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Materials and methods
CHARACTERIZATION OF A MARINE TURTLE AGGREGATION IN THE BIG
BEND OF FLORIDA
WILLIAM J. BARICHIVICH
A THESIS PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE
UNIVERSITY OF FLORIDA
William J Barichivich
To the late Captain Edgar "Yellowlegs" Campbell.
I would like to thank my committee, Drs. Raymond R. Carthy and C. Kenneth
Dodd, Jr., for their patience with me during my many distractions. My "unofficial"
committee of friends and coworkers, Dr. Jeffrey R. Schmid, Dr. Lora L. Smith, Dr. Steve
A. Johnson, Howard L. Jelks, and Dr. Kevin G. Smith, contributed more than they may
I thank the Fates for making my path cross with Jeff Schmid. Through his tutelage
I gained an appreciation of the nuances of turtle fishing he learned from Larry Ogren and
the last of the commercial fishermen in Cedar Key. One fisherman, Edgar Campbell, and
his family, were especially generous and enlightening to all things "Old Florida,"
although I never did learn my nickname if I ever earned one.
It should not be forgotten that Dr. Cathi Campbell started this project and I am
indebted to her for that. Without the selfless dedication of Mike Randall, Jennifer
Staiger, Duane Houkom, Les Parker, Gary Hill and innumerable University of Florida
and Long Island University students, the fieldwork would have ground to a halt.
This research would not have been possible without the support of Drs. Churchill
B. Grimes and Kenneth J. Sulak. Funding for this project was provided by the National
Marine Fisheries Service Panama City Office and equipment and logistics by the United
States Geological Survey Florida-Caribbean Science Center.
I am grateful to my parents, Pat and Dave, and my maternal grandparents, Pat and
Bill, for helping me become who I am, and always letting me do what I thought was right
regardless of how they felt about my decisions. Finally, I am thankful for my fiancee,
TABLE OF CONTENTS
A C K N O W L E D G M E N T S ................................................................................................. iv
LIST OF TABLES ......... .. .. ....................................... .... ... .............. viii
LIST OF FIGURES ......... ......................... ...... ........ ............ ix
A B ST R A C T ................. .......................................................................................... x
1 IN TRODU CTION ................................................. ...... .................
2 M ATERIALS AND M ETHOD S ........................................... ........... ............... 3
Stu dy A rea ......................................................................... . 3
Data Collection ........................................ ........3
Biom etric and N on-biom etric D ata ........................................ ........................ 5
D ata A nalysis.................................................... 6
3 R E S U L T S ............................................................................................. 1 1
Captures and Effort .................. ........................ .... ... ...... .............. .. 11
R ecaptures and Local M ovem ents..................................................................... .... 12
Seasonal and annual size distributions ............................................ ............... 14
C arapace R egression E quations..................................................................................14
Growth Analysis ...................................... ........................... .... ......... 15
4 DISCUSSION ....................................................... ........... .... .......... 29
O ntogenetic H habitat .................. ................................. .. .. .. .. .............. 30
M igratory B behavior ........................ .............. ............. ...... .......... 1
S ite F id e lity ........................................................................................................... 3 2
Temporal and Geographic Shift in Size.................................... ...................... 34
G ro w th ............................................................................................. 3 5
H e a d sta rts .......................................................................... 3 6
F future R research ....................................................................... 39
L IST O F R E F E R E N C E S ...................................... .................................... ....................4 1
B IO G R A PH IC A L SK E TCH ...................................................................... ..................46
LIST OF TABLES
3-1. Annual set-net effort (km-hr) and CPUE (turtles/km-hr) by species for
Apalachee and Deadman Bay from 1995 to 1997..................................................17
3-2. Proportion of marine turtle captures made in Deadman Bay from 1996 to 1999
by gear type and species .................. ............. ........ ... ....................... 18
3-3. Identification, release, and subsequent recapture data ofNMFS headstart
K em p 's ridley turtles................................................ ... .... .... .......... 19
3-4. Seasonal water temperatures and Kemp's ridley turtle, Lepidochelys kempii,
carapace lengths in Deadman Bay from 1996-1999 ........................ .............. 20
3-5. Formulae for converting between straight-line and curved carapace
measurements of Kemp's ridley turtles. .......................... ............... 21
3-6. M ean annual growth rates of Kemp's ridley turtles ..............................................22
3-7. Estimated values of asymptotic length (a) and intrinsic growth rate (k) from
nonlinear regression of von Bertanlanffy growth interval equation for Kemp's
ridley turtles .............. ........................ ......... ......... ... .. ......... 23
LIST OF FIGURES
2-1. Map of Florida Big Bend (black box) showing Apalachee (green box) and
D eadm an Bays (blue box).......................................................................9
2-2. USGS R/V Plastron prior to outfitting with a tower.. ..............................................10
3-1. Length-frequency distributions ........................................... ......................... 24
3-2. Example of fibropapillomatosis exhibited by a green turtle, Chelonia mydas,
from D eadm an B ay. ........................... ................ ......................... 25
3-3. Photograph of biofouling by the sea turtle barnacle. .............................................26
3-4. Annual relative size composition of Kemp's ridley turtles, Lepidochelys kempii,
captured in Deadman Bay from 1996 to 1999. .............................. ......... ...... .27
3-5. Kyphotic green turtle, Chelonia mydas, captured in Deadman Bay ......................28
Abstract of Thesis Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Master of Science
CHARACTERIZATION OF A MARINE TURTLE AGGREGATION IN THE BIG
BEND OF FLORIDA
William J. Barichivich
Chair: Raymond R. Carthy
Major Department: Wildlife Ecology and Conservation
The Kemp's ridley sea turtle, Lepidochelys kempii, is critically endangered. Away
from the nesting beach, little is known about the species. Data from all stages of their life
cycle are critical to understanding their recovery. Therefore, this in-water study was
initiated to fill in gaps in our knowledge about the juvenile and subadult ridleys
inhabiting the nearshore waters of the northeastern Gulf of Mexico.
Between 1995 and 1999, 159 individuals of three species of marine turtle (L.
kempii, Caretta caretta, and Chelonia mydas) were captured in Apalachee and Deadman
bays, Florida. Captures were dominated by 20 to 40 cm standard straight carapace length
Kemp's ridleys. Ninety-six percent of all captures were made in Deadman Bay and no C.
caretta were captured in Apalachee Bay.
Caretta caretta and C. mydas were captured during the warmer months and L.
kempii was captured from March to December, although fewer captures were made in
cooler months. No turtles were captured or observed when water temperatures were less
than 200 C. Reasonable estimates of annual growth for ridleys ranged from 1.25 to 8.92
cm. The high degree of short-term recaptures of Kemp's ridleys in Deadman Bay
indicates a high level of site fidelity within a season and recaptures between seasons may
suggest more long term affinity to the area.
This is the only study of marine turtles to include Deadman Bay and the results
show the area has been overlooked as an important developmental habitat for the three
species captured. Heavy industry and coastal developmental potentially threaten the
health of the area and the role it plays in the recovery and maintenance of these federally
The Kemp's ridley (Lepidochelys kempii Garman, 1880) is the most endangered of
the seven extant marine turtle species (Ross et al. 1989). The US Fish and Wildlife
Service (USFWS) and the National Marine Fisheries Service (NMFS) estimate the
breeding population at 1,500 to 3,000 individuals. The population has been reduced from
approximately 40,000 observed nesting on one day to no more than 700 nesting annually
(Magnuson et al. 1990, USFWS and NMFS 1992). Conservation measures for the
species have focused on the protection of the nesting beach, captive rearing (head
starting), and the implementation of turtle excluder devices (TEDs) on shrimp nets.
Despite the mandatory use of TEDs, annual incidental take of Kemp's ridleys by shrimp
trawls has been estimated between 500 and 5,000 (Magnuson et al. 1990). Lack of
knowledge about early life stages of the Kemp's ridley sea turtle currently hinders
recovery efforts for this federally listed species.
The recovery plan for the Kemp's ridley (U.S. Fish and Wildlife Service and
National Marine Fisheries Service (NMFS), 1992) identified in-water, live capture
studies as a Priority I Task for determining seasonal use of nearshore habitat by juveniles
and subadults. The U.S. Geological Survey, Biological Resources Division (USGS-
BRD) targeted marine turtles on their Biological Resource and Management Issues
agenda. In addition, an independent scientific review team (Eckert et al. 1994)
recommended that research efforts for Kemp's ridley be focused on a large-scale mark
and recapture program that should, in part, provide information on growth and survival
rates, size-frequency distributions, sex ratios, habitat use, and movement patterns for wild
and headstarted juvenile turtles.
Juvenile and subadult Kemp's ridleys use the shallow nearshore waters of the north
and central West Coast of Florida (True 1887, Ogren 1989, Schmid and Ogren 1990,
Rudloe et al. 1991, Schmid and Ogren 1992, Schmid 1998, Schmid and Barichivich
2005, Schmid and Barichivich 2006). In the nearshore waters of Cedar Key, Florida,
Schmid and Ogren (1990, 1992, Schmid 1998) conducted a long-term (1986-1995) study
of wild subadult Kemp's ridleys. This is one of few studies to characterize the population
of Kemp's ridleys using developmental habitat in the region.
The current study was undertaken as part of a collaborative effort between the
NMFS, Southeast Fisheries Science Center, Panama City, Florida, and USGS-BRD,
Florida Caribbean Science Center, Gainesville, Florida, to establish sampling methods for
development of population indices for monitoring Kemp's ridleys in the Florida
Panhandle. The goals of the NMFS/USGS ridley research in the Florida Big Bend area
were to define patterns of occurrence, relative abundance (vis-a-vis other sea turtle
species), growth rate, sex ratio, size frequency distribution, habitat use, and movement.
MATERIALS AND METHODS
Sampling was conducted from May 1995 to August 1999 from Apalachee Bay to
Suwannee Sound within the Florida Big Bend. The specific areas targeted for sampling included
Apalachee and adjacent bays, and two areas in Deadman Bay. The majority of netting in 1995
was conducted in and around Dickerson and Levy bays, adjacent to western Apalachee Bay.
Netting in subsequent years was conducted at the Pepperfish Keys and Fishermans Rest in
Deadman Bay (Figure 1). Much of the Apalachee Bay is characterized as estuarine habitat with
oyster beds, seagrass, sand, and mud patches throughout. Seagrass beds with sand substrate
characterize the more southern capture sites in Deadman Bay. Several significant paleo-river
channels bisect the broad seagrass shelf underlying the bay. Kemp's ridleys are known to utilize
these bathymetric features to move in and offshore while exploiting the abundant prey along the
edge of the shallower grass flats (Carr and Caldwell 1956, Rudloe et al. 1991, Schmid 1998).
Sampling was concentrated in Deadman Bay due to the abundance of Kemps ridleys, clear water,
and the high capture rate. The bulk of effort in 1998 and 1999 was concentrated north of the
Steinhatchee River channel and south of Fishermans Rest (Figure 1).
A 7 m Tremblay flat-bottomed boat (birddawg) was used for all research activities. This
shallow draft tunnel-hulled skiff was outfitted with a 2.25 m tall gunwale mounted tower to aid
in the observation of marine turtles (Figure 2). The large aft netwell and forward mounted
outboard motor allowed the rapid deployment of nets at any speed as well as the easy retrieval of
turtles and swimmers without fear of entanglement in the propeller.
Several capture methods, including set-netting, strike-netting, and hand capture, were used.
All proved successful but varied in efficacy depending on conditions. The set-netting technique
and gear employed was similar to that of the former commercial Cedar Key-Crystal River fishery
(Caldwell and Carr 1956). A 50 m x 6 m multi-filament nylon net (25 cm bar) was stretched
across a natural channel and monitored. Each end was held in place by a large (approximately
25 kg) kedge (fisherman's) anchor attached by a 15 m polypropylene bridle. Closed-cell foam
buoys were attached along the headline to supplement floatation and serve as navigational aides.
The net was checked for turtles hourly. Any turtles observed in the net were immediately
removed. These methods were consistent with those of other contemporary fishery independent
in-water marine turtle studies in the nearby area (Schmid and Ogren 1992, Schmid 1998).
Strong tides and a high frequency of boat activity hindered set-netting. It was therefore best to
conduct this type of sampling during neap tides, on weekdays, and early in the summer (< July 1)
before the recreational scallop season commenced.
Active capture techniques also were utilized to capture turtles, especially when conditions
for set-netting were poor. Two observers, one port and one starboard, stationed in the tower
looked into the water with polarized glasses while a third person piloted the boat. When a turtle
was spotted, a floating marker was dropped at that point. After marking the spot where the turtle
was seen, the observer continued to watch the often stationary turtle while directing the boat
pilot. The pilot maneuvered the boat alongside the turtle and the second observer released the
net on the pilot's command. The pilot circled the turtle as the net ran off the stem. Turtles
generally became entangled in the net and were easily removed by observers in the boat. A
snorkeler removed individuals that were encircled but continued to avoid becoming entangled.
Initially a 150 m x 6 m nylon net (25 cm bar, very similar to the set-net except for length) was
used for strike-netting but was replaced by a 150 m x 2.5 m monofilament net (10 cm bar) for its
superior ability to prevent the escape of small turtles. Hand capture (rodeo) was generally
reserved as a last resort if a turtle escaped entanglement in the strike-net or if the water was too
shallow (< 0.25 m) to run the boat. After pursuing an individual for a short distance a diver
jumped off the boat onto the turtle while the remaining crew returned in the boat to pick up both
turtle and diver.
Biometric and Non-biometric Data
Turtles were checked for scars from previous tagging and for living, flipper, and PIT
(Passive Integrated Transponder) tags. Living tags appeared as a white patch near the center of a
carapacial scute. Living tags are formed by transplanting a piece of lighter colored plastral tissue
into a scute on the darker carapace at different scute locations to distinguish between year classes
(Fontaine et al. 1993). The NMFS Head-start Program in Galveston, Texas, has performed this
procedure on all head-started Kemp's ridley turtles since 1984. If flipper tags were not present,
#681 inconel flipper tags (National Band and Tag Co., supplied by NMFS, Miami, FL) were
placed on the proximal trailing edge of both anterior flippers of all marine turtle species
captured. If a PIT tag was not detected by scanning the anterior flippers and shoulder region,
one was placed subcutaneously in the dorsal surface of the left anterior flipper of all Kemp's
ridleys. Any biofouling was removed from the tags of recaptured animals to aid tag retention.
Measurements including carapace and plastron lengths and widths, and overall body mass
for each individual were recorded. The carapace measurements included both curved and
straight-line measurements for the following: 1) standard carapace length (from the precentral
scute at carapace midline to posterior margin of postcentrals), 2) minimum carapace length, 3)
notched carapace length, and 4) total carapace length (see Pritchard et al. 1983 for full
descriptions and diagrams of carapace measurements). Curved and straight-line carapace widths
were measured at the widest point of the dorsal side. Tree calipers (95 cm or 40 cm length) were
used for all straight-line measurements and a 150 cm flexible tape measure was used for all
curved measurements, all to the nearest mm. Using hanging Pesola spring scales, turtles
weighing less than 2 kg were weighed to the nearest 0.02 kg, between 2 and 20 kg were weighed
to the nearest 0.2 kg, and those greater than 20 kg to the nearest 0.5 kg. To minimize error in
extrapolating growth rates, all measurements were made by a single observer throughout any
single season (Bjomdal and Bolten 1988). Photographs were taken of the full body of each
individual (carapace and plastron) and of any abnormalities. When possible, blood was drawn
from Kemp's ridleys for radioimmunoassay (RIA) sex determination (Geiss et al. 2005).
Salinity and water temperatures were obtained at the time of capture using a YSI model 30
meter. Depth, tidal vector and velocity, and substrate and vegetative composition were also
recorded. Position was recorded at each capture location, as Universal Transverse Mercator
(UTM) coordinates, using a real-time differentially corrected Magellan NAV DLX-10 Global
Positioning System with accuracy better than 10 m.
Length-frequency distribution and species composition of Kemp's ridley, green, and
loggerhead turtles were assessed for each of the two major embayments surveyed. Further
analyses of Kemp's ridley capture data were performed to address potential gear biases,
morphometrics, growth rates, and seasonal occurrence and habitat characteristics. Standard
straight-line carapace length (SSCL) was used to evaluate size distribution, gear, and growth.
Unless otherwise noted, means ( x) are followed by + one standard deviation.
Set-netting effort (CPUE) was standardized (Shaver 1994) with the formula:
E Nets x Length Hrs
E = ------ lOOOs
where E = the netting effort in hours fished by km tangle net
Nets = the number of tangle nets fished
Length = the length (m) of a net; and
Hrs = the number of hours fished
Morphometric relationships of Kemp's ridleys were examined by regressing carapace
length on carapace length and log-transformed body mass. Kemp's ridley carapace conversion
formulae were calculated by regressing paired straight-line and curved carapace lengths.
Annual growth rates were calculated with the following formula:
G = ALength 365
G Days )
where G = the growth rate in cm/yr;
A Length = difference between the length at recapture and the length at initial capture
Days = the number of days at large.
Kemp's ridley growth rates were compared by duration of intercapture period, season, and
size class at initial capture. The von Bertalanffy growth interval equation (Fabens 1965):
CL2 =a (a CL )e-kt
where CL2 = the carapace length at recapture
a = the asymptotic length
CL1 = the carapace length at first capture
k = the intrinsic growth rate
t = the time in years between captures
was fitted to the recapture data using a nonlinear least squares regression procedure (SAS
Institute Inc. 1998).
0 2 4 8 12 16
,i m= Kilometers
Figure 2-1. Map of Florida Big Bend (black box) showing Apalachee (green box) and Deadman
Bays (blue box). Note that multiple individuals and species were captured at set-net
locations and individual turtles were captured at species specific hand and strike-net
I | '. .f"
Figure 2-2. USGS R/V Plastron prior to outfitting with a tower. This 7 m Tremblay "birddawg" was the primary capture vessel over
the course of the study. Note nylon strike net in the aft netwell and release float (aka "let-go") next to the observer.
Captures and Effort
One (16%) green and five (84%) Kemp's ridley turtles were captured in Apalachee Bay
over 18.45 km net hours. All turtles in the Apalachee Bay area were captured in set-nets with the
maximum Kemp's ridley CPUE of 2.1 turtles/km net hr in 1996 (Table 3-1). The green turtle
(Chelonia mydas Linnaeus, 1758), measured 37.3 cm SSCL and the Kemp's ridleys ranged from
28.6 to 38.4 cm SSCL ( x = 34.0 + 3.4 cm, Fig. 3-1). Netting in this area was conducted June
through October 1995, August 1996, and July 1997. The green turtle capture occurred in July
1997 and Kemp's ridleys were captured from July through October 1995, and August 1996.
Eleven (6.9%) loggerhead (Caretta caretta Linneaus, 1758), 27 (17.0%) green, and 121
(76.1%) Kemp's ridley turtles were tagged during netting activities in Deadman Bay. In addition
to 8.3 km net hr of set-net effort, 100 days of active searching were conducted, including
opportunistic captures while traveling to and returning from set-net sampling. Though set-
netting was successful for capturing all species, 54.5, 66.0 and 88.3% of loggerhead, green and
Kemp's ridley captures were made by rodeo and strike-netting (Tables 3-1 & 3-2). Four capture
techniques, large-mesh nylon set-net, large-mesh nylon strike-net, monofilament strike-net, and
hand capture, were compared. Carapace lengths of Kemp's ridley captured with the nylon nets,
regardless of technique, were significantly greater than those captured with the other methods (F
= 5.575, P = 0.001). Loggerhead turtles ranged from 23.7 cm to > 1 m SSCL ( x = 63.5 24.7
cm, excluding two individuals too large to measure straight-line), green turtles from 27.9 to 70.7
cm SSCL ( x = 42.2 9.8 cm), and Kemps ridley turtles from 20.7 to 64.2 cm SSCL ( x = 35.0
+ 8.8 cm, Figure 3-1). RIA of 3 loggerhead blood plasma samples collected in 1996 yielded a
sex ratio of 1M: 0.5F. Four of the 11 loggerheads captured were potentially adults, yet only one
individual could be positively identified as a male by its proportionally larger tail. Gender could
not be determined for any of the green turtles based on external characters because they were all
immature. However, RIA of 8 individuals revealed a 1M: 7F sex ratio. RIA of 12 blood plasma
samples from immature Kemp's ridley collected in 1996 resulted in a 1M: 2F ratio, and a later
analysis of 48 Kemp's ridleys collected from 1997 to 1999 suggested a more highly skewed ratio
of 1M: 3.7F (Geis et al. 2005). Only one Kemp's ridley captured was large enough (64.2 cm
SSCL) to be considered adult. This Galveston NMFS lab headstart appeared to be female.
Netting in Deadman Bay was conducted March to December: loggerheads were captured
from March to August, green turtles from April to December, and Kemp's ridleys from March to
December. The incidence of fibropapillomatosis in green turtles from this area varied from year
to year; 55% in 1996, 18% in 1997, and no observations in the final two years. Additionally, the
severity of fibropapillomas ranged from small lesions of the nictitating membrane to large
(approximately 15 cm diameter by 6 cm thick) tumors on the plastron, head and limbs (Figure 3-
Recaptures and Local Movements
One green turtle and 14 Kemp's ridleys, excluding NMFS headstarted turtles, were
recognized as individuals previously marked in this study. All recaptures were made in
Deadman Bay north of the Steinhatchee River channel with the exception of a single ridley
recapture in the southern extreme of the bay near the Pepperfish Keys. Twenty-one percent of
the Kemp's ridleys recaptured exhibited flipper tag loss. All individuals at large for more than
158 days lost at least one of their two flipper tags, resulting in a 17% loss of individual tags
applied to ridleys. Heavy biofouling by the sea turtle barnacle Chelonobia testudinaria
(Linnaeus, 1758) was documented after 55 days (Figure 3-3) and significant (> 1cm diameter)
growth was observed in as few as 20 days. Three PIT tags were "lost" from two small (<25cm
SSCL) Kemp's ridleys over multiple recaptures. After the apparent loss of these PIT tags,
Nexaband SC was used to seal injection site wounds after tagging.
The sole green turtle recaptured was at large for 357 days. Kemp's ridley recapture
intervals ranged from 2 to 370 days. The green turtle was recaptured 720 meters (m) from the
original point of capture and Kemp's ridley intercapture distances spanned 168 to 2466 m. There
was no relationship between the number of days at large and the distance between capture
locations (r2 = 0.0566, n = 21). In 1998 three Kemp's ridleys from the area between the
Steinhatchee River channel and Fishermans Rest were recaptured multiple times. One individual
tagged in June was recaptured in July, August, and September (88 day duration). Another turtle
tagged in June was recaptured in August and December (158 day duration). The third turtle was
tagged in August, recaptured later in the month, and again in December (112 day duration).
In addition to the 14 Kemp's ridleys marked and recaptured in this study, four NMFS
Galveston Lab headstart turtles were recaptured. In 1995, three coastal-benthic juveniles (28.6,
36.1, and 38.4 cm SSCL) were recaptured in Apalachee Bay (see Campbell 1996). Six days after
the initial recapture, the largest of the three turtles was recaptured a second time at the same
location. The two smallest turtles had readable PIT tags and had been released near Panama
City, Florida. In May of the following year an adult female (64.2 cm SSCL) was recaptured at
the Pepperfish Keys. Based on the locations of living tags, the turtles had been repatriated for
323, 885, 1206 and at least 2388 days respectively (Table 3-3; Fontaine et al. 1993, Caillouet
Seasonal and annual size distributions
Mean seasonal water temperatures for Deadman Bay capture locations were calculated by
date: spring (Mar-May), summer (Jun-Aug), fall (Sep-Nov), and winter (Dec-Feb, Table 3-4).
Loggerheads were captured in water temperatures between 20.7 and 32.7 C, green turtles from
22.2 to 32.7 C, and Kemp's ridleys exceeding 19.7 and less than 34 C. Similarly, loggerheads
were captured in salinities ranging from 13.3 to 31.3 parts per thousand (ppt), green turtles
greater than 15.0 but less than 31.7 ppt, and Kemp's ridleys exceeding 9.0 but no more than 35.0
ppt. Carapace lengths of Kemp's ridleys captured in Deadman Bay were pooled by season and
compared. There was no significant effect of season on the size of the turtles captured
(ANOVA, F = 2.084, P = 0.105). No significant differences in SSCL between seasons were
detected with a Bonferroni multiple comparison procedure.
The annual relative size distribution of Kemp's ridley turtles captured in Deadman Bay was
dominated by the 30-40 cm size class in all years (Figure 3-4). The mean annual SSCL of ridley
turtles captured in Deadman Bay did not vary between years (ANOVA, F = 1.861, P = 0.139),
and the annual carapace length distributions did not differ when compared using the Kolmogrov-
Smirnov two-sample test.
Carapace Regression Equations
Straight-line carapace width and length were strongly correlated (r = 0.993, n = 137) for
Kemp's ridley turtles. The following equation describes the relationship:
SCW= -3.10 + 1.03 (SSCL).
Again, a strong relationship (r = 0.995, n = 137) exists for natural log transformed mass-to-
length data resulting in the equation:
In WT= -8.50 + 2.91 (In SSCL).
Straight-line and curved carapace length measurement conversion equations were
calculated to allow for comparison with other studies that may use different measuring
techniques (Table 3-5).
One green turtle was recaptured during this study. This kyphotic individual was initially
36.7 cm SSCL and grew 1.3 cm over 357 days resulting in an annual estimated growth rate of
1.33 cm/yr (Figure 3-5). Between 1997 and 1999, 14 Kemp's ridley turtles were recaptured a
total of 21 times in Deadman Bay, allowing for the calculation of 21 annual growth rates. The
small proportion (14%) of long-term recaptures and short duration of within-season recaptures
( x = 61.2 43.9 days) potentially confounds analysis of growth by season and size due to the
amplification of measurement errors in the extrapolation of annual growth rates. The effect of
this can be observed in the precipitous decrease in standard errors of annual growth rate with an
increase in recapture interval. Although mean annual growth rate within and between seasons
did not vary statistically (ANOVA, F = 0.76, P = 0.396), there appears to be a slight tendency
toward greater growth within a season. Mean growth rate did not vary with size class of the
turtle (ANOVA, F=1.30, P=0.299) but showed a numeric trend for 30-40 cm SSCL turtles to
grow faster than those in the 20-30 cm SSCL size class (Table 3-6).
Each recapture interval was fitted with the von Bertalanffy growth interval equation.
Asymptotic length estimates ranged -784.2 to 230.8 cm and intrinsic growth rates estimates from
0.00417 to 0.0198 (Table 3-7). The best fit growth model with the lowest residual error was that
of all captures, although it did not produce the most realistic asymptotic length. Marquez (1994)
reported the mean carapace length of 65 cm for nesting females. Estimates of asymptotic length
approaching this figure could be considered the most biologically realistic. Therefore the model
for recaptures exceeding 90 days would fit best.
Table 3-1. Annual set-net effort (km-hr) and CPUE (turtles/km-hr) by species for Apalachee and Deadman bays from 1995 to 1997.
LK=Lepidochelys kempii, CC=Caretta caretta, and CM=Chelonia mydas.
Apalachee Bay Deadman Bay
Year (months) Effort LK/km-hr CC/km-hr CM/km-hr Effort LK/km-hr CC/km-hr CM/km-hr
1995 (Jun-Sep) 17.57 0.28 0 0
1996 (May-Sep) 0.48 2.08 0 0 5.72 1.05 0.52 0.52
1997 (May-Jul) 0.4 0 0 2.5 2.58 1.94 0.39 2.33
Table 3-2. Proportion of marine turtle captures made in Deadman Bay from 1996 to 1999 by
gear type and species.
Caretta Chelonia Lepidochelys
caretta mydas kempii
n= 11 n = 28 n= 145
Rodeo 0.00 3.57 15.17
strike-net 36.36 35.71 59.31
strike-net 18.18 28.57 13.79
Set-net 45.45 32.14 11.72
Table 3-3. Identification, release, and subsequent recapture data ofNMFS headstart Kemp's ridley turtles, Lepidochelys kempii,
captured and identified in this study. Original NMFS tags in bold.
NMFS NMFS N-T growth
Flipper tag Living tag Year release Capture release Capture (cm) at rate
numbers PIT location class date date location location recapture (cm/yr)
SSN801 2242190B60 2nd left 1991 19May92 7Sep95 32 km off Fiddler's 38.4 Unknown
SSN802 costal 13Sep95 Galveston, Point size at
scute TX release
SSH019 1F09221422 3rd left 1993 250ct94 13Sep95 off Panama Fiddler's 28.6 4.6
SSN803 costal City, FL Point
SSN806 7F7D31127A 3rd right 1992 18May93 200ct95 off Panama Fiddler's 36.1 18.7
SSN807 costal City, FL Point
SSN808 2242253909 4th vertebral 1986 NA 15May96 NA Pepperfish 64.2 NA
SSN809 scute Keys
Table 3-4. Seasonal water temperatures and Kemp's ridley turtle, Lepidochelys kempii, carapace
lengths in Deadman Bay from 1996-1999 (standard deviation given in parentheses).
Season Mean water temperature length n Size range
Spring 26.1 36.1
(Mar-May) (3.4) (8.9)
Summer 30.1 34.2
(Jun-Aug) (1.1) (8.3)
Fall 26.7 35.7
(Sep-Nov) (2.3) (10.3)
Winter 22.4 27.7
(Dec-Feb) (0.6) (5.22.6-35.1
(Dec-Feb) (0.6) (5.1)
Table 3-5. Formulae for converting between straight-line and curved carapace measurements of
Kemp's ridley turtles, Lepidochelys kempii. TSCL=total straight-line carapace length,
SSCL=standard straight-line carapace length, MSCL=minimum straight-line carapace
length, and MCCL=minimum curved carapace length.
1.01 SSCL- 0.0199
1.02 MSCL + 0.157
0.958 MCCL + 0.676
0.989 TSCL + 0.0469
1.01 MSCL + 0.176
0.948 MCCL + 0.687
0.977 TSCL 0.113
0.929 SCCL + 0.408
0.937 MCCL + 0.511
1.04 TSCL- 0.511
1.05 SSCL- 0.562
1.06 MSCL- 0.386
Table 3-6. Mean annual growth rates of Kemp's ridley turtles, Lepidochelys kempii, by capture
interval, netting season, and size class (standard deviations given in parentheses).
Turtles were assigned to size classes by mean of initial and recapture SSCL.
Mean SSCL Range of
growth rate growth rates
Data treatments n (cm/yr) (cm/yr)
All recaptures 21 4.21 0.0 8.92
Recaptures > 90 d 8 3.34 1.25 6.47
Recaptures > 180 d 3 3.38 2.78 4.09
Within season 18 4.34 0.0 8.92
Between season 3 3.38 2.78 4.09
20 30 cm 12 3.42 0.0 8.26
30- 40 cm 8 5.50 1.25 8.92
40 50 cm 1 3.25 3.3
Table 3-7. Estimated values of asymptotic length (a) and intrinsic growth rate (k) from nonlinear
regression of von Bertanlanffy growth interval equation for Kemp's ridley turtles,
Lepidochelys kempii, captured in Deadman Bay between 1997 and 1999. One
asymptotic standard error in parentheses.
Data treatment n a k
All recaptures 21 230.8 cm 0.0180 cm
Residual mean square error = 0.3588
All recaptures > 8 206.5 cm 0.0198 cm
90 days (499.9) (0.0567)
Residual mean square error = 0.6428
All recaptures > 3 -784.2 cm -0.00417 cm
180 days (13383.2) (0.0682)
Residual mean square error = 0.7817
20 40 60 80 100
30 35 40 45 50 55 60
65 70 75
20 25 30 35 40
1 Deadman Bay
I I Apalachee Bay
45 50 55 60 65
SSCL N-T (cm)
Figure 3-1. Length-frequency distributions for loggerhead, Caretta caretta, green, Chelonia
mydas, and Kemp's ridley turtles, Lepidochelys kempii, captured in Apalachee and
Deadman bays from 1995 to 1999. Note difference in scales of both axes.
- 'I ,
s, "y ,-i
E 'I" r KEY
.. i .
r ..- .
Figure 3-2. Example of fibropapillomatosis exhibited by a green turtle, Chelonia mydas, from Deadman Bay.
Figure 3-3. Photograph of biofouling by the sea turtle barnacle Chelonobia testudinaria on a #681 inconel flipper tag of a recaptured
Kemp's ridley turtle, Lepidochelys kempii, after 55 days at large.
x = 40.1 cm SCL
sd = 11.7
20 30 40 50 60 71
x = 44.4 cm SCL
sd = 8.5
20 30 40 50 60 71
x = 32.7 cm SCL
sd = 7.3
n = 63
20 30 40 50 60 71
x= 33.1 cm SCL
sd = 6.2
20 30 40 50 60 70
Carapace length (cm)
Figure 3-4. Annual relative size composition of Kemp's ridley turtles, Lepidochelys kempii,
captured in Deadman Bay from 1996 to 1999.
Figure 3-5. Kyphotic green turtle, Chelonia mydas, captured in Deadman Bay.
Based on CPUE, it may appear that set-netting was an effective method for
capturing Kemp's ridley turtles. Difficulties utilizing CPUE data to make comparisons
are often left unaddressed and have led to the suggestion by the Turtle Expert Working
Group (TEWG, 1998) to standardize CPUE to aid in making statistically defensible
comparisons through space and time. Intuitively this makes sense. For example, CPUE
data generated from unequal effort between years and netting locations in this study show
a decline in CPUE with an increase in effort (Table 3-1). However, standardization
would also require all in-water studies to use the same gear, and the same effort
regardless of local conditions. This highly impractical approach would thereby preclude
the use of most, if not all, of the data from this study, as well as other highly productive
fishery independent in-water studies, based purely on methodology (e.g. Witzell and
Schmid 2004). TEWG has subsequently suggested that trawl surveys may be the only
reliable source of data for analysis of long term trends (TEWG 2000). The results of a
mixed method, including trawls, fishery dependent study of marine turtles of
Apalachicola-Apalachee Bay showed that all Kemp's ridley turtles < 25 cm SSCL were
captured in less than 1 m depth (Rudloe et al 1991). If a trawl-only survey was
implemented in the area, not only would a significant component of the size frequency
distribution be lost, thereby skewing the apparent size and age structure, but much of the
bay would be inaccessible to the sampling gear. Insights into marine turtle habitats and
areas of abundance, age and size distributions, temporal and spatial migratory patterns,
sex ratios, and growth rate can be achieved without the use of CPUE as the primary
Though data collected in Apalachee Bay were limited, data generated by marine
turtle captures in Deadman Bay demonstrated the importance of the area as a critical
developmental habitat. While the presence of marine turtles was known in the nearshore
waters of the Big Bend region of the eastern Gulf of Mexico, Deadman Bay was
previously unrecognized as an area of marine turtle concentration (Caldwell and Carr
1957, Carr and Caldwell 1956, Rudloe et al 1991, Schmid 1998, True 1887). Prior to this
study, research in the region was focused west of the St. Marks River and south of
Suwannee Sound. Similar to these areas, Deadman Bay is located in the largest
remaining seagrass bed in North America, although at the local scale each embayment is
quit different (CSA 1985). Schmid (1998) suggested habitat and prey partitioning within
his study site resulted in differences in marine turtle species composition between the two
capture locations within Waccasassa Bay. No such obvious habitat choices are possible
in the rather homogenous Deadman Bay. The larger Kemp's ridleys of Waccasassa Bay
preferred hard bottom habitat and all observations of the smaller ridleys of Deadman Bay
were made over seagrass beds (Schmid and Barichivich 2005, Schmid et al 2003). The
size distribution of Kemp's ridleys from Deadman Bay is very similar to that of the upper
Texas and Louisiana coast, but once again the habitats are quite different (Landry et al
2005). The beachfront habitats from their western Gulf of Mexico study are most like the
preferred ridley habitat of Waccasassa Bay.
The large proportion (11.5, 35.7, and 27.2%) of post pelagic Kemp's ridley (20-25
cm SSCL), green (< 40 cm SSCL) and loggerhead (< 50 cm SSCL) turtles support the
hypothesis that this area may be an ejection point for marine turtles recruiting from the
pelagia to the benthos (Collard and Ogren 1990). Additionally, the observation of small
loggerhead turtles (23.7, 33.5 and 49.6 cm SSCL) suggests these individuals did not enter
the North Atlantic Gyre before recruiting to a demersal habitat. A possible alternative
ontogenetic migration route for loggerhead turtles may lie within the Gulf of Mexico.
Historically, Kemp's ridleys in this region were not known to migrate to other areas
to overwinter. Few ridleys marked on the Florida west coast have been recovered
elsewhere, but one notable record was a movement from Homosassa Florida to the
Chesapeake Bay (Lutcavage and Musick 1985). A pattern of southerly migration has
been described for Kemp's ridleys inhabiting the nearshore waters of the Northwest
Atlantic (Henwood and Ogren 1987, Morreale and Standora 2005, Schmid 1995).
Despite the evidence for seasonal movements in the Atlantic, no such pattern can be
confirmed for the eastern Gulf of Mexico. Interestingly, the former Florida west coast
commercial fishery operated from April until October (the first cold weather of the year).
This and other fishery independent studies in the region have failed to capture marine
turtles in water less than 200C. Commercial marine turtle fishermen suggested to Carr
and Caldwell (1956) that at least a portion of the green and Kemp's ridley turtles in the
Crystal River-Withlacoochee area brumated rather than migrated to warmer water, citing
observations of some individuals captured in the early part of the season coming "up out
of the mud" (Carr 1995). Although overwintering behavior has been demonstrated for
loggerhead turtles in the Cape Canaveral ship channel, it has yet to be verified in Kemp's
ridleys (Carr et al 1980). Recent satellite telemetry of six Kemp's ridleys captured and
released in Waccasassa Bay demonstrated an offshore and southerly migratory pattern,
thereby confirming at least some segment of the local population of ridleys leaves the
area during the coldest months of the year. Telemetered turtles left the area in late
November and returned in March. Their departure, and perhaps return, seems to have
coincided with a change in sea surface temperature (Schmid and Witzell, in press).
While these dates are in agreement with months not represented by historic fishing effort
in the area, Kemp's ridleys were captured in Deadman Bay late into December. The
possibility that these late season observations were turtles passing through while
migrating to other locales seems unlikely, since several individuals were local residents
that had been captured earlier in the year. Additionally this population of smaller turtles
would have to begin their migration earlier in the year than individuals from the Cedar
Keys, since they likely travel slower and are initially further north (Schmid and
Barichivich 2005). It cannot be ruled out that those individuals observed in Deadman
Bay did not migrate, and may represent a non-migratory component of the local
population. A similar year-round occurrence of Kemp's ridley turtles has been observed
in the Apalachicola and Apalachee estuarine area (Rudloe et al. 1991).
In foraging grounds south of Deadman Bay, some marked marine turtles were
subsequently recaptured at the point of initial capture. Both Kemp's ridley and green
turtles returned to the Crystal River-Withlacoochee fishing grounds after being marked
and released in the Cedar Keys. Two of 25 (8%) Kemp's ridleys marked and released in
the Cedar Keys returned to their feeding grounds some 40 km away before being
recaptured after 43 and no less than 91 days (Carr and Caldwell 1956). Likewise, 9.4%
of the ridleys marked at Corrigan Reef were subsequently recaptured at the same location
14 to 839 days later (Schmid 1998). The recapture rate for Deadman Bay was similar
(11.5%), although the turtles were not recaptured at the same location but in the same
vicinity. Additionally, half the ridleys recaptured, including all three individuals
recaptured multiple times, had been held in captivity for fecal sample collection and
returned to the bay within 48 hours. Even this added disruption to a species known to be
"unstable and irascible" did not deter these individuals from remaining in the area (Carr
1942). Though the proportion of multi-annual to within-season recaptures from the area
is low, the seasonal fidelity of immature Kemp's ridleys cannot be overstated.
An issue which impacts both growth and recapture analyses is tag retention. There
was a slightly lower rate of tag loss observed in Deadman than the 35% seen in
Waccasassa Bay, but the intercapture durations were very different. Although the total
number of recaptures was similar between studies, there were nearly equal numbers of
recaptures within and between seasons in Waccasassa, whereas 85.6% of recaptures in
Deadman Bay occurred within a given season (Schmid 1998). If the recapture intervals
in Deadman Bay were of greater duration, like Wacassassa Bay, the tag loss rate would
likely increase and may be similar to those reported by Schmid (1998). In both studies,
tag loss seems directly attributable to biofouling, mostly by barnacles. In response to
their observations, Schmid and Ogren (1992) tested plastic Jumbo-Roto tags (Dalton
Supplies Ltd.) as an alternative to #681 inconel. Each turtle received one inconel and one
plastic tag. It had been suggested the smooth radius of the plastic post would be less
likely to sever the trailing edge of the turtle's flipper, especially with the added resistance
and sharp cutting edge created by barnacle growth, than the bare edge of the punched
sheet steel used for the #681 (Bjomdal and Bolten, unpubl.). In addition to barnacles,
coral growth has been reported on flipper tags of turtles captured in Cape Canaveral. A
stainless steel alloy containing copper, like monel, though less corrosion resistant than
inconel which lacks copper, may be a better choice for flipper tags given its inherent
resistance to biofouling (Schmid and Ogren 1992).
Temporal and Geographic Shift in Size
Based on observations of the former Crystal River-Withlacoochee commercial
fishery, Carr and Caldwell (1956) suggested larger Kemp's ridleys were captured early in
the April to November commercial season. Neither the results of their analysis of
commercial landings nor those of this study could statistically support seasonal shifts in
size class (Carr and Caldwell 1956). However, the mean SSCL of ridleys varied
seasonally in Waccasassa Bay; turtles captured in summer were significantly larger than
those captured in fall (Schmid 1998). In contrast, a fishery-dependent survey of
Apalachicola-Apalachee Bays found the mean size of Kemp's ridleys also varied with
season, but larger turtles were captured in the winter months, December through
February. These results were likely biased by the increase in trawl effort coincident with
the shrimp season and an increase in survey depth (Rudloe et al. 1991). This suggests an
offshore migration can not be ruled out (Ogren 1989).
No difference in annual size distribution was shown for Kemp's ridley turtles
captured in Deadman Bay over the four years of survey. A similar comparison of 10
years of data from Waccasassa Bay resulted in at least one anomalous year, 1991. Two
possible explanations for the shift in size class were cited; an influx of pelagic
Sargassum, and the introduction of new gear, a smaller mesh net (Schmid 1998). While a
change in Gulf currents with an associated influx of Sargassum, and presumably
accompanying commensals (e.g. small turtles), may be a plausible explanation, the effect
of gear could not be ruled out. During surveys in Deadman and Gullivan bays, small
turtles (<30cm SSCL) were observed escaping through 25.0 and 20.5 cm mesh tangle
nets, respectively (Witzell and Schmid 2004). Consequently the nets used in Deadman
Bay were replaced by a 10 cm mesh size. An analysis of the relationship between
capture methods utilized in Deadman Bay and the mean SSCL of the Kemp's ridleys
captured there demonstrated a bias toward larger size classes with larger mesh sizes. The
extent of the effect of gear bias cannot be determined, but to date no other published
study of Kemp's ridley turtles has used nets with this small a mesh size. It would appear
simple to recommend switching to smaller mesh nets, but the ability to tangle turtles
while preventing the smallest size classes from escaping is a difficult balance to achieve.
If mesh sizes become too small not only will larger turtles bounce off the net rather than
tangle, but bycatch and subsequent net repair may increase. In the case of Deadman Bay,
the benign nature of the area allowed the use of the encirclement net as a blockade as
well as a tangle net. The clear shallow waters allowed for the recovery of turtles, tangled
or not, by a snorkeler. In many locations, such as Gullivan Bay, biotic and abiotic
conditions (e.g. strong currents, dark water, sharp limestone and oysters, marine
mammals and large sharks) precluded the use of anything other than an entanglement
strike net. Ultimately the solution may require testing gear and accounting for associated
bias or using multiple sampling methods to best suit the objectives of a long term study.
A comparison of published growth rates of Kemps' ridleys captured along the west
coast of Florida shows a north to south trend of increasing growth rate in nearly every
category of interval, season, and size class with greater than one observation. This trend
is complemented by a decreasing difference between within-season and between-season
growth (Schmid 1998, Witzell and Schmid 2004). This latitudinal gradient may be
associated with a shorter, or complete lack of, migration or torpor in the southwestern
corner of state. Alternatively, this may be an artifact of seasonal resource availability in
the temperate waters of the northern peninsula versus those of subtropical southwest
Florida. The greatest rate of growth by size class was different for each study and
showed no trend, suggesting each location may best suit the nutritional requirements of
various classes differentially. Although differences in diet may be responsible for
differences in growth rate, growth may also be affected by food availability,
environmental quality, and temperature (Morreale and Standora 2005).
Length-based estimates of growth for all recaptures from Long Island Sound, Cape
Canaveral, and Sabine/Calcasieu passes show no clear geographic pattern when
compared to those from the Florida gulf coast. The reported growth rate of Kemp's
ridleys recaptured in Long Island Sound (4.1 cm/yr) is most similar to that observed in
Deadman Bay (4.21 cm/yr, Table 3-6) as is the size range (27-39 cm SSCL) of the turtles
upon which the estimates are based. Despite an activity period of less than 4 months per
year, Kemp's ridleys in northern developmental habitats appear to exhibit comparable
growth rates to ridleys from the northeastern Gulf of Mexico, where they are active at
least three-quarters of the year (Morreale and Standora 2005).
There appears to be a pattern of decreasing occurrence of headstarted Kemp's
ridley turtles from Apalachee Bay clockwise around the Florida Gulf coast. During the
1995 netting season of this study, 60% of the ridleys captured in Apalachee Bay were
positively identified as headstarts, whereas only one or two individuals were observed in
each of the following sites, (0.83%, 1 of 121) Deadman Bay, (0.78%, 2 of 254)
Waccasassa Bay, and possibly (0.52%, maybe 1 of 192) Gullivan Bay (Schmid 1998,
Witzell and Schmid 2004). The pattern is possibly a function of distance between the
release and capture locations. Two of the three turtles captured in Apalachee Bay were
released off Panama City, the nearest headstart release point to the study area. In
addition, a temporal shift may be occurring. Of 106 Kemp's ridley turtles captured in
surveys from 1984 to 1988 in the Apalachicola-Apalachee bays, no headstarted turtles
were identified (Rudloe et al 1991). Seven years later, most of the turtles captured in the
Apalachee Bay were headstarts.
One headstarted Kemp's ridley was captured in Deadman Bay. This 1986 year
class turtle was the only adult Kemp's ridley observed in the area during this study. A
female, she could not be further identified due to loss of all individual marks. No
readable PIT tag could be found in either fore-flipper, although a living tag in her
carapace was obvious, as was a tag scar in the right fore-flipper. Records of adult
Kemp's ridleys along the Florida west coast are rare, especially since the end of the
commercial fishery. Beginning in May 1989 Kemp's ridleys began nesting on both
coasts of Florida (Meylan et al. 1990). Since then, 21 incidences of nesting, or attempted
nesting, scattered through eight counties, including two in the panhandle, have been
documented through the 2005 nesting season (FWRI 2006). While none of these nesting
females could be positively identified as headstarts, those origins could not be ruled out
(Johnson et al. 1999). Bowen et al. (1994) saw this marked increase in aberrant nesting
11 to 14 years (the presumed time to maturation) post initiation of the headstart program
as "strikingly coincidental" (Schmid and Witzell 1997, Zug et al. 1997). While an
argument can be made that nesting by Kemp's ridleys has always occurred in Florida, it
seems very unlikely this species conspicuous habit of nesting during the day would have
gone unnoticed (Johnson et al. 1999). Additionally, the natal origin of this species was so
uncertain, largely due to the absence of any nesting or reproductive observations prior to
1960, it had earned the name "bastard" turtle because it was thought to be a hybrid
between a loggerhead, hawksbill, and perhaps a green turtle (Carr 1942, 1952). Early
investigations would have surely turned up reports of nesting had it ever been observed in
the state. A similar observation of an adult, 65.2cm SSCL, female Kemp's ridley was
made in Gullivan Bay. Though not specifically cited as such in publication, Schmid
(pers. com.) is confident she was a headstart turtle. A size frequency outlier, she was
marked only by a flipper tag scar, but no readable PIT or living tag (Witzell and Schmid
2004). The inability to confirm the origin of this suspected headstart turtle captured in
Gullivan Bay is one example of the many vagaries of this often criticized NMFS program
(Huff 1989, Woody 1991, Frazer 1992, Hewavisenthi 1993). Only 9.6% of the 8,026
individuals released in the first six years of the program had living tags, and they were
not applied to all turtles until 1990. Until 1988, no more than 5.6% of any year class was
PIT tagged, with an overall application rate of 27.5% of the first 22,576 headstarts
released. The greatest tagging rate (98.3%) of any of the methods was flipper tags. As
previously discussed, flipper tags are quickly lost and not suitable for long-term
reidentification, assuming retention rates similar to those of tags applied to wild turtles.
Further, gross errors in describing headstart marking techniques confound their
identification. For example, publications on the identification of headstart living tags use
scute and bone nomenclature interchangeably, and frequencies of PIT tags applied to
headstarts are incorrectly stated and could lead to the use of the wrong equipment to
attempt to read them (Fontaine and Shaver 2005, Caillouet et al. 1986). The use of coded
wire tags should also be noted. Beginning in 1984, they were applied to the right or left
flipper of all headstarted turtles. We were fortunate to have the rather esoteric and
expensive equipment required to read wire tags, but could not detect these tags in any of
the four headstarts captured in this study. Had the tag been readable, no information
other than the presence of the tag could be gained without surgical removal.
Currently the state's only industrial river, the Fenholloway, is located
approximately 40 km north of Deadman Bay. It has been estimated that effluent from the
Buckeye Florida L.P. Kraft mill in Perry has resulted in the loss of 25 km2 of seagrass
beds near the river mouth. While the direct impact on marine turtles is unknown, the real
danger may lie in the sublethal effects of the consumption, and subsequent
biomagnification, of contaminated crabs and other prey. Plans to mitigate discharge into
the river have focused on a pipeline intended to bypass the river and pump effluent
directly into the Gulf of Mexico. Another potential source of pollution, a coal fired
powerplant meant to supply distant municipalities, is intended to be built on the same
river. Though the atmospheric deposition of mercury into local terrestrial, freshwater,
and marine foodwebs is certain, the impacts of powerplant intakes and coal delivery
barges and associated structures in the shallow waters of the area are not. While coastal
development of the "Forgotten Coast" is very low, it is increasing and will lead to more
boats on the water. Presently the area is enormously popular during the summer months
for the recreational scallop harvest. Though reports of marine turtle standings in the area
are low, this may not be a true reflection of the number of deaths, but the result of little
effort and the low-energy vegetated shoreline. Current statistics from the Florida Sea
Turtle Stranding and Salvage Network show that approximate 50% of ridleys and 33% of
the loggerheads stranded in Dixie and Taylor counties are related to boat impacts (Alan
Foley, pers. com.).
Tagging should continue in the area, but focused research should be directed at
behavioral studies addressing the effects of increased boating activity and seasonal
migrations. Further characterization of specific habitats and how turtles are using them
seasonally and annually should be emphasized. Toxicological research should be
considered to address the potential risks from pulp mill and coal powerplant in
conjunction with a trophic study to elucidate contaminant pathways
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William James "Jamie" Barichivich was born in Fort Monmouth, New Jersey, on
May 21, 1970. He grew up in Sarasota, Florida, spending much of his time fishing in the
bays and Gulf of Mexico between Tampa Bay and Charlotte Harbor. He graduated from
Sarasota High in 1988 and received an Associate of Arts degree from Manatee
Community College. He began pursuing a degree in architecture at the University of
Florida in 1991 but changed majors to wildlife ecology and conservation in his second
year. His background as a waterman secured him a job with a generous PhD student, Jeff
Schmid, aiding in the capture and telemetry of Kemp's ridley sea turtles near the Cedar
Keys, Florida. He worked three field seasons on that project and graduated with a
Bachelor of Science in forest resources and conservation in the spring of 1996.
After graduation, he began working for the United States Geological Survey
(USGS) on the development of a capture/recapture study of marine turtles in the Florida
Big Bend. This work soon evolved into Jamie's thesis research when he began graduate
study in the Department of Wildlife Ecology and Conservation.
Jamie has continued to work for the USGS as his research interests have expanded.
Since 2000 he has studied amphibians as part of the Department of Interior Amphibian
Research and Monitoring Initiative, working across the Southeastern United States. He
has also worked on other USGS projects, including mitigation of vertebrate road
mortality, Gulf Sturgeon population census, and trophodynamics of deep sea benthic