sea.
R. UHITLATCH: It's one more motivation for studying the animal. I'm thinking if we can't interest
agencies that are interested in the organisO or the fisheries resource we might interest agencies that might
Like to use it as a monitor for pollution on the upper slope. We can broaden our base here.
A. HINES: Any other comments?
D. ARMSTRONG: Just a point of interest, I'm always curious where people get their crustacean funding.
You've been on a little bit of a roLL in this part of the world, what do you anticipate the source and
likelihood and level of funding will be? Is if all going to be federal government or will your Sea Grant and
Local states continue this for five years?
U. LIDBERG: Well, the prognosis isn't all that great. I would say we have been riding the wave of
fisheries development in the southeast and now we have a handle on this. It doesn't have that appearance of
being another King crab or Snow crab, although it can be a viable Localized or regional fishery. Motivation
from Sea Grant, National Marine Fisheries Service, and the fisheries development view has probably run its
D. ARMSTROhG: That gets back to Bob Uhitlatch's comment of hooking the wagon to other ecological types
of studies and agencies to fund it.
E. LENNER: I have that distinct impression too that we were able to acquire a fair amount of funding
through the region. This type of research takes a lot of funding. Just from my own experience, I received
funding from five different agencies, and put it all together into one package which required a great deal of
effort. But it required a great deal of ioney to be able to do the work. What I'm sensing now is that with
golden crab being the only topic of directed research efforts, I don't think we're going to be as successful
in getting that funding. These species aee going to have to be looked at in a more ecological or community
role, as opposed to golden crab being the sole focus of the research.
W. LINOBERG: That's part of the agenda in bringing so many different people from different regions and
different viewpoints together. We have the opportunity to forge interdisciplinary or multi-investigator
approaches to the broader scale ecological questions; that's in all of our best interests, especially when
viewed on the comparative basis that Ray Manning has given us, and considered in the broader context of other
A. HULBERT: Certainly our research center is very interested in this problem. A large part of the reason
for participating in this workshop is to get a multi-disciplinary group Like this together. The center in the
past, as Betty and Bill know, has been effective in providing the equipment and utilizing that as a seed along
with other kinds of funding like Sea Grant and state agencies. Certainty from our point of view, the funding
that we're looking at now, and the research agenda, is for big scale projects. The kinds of things that are
fundable are Gulf of Mexico ecosystems versus South Atlantic ecosystems, and what functions are involved, and
the integration of physical oceanography With larval recruitment processes. Those are very important things
we can do. We have very good reason to reach out to marine geologists and hydrologists, oceanographers, in
terms of funding. Put your interests in context of a bigger plan, a multi-interdisciplinary study, and use it
as a seed to get together and go forward.
U. LINDBERG: That perhaps is the be4t wrap up to have. Something to go home with, a challenge to work
with. I would like to thank all of you for taking the time out of your schedules to come here and enjoy the
Florida sunshine. We formally stand adjourned.
SUMMARY OF RESEARCH NEEDS AND OPPORTUNITIES
Kelly et al. proposed a model for C. auinauedens larval
transport in surface waters which was supported inferentially here
by R. Smith for C. marital and Lindberg et al. for C. fenneri. As
noted by W. Van Heukelem, rapid larval development rates at warmer
surface water temperatures should favor the restricted geographic
distributions of geryoni4 species reported by R. Manning. Is
vertical larval migration and surface water transport the rule
among geryonid crabs? If So, what are the-general implications for
recruitment processes and life history strategies of these crabs
and associated fauna.
Juvenile geryonid crabs rarely appear in samples, and then
mostly from deeper collections. This pattern led previous authors
to hypothesize that settlement occurs deep on the continental slope
with subsequent up-slope migration during ontogeny. As noted by
A. Hines, one alternative hypothesis is that settlement occurs
across the slope followed by higher natural mortality of juveniles
(e.g., from predation) at shallower depths. Another possibility,
derived from comments by W, Van Heukelem concerning juvenile growth
rates at different temperatures, is that crabs which settle into
deeper zones are locked into juvenile size classes for many more
years and are, therefore, more likely to appear in samples, given
low recruitment rates and markedly different growth rates across
the bathymetric range of a species. What are the settlement
patterns of geryonid crabs with respect to depth? What are the
subsequent development and mortality rates, and how do they vary
Similarly, if larval transport by surface currents as proposed
by Kelly et al., R. Smith, and Lindberg et al. is confirmed, to
what extent should we expect settlement to be concentrated
geographically or with respect to hydrographic features?
In general, growth rates (increments and molt frequencies) and
age at first reproduction are poorly known for geryonid crabs.
Accurate, detailed molt staging should be incorporated into future
sampling regimes, while controlled laboratory experiments to test
effects of ecological variables are particularly desirable.
A terminal molt with mating in the hard condition was suggested
by G. Hinsch based on histological analyses, but this was countered
by R. Smith, R. Erdman et al., and H. Perry et al. with field data
and direct observations of captive pairs. As noted by A. Hines,
resolution of such questions is possible with careful attention to
detail, e.g. the occurrence of limb buds on ovigerous or post-
At the population level, C. fenneri exhibits an seasonal
reproductive cycle, C. aritae year-round reproduction, and C.
quincuedens a protracted seasonal to continuous reproduction
perhaps dependent on geographic location. Why should some geryonid
species or populations show circannual periodicity while others do
not? Regardless of cyclic or acyclic reproduction, only a low
percentage of females are ovigerous, or pre- or post-molt at any
given time, suggesting that individual reproduction is not
necessarily annual. R. Erdman and N. Blake hypothesized a biennual
reproductive cycle for individual female C. fenneri, while A. Hines
suggested reproduction on an annual cycle or longer contingent on
adequate energy reserves. Comparative studies and experimentation
are needed to resolve questions of this basic life history trait.
R. Elner et al. and H. Perry et al. reported that copulation
and mate guarding lasted many weeks for C. auinauedens and C.
fenneri, respectively. When combined with a potentially low
incidence of receptive females, this indicates extreme levels of
intrasexual competition among males for mating opportunities.
Lindberg et al. inferred Seasonal shifts in the bathymetric ranges
of male and female C. fenheri, and that large males carried mated
females downslope to strata with low population densities to avoid
competing males and minimize disturbance during mating. Seasonal
movements, encounter rates among potential mates and competitors,
movement by mated pairs, and takeover attempts all need to be
documented to test geryonid mating strategies.
Geryonid species apparently differ in habitat preferences, with
consequences to overall ecological comparisons and linkages to
physical processes. The red crabs C. maritae and C. auinquedens
have been found exclusively on soft bottoms, while Lindberg et al.
and Wenner et al. reported greatest densities of golden crab, C.
fenneri, from hard bottom habitat. R. Manning noted differences
in leg dactyl structure consistent with weight distribution on soft
bottom versus climbing ability on hard bottom topography. R. Henry
et al. found that C. auiniuedens were slightly more tolerant to
hypoxia than C. fenneri. Whitlatch et al. attributed substantial
bioturbation of soft bottom to the activities of C. cuincuedens.
Basic ecological questions concerning physiological ecology,
refuges and foraging habits, trophic dynamics and community
relationships remain largely unanswered. Given the predominance
of geryonid crabs on the upper continental slope, resolution of
these questions should illuminate much about general slope ecology.
Related to foraging habits of these crabs, trapping efforts have
been successful despite low population densities revealed through
submersible transects. Geryonids apparently exhibit particularly
keen chemosensory and prientational capabilities, and great
motility. This and habitat relationships raise questions about
home ranging versus nomadism among species, and the relative
importance of bonanza food falls versus benthic predator-prey
relationships. The practical consequences of such questions
concern effective areas fished by traps and the resiliency of
fishing grounds to persistent fishing pressure.
The questions above pertain mostly to life history strategies
and fundamentals of geryonid ecology. In part, this reflects
interests of the workshop organizers, many participants, and
fisheries interests. Equally valid, however, are questions of
basic physiology of deep-welling organisms, biogeography and
systematics, or parasitology and symbiosis. Regardless of
discipline, the recent systematic revisions within Geryonidae by
R. Manning and Holthius reveal taxa ripe for comparative studies.
Industry needs for harvesting, processing and marketing
information have been addressed with modest research not thoroughly
covered in this workshop, Nevertheless, these areas, plus basic
economic considerations, could and perhaps should be compiled with
existing biological data #nto a draft fisheries management plan for
Geryonid fisheries of the southeastern United States.
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Dr. David Armstrong
School of Fisheries
University of Washington
Seattle, Washington 98195
Dr. Norman Blake
Department of Marine Science
University of South Florida
140 7th Ave. South
St. Petersburg, Florida 33701
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Marine Research Institute
Florida Department of Natural Resources
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Invertebrates and Marine plants Division
Fisheries Research Branch
Department of Fisheries and Oceans
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Department of Marine Science
University of South Florida
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Rochester Institute of Technology
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Smithsonian Environmental Research Center
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Department of Biology
University of South Florida
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NOAA National Undersea Research Center
University of North Carolina at Wilmington
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Georgia Sea Grant Extension Program
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