Title Page
 Executive summary
 Table of Contents
 Report of the Steering Committ...
 Part I. Committee and working...
 Part II. Abstracts of particip...
 Part III. Appendices

Group Title: Technical paper - Florida Sea Grant College Program ; no. 53
Title: Fishery recruitment in Florida waters
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00076600/00001
 Material Information
Title: Fishery recruitment in Florida waters toward a predictive capability ; report of a workshop held February 15-17, 1989, Live Oak, Florida
Series Title: Florida Sea Grant Technical Paper
Physical Description: v, 60 p. : ; 28 cm.
Language: English
Creator: Kleppel, G. S ( Gary S )
Seaman, William, 1945-
American Fisheries Society -- Florida Chapter
Florida Sea Grant College
Publisher: Florida Sea Grant College Program, University of Florida
Place of Publication: Gainesville FL
Publication Date: 1989
Subject: Marine fishes -- Growth -- Florida   ( lcsh )
Fishery management -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
Bibliography: Includes bibliographical references.
Statement of Responsibility: edited by G.S. Kleppel, William Seaman, Jr.
General Note: "September 1989."
General Note: "Project No. IR-89-2 ; Grant No. NA86AA-D-SGO68."
General Note: "Sponsored by Florida Sea Grant College Program, Florida Chapter of the American Fisheries Society."
Funding: This collection includes items related to Florida’s environments, ecosystems, and species. It includes the subcollections of Florida Cooperative Fish and Wildlife Research Unit project documents, the Florida Sea Grant technical series, the Florida Geological Survey series, the Howard T. Odum Center for Wetland technical reports, and other entities devoted to the study and preservation of Florida's natural resources.
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Bibliographic ID: UF00076600
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
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Resource Identifier: oclc - 25097387

Table of Contents
    Title Page
        Title Page
    Executive summary
        Unnumbered ( 4 )
    Table of Contents
        Table of Contents 1
        Table of Contents 2
    Report of the Steering Committee
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
    Part I. Committee and working group reports
        Page 12
        Report of the Working Group on Open-Ocean pelagic fisheries
            Page 13
            Page 14
            Page 15
            Page 16
            Page 17
            Page 18
            Page 19
            Page 20
        Report of the Working Group on coastal pelagic fisheries
            Page 21
            Page 22
        Report of the Working Group on reef and benthic fisheries
            Page 23
            Page 24
            Page 25
            Page 26
            Page 27
            Page 28
        Report of the Working Group on estuarine fisheries
            Page 29
            Page 30
            Page 31
            Page 32
    Part II. Abstracts of participants
        Page 33
        Page 34
        Page 35
        Page 36
        Page 37
        Page 38
        Page 39
        Page 40
        Page 41
        Page 42
        Page 43
        Page 44
        Page 45
        Page 46
        Page 47
        Page 48
        Page 49
        Page 50
        Page 51
        Page 52
    Part III. Appendices
        Page 53
        Page 54
        Page 55
        Page 56
        Page 57
        Page 58
        Page 59
Full Text
FLSGP-W-89-002 C2

Technical Paper No. 57


Toward a Predictive Capability

G.S. Kleppel

and William

Seaman, Jr.


COurLr PaRoona
Research, education, and extension for responsible marine resource use


Toward a Predictive Capability

Report of a Workshop
Held February 15-17, 1989
Live Oak, Florida

Edited by

G.S. Keppel
Nova University Oceanographic Center
8000 North Ocean Drive
Dania, FL 33004

William Seaman, Jr.
Florida Sea Grant College Program
University of Florida
Gainesville, FL 32611

Sponsored by
Florida Sea Grant College Program
Florida Chapter of the American Fisheries Society

Steering Committee
J. Bohnsack, M.E. Clarke, G.S. Keppel, J. Napp,
R. Nelson, W. Seaman, Jr.

Project No. IR-89-2
Grant No. NA86AA-D-SGO68
Florida Sea Grant Technical Paper 57
September 1989
Price $2.00


Organizing, conducting and reporting on a workshop is a
large, difficult and frequently frustrating task. In the end,
hopefully, the benefits are worth the effort. Workshops general-
ly do not highlight the talents of individuals and few of those
who contribute are adequately recognized. Many of those who work
the hardest never even see their names in print. The editors of
this volume wish to express to those who contributed, often well
beyond their level of compensation, our personal thanks and our
belief that what you have helped to accomplish will ultimately
benefit science and society.

We are grateful to all of the scientists and managers who
participated in the workshop, and especially to those who later
did the report writing. We thank Ken Haddad and his staff at the
Florida Marine Research Institute (Department of Natural Re-
sources) and the Florida Chapter of the American Fisheries Socie-
ty for their efforts in organizing and conducting the workshop.
Dr. James Cato of the Florida Sea Grant College Program provided
support, staff and considerable motivation for this undertaking.
Marilyn Little and Jay Humphreys of the Sea Grant office provided
valuable administrative and editorial assistance. Kathy Maxson
of the Nova University Oceanographic Center did much of the
typing and most of the art work. Denis Frazel, also of Nova,
contributed his time to organizing and preparing the final
product. Finally, we thank the Steering Committee who spent many
hours designing the conceptual framework upon which this workshop
was built.

G.S. Kleppel
William Seaman, Jr.

Fishery Recruitment in Florida Waters:
Toward a Predictive Capability

Executive Summary

Marine fisheries in Florida encompass 109 finfishes and
invertebrate species, reflecting the state's diversity of coastal
and ocean habitats. Management of Florida's valuable fisheries
necessarily entails forecasting fluctuations in fished stocks.
By understanding recruitment, the processes that result in the
survival of fishes from early life history to the adult or ex-
ploited stage, management potential can be improved. Responding
to an interest in recruitment expressed by Florida's academic
scientists, the Florida Sea Grant College Program, in conjunction
with the Florida Chapter of the American Fisheries Society,
organized the workshop at Live Oak to determine the usefulness of
understanding recruitment, the likelihood of success and the
mechanism for proceeding. The workshop elicited national atten-
tion; over 100 scientists and managers attended. The partici-
pants provided the framework for a multidisciplinary, academic-
government research initiative to elucidate the processes con-
trolling survival in certain key state fisheries. Workshop
participants determined which fishes and invertebrates (usually
species but in one case, a family), representative of Florida's
fishery habitats, should be the focus of recruitment research
over the next decade. The fishes (and invertebrates) selected
for further study are economically valuable, typical of certain
geographical regions and biological processes, and generally have
been well studied. Further study of these fishes is likely to
bring significant gains in knowledge and management potential.
In addition, participants identified the information and technol-
ogy improvements that will be necessary for successfully defining
the relationship between fishes, their habitats and the fluid

What follows is a description of the Live Oak workshop's
objectives and results. The document represents the collective
wisdom of many of Florida's leading scientists. It is designed
to provide guidance for strategic planning in future fishery
research and management activities.

Table of Contents


Acknowledgments ........................................

Executive Summary .....................................

Part I. Committee and Working Group Reports

Report of the Steering Committee ........................

Report of the Working Group
on Open-Ocean Pelagic Fisheries.......................

Report of the Working Group
on Coastal Pelagic Fisheries .........................

Report of the Working Group
on Reef and Benthic Fisheries ........................

Report of the Working Group
on Estuarine Fisheries ...............................

Part II. Abstracts of Participants

Are reef fishes fruit trees? -- The marine
wilderness strategy
J. A. Bohnsack .........................................

The Gulf Stream front, its role in larval fish
survival and recruitment in Florida
M. Clarke, J. Napp, G. Kleppel, A. Russo ...............

Aspects of the biology of the Nassau grouper,
Epinephelus striatus
P. L. Colin ............................................

Unifying concepts in recruitment
L. B. Crowder ..........................................

Reduction and shifts in occurrence of larval and
juvenile Sciaenidae in lower St. Johns River,
C. DeMort, J. Murphy ...................................

The importance of early-juvenile habitat to
Florida fishery recruitment
R. E. Edwards ..........................................

Predicting fishery recruitment: Florida, the
southeast, the nation
E. Fritz ...............................................



. 1












Seagrass, mangrove swamp and herbaceous halophyte
marsh fish communities, spatial and trophic
guilds, faunal overlap, population dymanics and
the importance of relative habitat associations
R. Grant Gilmore ....................................... 40

Predation on juvenile spiny lobster: Who's been
eating our lunch?
W. F. Herrnkind, M. J. Butler IV ....................... 41

Estuarine spawning of the red drum in Mosquito
Lagoon on the east coast of Florida
D. R. Johnson, N. A. Funicelli ......................... 42

Cross-shelf distributional ranges of newly
settled Haemulids and Lutjanids (18 species)
among several habitat scales and techniques for
collecting, visual surveying and field/aquaria
K. Lindeman ............................................ 43

Use of otoliths to determine the age and growth
of spotted seatrout
M.J. Maceina ........................................... 45

SEFCAR: The University of Miami's southeastern
Florida and Caribbean recruitment study
M. F. McGowan .......................................... 46

Drum prior to recruitment to the offshore
spawning population
M. D. Murphy, R. G. Taylor ............................ 47

Pro-active management: Will the lights come on
in Florida?
R. Nelson .............................................. 48

Lessons learned from the grunts: Observational
studies of recruitment
J. C. Ogden ............................................ 49

Physical aspects of fishery recruitment
D. B. Olson ............................................ 50

Recruitment analysis program for the Little
Manatee River/Tampa Bay estuary
E. B. Peebles .......................................... 51

Fishery research in Florida: A systematic
approach to a diversity of problems
W. Seaman .............................................. 52

Part III. Appendices

Appendix 1. List of Participants ...................... 53

Appendix 2. workshop Agenda ........................... 58

Report of the Steering Committee

G.S. Kleppel, W. Seaman,Jr.,
J. Bohnsack, M.E. Clarke, J. Napp, R. Nelson

I. Introduction

In this report, we present the rationale, objectives and
some of the results of the Fishery Recruitment workshop from the
perspective of the Steering Committee. As explained below,
workshop participants spent much of their time in small, thematic
working groups which have reported their findings individually,
in the papers that follow. In this paper we attempt to merge the
concepts and ideas offered by the working groups, emphasizing
those ideas that were recurrent. We believe that these key con-
cepts provide a framework around which a state recruitment
research initiative can be developed.

Recruitment is the set of processes that results in the
survival of organisms to a certain stage in the life cycle. In
the context of fisheries, the terminal stage of recruitment is
often considered that at which reproduction or economic exploita-
tion occurs. It can be argued that if one understands the proc-
esses that facilitate survival among a population of
organisms, then one should be able to estimate the proportion of
that population that will survive to a given stage. As a result,
one might better predict changes in the population over time.
And, if the population is exploited (fished), one could, poten-
tially, manage the human impact on it. Developing the ability to
predict stock dynamics is a major goal of fishery science.
Achievement of that goal may depend, in part, on our understand-
ing of recruitment.

In spring 1988, a group of scientists, identified by Florida
Sea Grant as sharing an interest in recruitment, met in Miami to
discuss the motivation for a research initiative addressing the
problem of recruitment in some of Florida's fisheries. In re-
sponse to increasing, but mostly independent, activity in this
field, a multidisciplinary dialogue was proposed in the form of a
workshop to further identify scientists involved in recruitment
research, to prioritize the research objectives of a statewide
recruitment initiative and to relate these objectives to the
goals identified in Florida Sea Grant's long-range plan (1988).
The meeting at Live Oak in February 1989 was organized for these

II. Workshop Rationale

In contrast to many areas of the country where only a few
fishes or invertebrates are exploited, over 100 marine and estua-
rine species are fished in Florida (FMFC 1986). Management of
marine fisheries in Florida is complicated by this diversity of

exploited species, and by the variety of habitats and life histo-
ry strategies of these species.

Workshop participants considered the need, feasibility, and
strategy for studying recruitment in the context of boosting the
potential for management of Florida's marine and estuarine fish-
eries. The workshop objectives were to:

1. identify key or representative species for which an
understanding of recruitment might be feasible within the next

2. identify the interactions between the biology of fishes
(and invertebrates), and physical properties and processes in the
environment that are pertinent to recruitment and tractable

3. determine the major gaps in our understanding of the
processes that contribute to recruitment in general and for key
species in particular,

4. consider the unifying principles around which processes
that result in recruitment can be described,

5. define the roles of Florida's diverse scientific commu-
mity in studying recruitment, especially potential pathways for
collaboration and cooperation between scientists from academe and
State and Federal facilities.

III. Workshop Organization

A. General Structure

The workshop was divided into three components: formal
scientific presentations, thematic working groups, and plenary
discussion sessions (see Agenda, Appendix 2). Scientific pre-
sentations opened the meeting to help define the scope of the
problem and to identify the interests of the workshop partici-
pants. The remainder of the time was devoted to small working
group meetings, intermingled with plenary discussion sessions.

There were four working groups, of 12-20 participants, and
designated on the basis of major fisheries: Open-Ocean Pelagic;
Coastal Pelagic; Reef/Benthic; and Estuarine. The choice of
these groups was based on the types of environments that are
exploited in the state's fisheries. It was recognized, however,
that fishes frequently utilize more than one habitat during their
life cycles. Thus, while the working groups were named for the
habitats where the adults are fished, discussions of the species
comprising each fishery were not limited to any single habitat.
In fact, certain species were considered important by more than
one working group.

B. Working Group Obiectives

Through review and discussion of existing fishery informa-
tion, each working group sought to identify: the important or key
species (see below) in the adult fishery; the characteristics of
the environment that are important to that fishery; and, the data
and technology needed to demonstrate progress in our understand-
ing of the fishery.

1. Key species -- The criteria for establishing the priority
of species (i.e., deciding which fish species are important) were
determined within the working groups. Among the major weighting
factors were: value of the fishery; potential for significant
progress in understanding its recruitment (or population dynam-
ics) within the coming decade; fishing pressure on the stock; how
well the species represented a certain life-history strategy.

2. Environment -- There is growing recognition that biologi-
cal and physical hydrodynamic process are intimately coupled
(Legendre and Demers 1984; Bratkovich 1988). As such, hydrody-
namics represent a driving force in ecosystems (Haury and Pieper
1988) and may influence fish population dynamics in a variety of
ways and at all life-history stages (Lasker 1981; Mearns 1988;
Svejkovsky 1988). Among the goals of the workshop was to promote
an increase in the awareness, discussion and study of physical-
biological interactions that may affect fish recruitment. This
emphasis was apparent in the opening session (D. Olson this
volume). It is critical for the scientific community to know the
extent to which the links between the recruitment of "key spe-
cies" and the fluid dynamic environment can be and need to be
resolved in order to obtain predictability and management capa-

3. Data needs and technical limitations -- The workshop was
designed to draw attention to gaps in the data base that limit
our understanding of recruitment and to shortcomings in technolo-
gy and methodology that limit sampling efficiency and the estima-
tion of population sizes. Emphasis was placed on identifying
tractable problems and upon developing multidisciplinary ap-
proaches to solving them. A second focus was on gear development
and on the recognition that the understanding of fish population
dynamics is limited by sampling efficiency.

IV. Results of the Workshop

Although the working groups represented a diversity of
specialties, interests and scientific orientations, certain
recurrent themes and messages seemed to be projected. We present
below, a summary of these themes from the perspective of the
Steering Committee. The perspectives of the working groups can
be gained from their detailed, individual reports.

The workshop results are divided into three components:
scientific observations; approach; and, consensus. The first
component, scientific observations, deals with three topics: key
species, environmental attributes and technology. Working group
discussions of these topics focused on existing and needed data
for understanding recruitment. This section represents our
perception of the major elements of the working group

The component on approach addresses certain procedural and
conceptual issues of a recruitment research initiative. The
final component, consensus, deals with the question of whether
recruitment is an important issue from the standpoint of the
Florida's scientific community. The discussion focuses on our
interpretation of the higher than expected attendance and broader
than expected regional interest in the workshop.

A. Scientific observations

1. Key species -- With few exceptions, the organisms selected
as key or representative species are commercially or recreation-
ally exploited, rather than simply abundant (Table 1). The
working groups tended to include some fishes as target species
because significant progress in understanding their seems feasi-
ble within the next decade.

2. Environment -- It was apparent that data are needed on
many of the biological variables classically associated with
recruitment (Table 2). These include habitat, predator/prey
interactions, competition, movement patterns, biogeography and
community structure. It was also recognized that interactions
between organisms and hydrodynamic processes or phenomena, such
as occur through advection or at fronts, may have enormous sig-
nificance on survival of early life history stages and ultimately
upon recruitment (Table 3).

Another theme expressed by the working groups was the need
to understand low frequency variability through long term data
acquisition (Table 3). It was noted that ocean-atmosphere cou-
pling on a variety of time/space scales can influence recruit-
ment. There are few systematic evaluations of long term environ-
mental variability, especially with respect to fish recruitment.

Finally, all of the working groups made reference to the
need to identify and understand human impacts on recruitment.
The focus of the working groups varied from assessment of fishing
pressure to understanding the impact of habitat modification. It
was pointed out that the anthropogenic impact on fish population
dynamics is often not resolveable from natural variability given
the current data.

3. Technology -- A final recurrent theme was sampling. The
need to develop gear and techniques that permit quantitative
sampling of all life history stages and habitats is critical, and
at present, not available for most fisheries. One of the clear-

Table 1. Key* species of fishes and invertebrates (scientific names are
given in each working group report) identified by working groups as most
suitable for future recruitment research.

Reason(s) for choice as priority species**

Habitat Species 1 2 3 4 5 6 7 8






Black Mullet


King Mackerel

Spanish Mackerel

Black Sea Bass

Vermillion Snapper

Gag Grouper

Spiny Lobster

Red Porgy


Red Snapper

Not given***

----H -H- + -I-I

+ + -H- + -H-

+ + ++ + -H-

++ +

-f-I +

++ +

++ +

++ +

*One group preferred the term "representative" instead of key.

**Reasons for choosing a species:
1. Economically valuable; 2. strong data base/high probability of
progress; 3. representative of physical processes) or physical-
biological interaction; 4. representative of geographic region;
5. representative of life history strategy; 6. easy to sample
(throughout life cycle)/in culture; 7. abundant at one or more
ontogenetic stages; 8. other.

Rating: ++ strong reason for choosing
+ weak reason for choosing

blank -- not a reason

***The working group considered the establishing priorities inappropriate
at this time (see Estuarine Working Group Report).

+ -++

+ + +

+ +

+ +

Table 2. Biological factors and processes considered important
by working groups to recruitment of key fish and invertebrate
species in Florida waters.


Open Pelagic

Coastal Pelagic



movement between habitats
life history/biology representative of a
common biological process or inter-
action with environment

predator/ prey interactions
early larval stages
sources and size of mortality

planktonic dispersal
community structure
predator/ prey interactions

spawning dynamics
developmental bottlenecks
predator/prey interactions
habitat structure and utilization


Table 3. Physical characteristics of marine environments that may
affect recruitment.

Habitat Characteristics

Open Pelagic

Coastal Pelagic



fronts and associated dynamics
advection (vertical and horizontal)
and associated forcing functions
low frequency events

advection/ transport
ocean-atmosphere coupling at many scales
fronts and other aggregating mechanisms

transport at scales affecting larval
low frequency events that influence
bottom topography

hydrological & climatic regimes
physical habitat processes and structures

est messages of this workshop was that gear development and
sampling methodology need to be given priority in future research
agendas. Quantitative sampling of fishes throughout their life
histories, in numerous habitats, and on a variety of time scales
is an important objective, upon which the success of the recruit-
ment research initiative will depend.

B. Approach

In developing a scientific program focused on understanding
fishery recruitment, several operational priorities emerged.
These concern political boundaries, multidisciplinary interac-
tions, and unifying concepts.

1. Political boundaries -- States must take a regional or
larger focus, as fish stocks are often migratory and definitely
not confined by state boundaries. An intermural, cooperative ap-
proach was evident at the workshop through attendance by scien-
tists from state and federal institutions in Georgia, North
Carolina, Tennessee, and Michigan. It is proposed that an inter-
state dialogue be established throughout the Southeast to begin
development of a regional approach to fishery management.

2. Multidisciplinary approach -- There was a strong appreci-
ation among the workshop participants for the intimate associa-
tion between the organism and its environment. Understanding
that association will improve the ability of researchers to
describe the characteristics of "the survivors,"those fishes that

Recruitment is affected by the biotic and the physical
environments, and studies of these processes must be undertaken
in an integrated, multidisciplinary fashion. The workshop de-
rived much of its strength from the interactions that developed
between physical oceanographers and fisheries biologists, and
between practitioners of various subdisciplines of biology.

3. Unifying concepts -- Florida exploits 109 species of
marine fishes and invertebrates (FMFC 1986). It is impractical
to believe that management of all of these species is possible
within the decade. What is possible is that certain general
categories of organisms can be identified based on common life
history or other attributes (Miller et al. in press; Crowder this
document) It is normal for scientists to seek general principles
that govern processes. Whether we work from the specific to the
general, or vice versa, it will nonetheless be critical to have
certain operational models at our disposal.

It was, however, difficult to come to terms with the concept
of unifying principles. At this point the idea apparently re-
quires further refinement. However, most participants seemed to
favor the effort to seek generalizations, so long as the impor-
tance of the species is not lost. Clearly, generalization re-
quires a strong data base on individual species. Resistance to
the unifying concept idea may reflect weakness in the data base.

C. Consensus

Among the most important messages of the Live Oak workshop
was that the community views recruitment as an important area for
study. The expected participation of the workshop was between 30
and 50 individuals. While the official registration of the
meeting was about 60, the actual attendance of the opening ses-
sion was much higher (we believe over 100). There is no doubt
that recruitment is an important topic in the scientific communi-
ty at all levels (academic, government, private). The attendance
of the meeting, the diversity of disciplines represented, and the
geographical range of the participants indicates that serious
consideration needs to be given to fishery recruitment at the
program development levels of Florida's government.

V. Toward a Recruitment Research Initiative

The Live Oak workshop provided a clear consensus that a
state research effort in recruitment is in the best interest of
Florida and has local, regional and national support. This
scientific consensus is based on the beliefs that:

1. Management of fisheries depends in part on an under-
standing or predictability of stock fluctuations;

2. Understanding the processes that lead to recruitment
will enhance understanding of the causes of stock fluctuations
and, hence, the development of fishery management;

3. A predictive understanding of certain critical aspects
of recruitment seems feasible within the next decade for some

A recruitment research initiative within Florida can be
perceived to have three components: Research; Development;
Education. The program's structure must foster collaboration
between government and academe, and among the scientific
disciplines. A committee of academic and government scientists
might ultimately be responsible for program development and
oversight. While the nature of this program would necessarily be
long-term (there are 109 species to ultimately manage), progress
toward specific goals would be measurable by the achievement of
discrete tasks. Ultimately, the unifying concepts approach will
be feasible and the implications of the recruitment program will
extend beyond Florida's borders.

Collaboration with regional and federal projects and promo-
tion of the Florida program within and beyond the state will be
an important component of the committee's activities. This will
help to reduce the cost of the program within the state, and
increase the rate of data base development.

VI. What is Gained -- the Ultimate Goal

American fisheries are conservatively valued at about $15
billion annually. However, these fisheries are highly suscepti-
ble to economic disaster from natural processes that are recog-
nized but not predictable (e.g., el Nino), anthrogenic activi-
ties, and as yet poorly understood natural variability in the
environment and in fish stocks. The American public has support-
ed the effort to manage fisheries and avoid economic disasters by
improving the scientific understanding of fishes and the process-
es that govern their production. Continued public support re-
quires that the scientific community demonstrate some level of
success in the ability to predict fish stock fluctuations. The
Live Oak meeting resulted in a consensus that we are close to
that end for certain species. It is this groundswell of interest
at the level of the scientific community which suggests that a
commitment to recruitment research is presently appropriate.
Much hard work is still ahead. However, it would appear that
significant progress is feasible.

VII. References

Bratkovich, A. 1988. The use of planktonic organism
distribution as an indicator of physical variability in
marine environments, pp. 13-34. In, Soule, D.F. and G.S.
Kleppel (eds.), Marine organisms as indicators. Springer-
Verlag, New York.

Crowder, L. 1989. Unifying concepts in recruitment. In,
Kleppel, G.S. and W. Seaman, Jr. (eds.), Rep. Workshop
on Fishery Recruitment in Florida Waters. Florida
Sea Grant College, Gainesville.

Florida Marine Fisheries Commission (FMFC). 1986. A matrix of
fisheries information needs: Florida's renewable marine
resources. University of Miami.

Florida Sea Grant College Program. 1988. Long-range plan, 1989-
1993. Univ. Florida, Gainesville. 20pp.

Haury, L.R. and R.E. Pieper. 1988. Zooplankton: Scales of
biological and physical events, pp. 35-72. In, Soule, D.F.
and G.S. Kleppel (eds.), Marine organisms as indicators.
Springer-Verlag, New York.

Lasker, R. 1981. The role of a stable ocean in larval fish
survival and subsequent recruitment, pp. 80-89. In,
Lasker, R. (ed.), Marine fish larvae: Morphology, ecology
and relatio to fisheries. Washington Sea Grant, Seattle.

Legendre, L. and S. Demers. 1984. Towards dynamic biological
oceanography and limnology. Can. J. Fish. Aquat. Sci. 41:

Mearns, A.J. 1988. The "odd fish": Unusual occurrence of marine

life as indicators of changing ocean conditions, pp. 137-
176. In, Soule, D.F. and G.S. Kleppel (eds.), Marine
organisms as indicators. Springer-Verlag, New York.

Miller, T.J., L.B. Crowder and J.A. Rice. In press. Larval
size and recruitment mechanisms in fishes: Toward a
conceptual framework. Can. J. Fish. Aquat. Sci.

Olson, D. 1989. Physical aspects of fishery recruitment.
In, Kleppel, G.S. and W. Seaman, Jr. (eds.), Rep.
Workshop on Fishery Recruitment in Florida Waters. Florida
Sea Grant College, Gainesville.

Svejkovsky, J. 1988. Remotely sensed ocean features and their
relation to fish distributions, 177-197. In, Soule, D.F.
and G.S. Kleppel (eds.) Marine organisms as indicators.
Springer-Verlag, New York.

Part I. Committee and Working Group Reports


Report of the Working Group on
Open-Ocean Pelagic Fisheries

L. Barthouse, A. Bratkovich, M. Clarke, W. Conley
L. Crowder, D. Frazel, E. Fritz, D. Hoss, D. Kendall,
S. Killey, G. Kleppel, M. Murphy, J. Napp**, D. Olson
P. Ortner*, J. Silberman, R. Taylor

* Chair
** Rapporteur

I. Introduction

Each working group at the Recruitment Workshop was charged
with identifying the major biological and physical processes
associated with time varying recruitment of fishes in specific
habitats. In particular we were asked to to identify those
processes which:(1) are relevant to specific life history stages
of many fishes; (2)are amenable to further study; and (3) have
the potential of eventually yielding predictive models i.e.,
fisheries forecasts (potential harvest).

We focused our initial discussion on the general phenomenon
of physically-induced, temporal fluctuations in populations of
fishes and decided that "representative" rather than "key" spe-
cies would be more useful. Our strategy was to consider how one
might study such problems without regard to regional jurisdiction
or local/state economic interests since many fishes cross state
boundaries during their lifetimes. We quickly came to an agree-
ment that among the most suitable species for study there were
two generic life history strategies: (1) the transgressivee" I
species which are common inhabitants of oceanic, coastal and
estuarine waters throughout the Gulf and South Atlantic coasts;
and (2) species that appear to be associated with coastal/pelagic
frontal systems. We also felt that the focus of a successful
program should be towards obtaining a general, process-oriented
understanding of natural variability in fish populations rather
than toward an immediate prediction of next year's catch from
this year's catch or spawn. This approach is advantageous be-
cause it is prerequisite to discriminating changes related to
anthropogenic stresses (overfishing, pollution, habitat destruc-
tion) from natural variability of fish stocks(i.e., internally
regulated or induced by climatic variation and/or global changes,
for example, in circulation pattern or water mass characteris-

1 Transgressive species are those that spawn in coastal or
oceanic waters, but whose juveniles are dependent upon estuarine
nursery areas.

II.Tractability of Research Problems Addressed with
"Representative Species"

Coordinated biological-physical programs are notoriously
expensive. To sustain national and regional moment and work
within projected, available funds, it is crucial that a tractable
problem be identified and addressed before pursuing problems that
are less amenable to scientific study. It is also critical that
the information obtained be relevant to as many species or spe-
cies types as is possible. Five criteria were suggested to
evaluate the suitability of specific fisheries-recruitment prob-
lems for a pilot study.

1. The species of choice must exhibit time varying recruit-

2. The species of choice should have a relatively short
life span or reach sexual maturity in a short time period.

3. The life history stages of the chosen species should be
both identifiable and abundant in standard sample collections.

4. There should be a definite spatial separation between at
least two of the important life history stages.

5. An historical data base should exist for the pertinent
aspects of the chosen species' life history and the physical
environment in which it lives.

The first criterion is a given; it is pointless to study how
variable biological and physical processes interact to affect
recruitment if the stocks are invariant. A short life span or
time to sexual maturity (1-3 years)is essential to maximize the
number of recruitment cycles studied within the life span of a
typical field program i.e., one should have the opportunity to
test and modify mechanistic models more than once. Although some
species (e.g., mackerels) that are not commonly collected during
sampling of early life history stages have enormous economic
importance as adults, the scientific task of understanding re-
cruitment will be easier if the population size can be accurately
assessed for all life history stages. In fact, if certain life
history stages are difficult to sample (e.g., juvenile stage),
then it will be essential to develop new, adequate samplers and
sampling strategies to assess their abundance. Ontogenetic
separation of stages is advantageous in at least two regards:
one, cannibalism is relatively less important as a source of
mortality for the pre-recruits and two, at least one physical
mechanism advectionn) is likely to play an important role in
determining recruitment variability. The existence of a substan-
tial biological and physical data base will permit a research
program to formulate hypotheses at the outset and the analysis
objectives can then be pursued in parallel with field observa-
tions. A long-term data set would permit hindcast analysis and
model corroboration as well as facilitate the link to long-term
climate change effects.

III. Specific Recommendations and Considerations

A. Null Hypothesis

As a modus operandi we suggest adopting the following
strawmann" hypothesis:

H : Recruits to a population are chosen at random from the
field of propagules.

H : Recruits to a population are not drawn randomly from the
field of propagules.

The utility of this approach is that upon rejection of the
null hypothesis it directs effort toward identification of exact-
ly which non-randomly selected set of propogules, which discrete
reproductive "event", was differentially successful. These
conceptual steps lead to the critical, subsequent step of identi-
fying the reasons) why those individuals survived to recruit to
the population i.e., what were the common biological and physi-
cal factors that determined survivorship?

One method suited to this type of question is otolith analy-
sis for birthdate distribution (e.g., Brothers 1975; Methot 1983;
Rice et al. 1987). In practice, the birthdate distribution of a
population is determined several times during the recruitment
process. If the birthdate frequency distribution of the survi-
vors to a particular stage is the same as the spawning date
distribution (which also has to be determined), then the null
hypothesis cannot be rejected. If, on the other hand, the birth-
date distribution of the recruits is distinct from the distribu-
tion of reproductive effort, then the recruits were not drawn at
random from the field of propagules, and one can go on to identi-
fy the commonalities among the survivors. Otolith analysis also
provides the mean and variance of growth rates of individual
fishes and can potentially provide growth rate trajectories from
ring spacing patterns. We recognize at least two inherent diffi-
culties with this type of analysis: it doesn't directly address
the contribution of egg mortality to recruitment variability and
its rigor depends upon the degree to which one can samplethe same
population (cohort) over time throughout its range.

B. Potential Life History Strategies and Species for Study

We considered examples of "representative" species types
mentioned earlier: transgressive species and pelagic/coastal,
front-related species. Transgressive species are those whose
adults spawn offshore but whose juveniles are found inshore,
often in estuarine nurseries. Front-related species are those
whose larvae or juveniles may be found in particularly high
abundances in association with coastal/pelagic fronts (e.g., the
western edge of the Gulf Stream). Potential species include:
Transgressive black (striped) mullet (Muqil cephalus), Atlantic
menhaden, Gulf menhaden (Brevoortia tyrannus and B. patronss,

spot (Loeiostomus xanthurus), croaker (Micropogonias undulatus),
grey snapper (Lutianus griseus), and flounder (Paralichthys sp.).
Front-related dolphin (Corphyaena hippurus), swordfish (Xiphias
qtladius), king mackerel and Spanish mackerel (Scomberomorus
cavalla and S. maculatus) and blue fin tuna (Thunnus thynnus).
Although the majority of larval fish in oceanic waters belong
to the families Myctophidae, Gonostomidae, and Sternoptychidae
(Ahlstrom 1965; Loeb 1980; Richards 1984), the life history of
these animals preclude their.successful recruitment into Florida
waters. Further, although there are several active fisheries for
myctophids in other parts of the world because there is no exist-
ing local fishery for any species of these families, we have
little knowledge of the degree to which their annual recruitment
is variable. Last, because of their exclusively pelagic life
style, these fishes are less likely to exhibit annual variations
in recruitment than transgressive or front-related species.

C. Specific Representative Species

Based on the above criteria, two transgressive and one
pelagic/coastal front-related species seemed to offer the most
advantages. Black mullet and menhaden were chosen as representa-
tive transgressive species and the dolphin fish was chosen as a
representative pelagic/coastal, front-related species. Dolphin
fish, however, fulfilled fewer of the above criteria, than either
of the transgressive species.

Black mullet, abundant on the west coast of Florida, leave
their estuarine habitats and migrate offshore (to the shelf edge)
to spawn. This offshore migration may be correllated with the
passage of low pressure systems (Mahoudi et al. 1989). Cross
shelf transport of larvae may also be dependent upon storm-
induced shelf exchange processes (for discussion of physical
response see Hseuh et al. 1982). An appropriate question for
this population would be whether recruitment is event-driven
(e.g., only during the largest or strongest storms) and varies as
a function of spawning distance from the estuary (which may
relate to large scale physics, such as the shoreward excursions
of the Gulf Loop Current). This fishery accounted for 20% of the
tonnage of finfish landed in Florida in 1986-87 and has been
biomass dominant for two decades. Although the literature is
limited (Arnold and Thompson 1958) researchers in Florida's
Department of Natural Resources have been studying the growth,
life history and reproductive biology of black mullet for some
time (Mahoudi et al. 1989) and have recently developed otolith
techniques that provide daily growth for both larvae and juve-
niles (Conley, personal communication).

Atlantic and Gulf menhaden spawn in coastal waters in the
fall and winter, and after hatching many larvae are transported
across the shelf and into estuarine nursery areas. In both the
Atlantic Ocean and Gulf of Mexico wind driven currents and storm
events are important in the transport of menhaden larvae (Nelson
et al. 1977; Miller et al. 1984; Checkley et al. 1988). In the
Atlantic Ocean, variability in the speed and direction of the

Gulf Stream may also play an important role in defining the
spawning area, and intrusions of Gulf Stream water may facilitate
transport of larvae across the shelf (Pietraffesa and Janowitz
1988). Intrusions (meanders and eddies) of Gulf Stream water may
cause upwelling of nutrient rich water in their wakes (Atkinson
1985) stimulating both primary and secondary productivity (Yoder
1983; 1985; Paffenhofer 1985) which produces food for the menha-
den. In the north central Gulf of Mexico, Gulf menhaden larvae
may be mostly dependent on wind events for their transport, while
in the northwestern Gulf both wind events and the relative posi-
tion of the Gulf Loop Current may be important (Shaw et al.
1985a; 1985b; 1988).

The existing biological data base for both Gulf and Atlantic
menhaden is more extensive than for any other east or Gulf coast
fishery. Data exist on: the distribution, morphology, growth,
behavior and feeding of various life history stages (Reintjes
1969; Fore 1970; Hoss and Blaxter 1982; Govoni et al. 1983; Hoss
and Phonlor 1984; Powell and Phonlor 1986; Sogard et al. 1987;
Govoni 1989) and on the reproduction of adults (Higham and Nich-
olson 1964). Culturing is now routine (Hettler 1981) and otolith
aging has been documented (Simoneaux and Warlen 1987; Warlen
1988). While commercially important in their own right, it is
equally important that black mullet and menhaden are important
forage fish for other, larger, and more individually valuable in
both sport and commercial fisheries.

Little is known about dolphin fish by comparison to menha-
den, but they are one of the most studied pelagic, front-related
species. The adults spawn in blue water following a lunar perio-
dicity and both larvae and juveniles are commonly found in asso-
ciation with flotsam and sargassum in the Gulf Stream front.
Dolphin reach maturity in only 1-2 years, and can be cultured
(Beardsley 1967; Hassler 1975; 1977). The degree to which popu-
lation recruitment is dependent upon frontal features and whether
this dependence relates to feeding or perhaps refuge from preda-
tion is unknown, but these factors are thought to be important.
The dolphin fish fishery is not currently managed, but the Na-
tional Marine Fisheries Service predicts that it will have to be
managed within the next 5 years (Hoss, personal communication).
Physical data relating to the Gulf Stream front are extensive and
the dynamics of the system is the subject of current oceanograph-
ic research programs within the academic community.

IV. References

Arnold, E.L. and J.R. Thompson. 1958. Offshore spawning of the
striped mullet, Muqil cephalus, in the Gulf of Mexico.
Copeia 1958: 130-132.

Atkinson, L.P. 1985. Hydrography and nutrients of the south-
eastern U.S. continental shelf, p. 77-92. In L.P. Atkinson,
D.W. Menzel, and K. A. Bush (ed.), Oceanography of the
southeastern U.S. continental shelf. Amer. Geophys. Union.

Beardsley, G.L., Jr. 1967. Age, growth, and reproduction of the
dolphin, Coryphaena hipppurus, in the Straits of Florida.
Copeia 1967: 441-451.

Brothers, E.B., C.P. Mathews and R. Lasker. 1975. Daily growth
increments in otoliths from larval and adult fishes. Fish.
Bull. 74: 1-8.

Checkley, D.M., Jr., S. Raman, G.L. Maillet and K.L. Mason.
1988. Winter storm effects on the spawning and larval drift
of a pelagic fish. Nature. 335: 346-348.

Fore, P.P. 1970. Oceanic distribution of the eggs and larvae of
the gulf menhaden. U.S. Fish. Wildl. Serv., Circ. 341.

Govoni, J.J., D.E. Hoss and A.J. Chester. 1983. Comparative
feeding of three species of larval fishes in the northern
Gulf of Mexico: Brevoortia patrons, Leiostomus xanthurus,
and Micropogonias undulatus. Mar. Ecol. Prog. Ser. Vol. 13:

Hagwood, R.W. and G.N. Rothwell. 1979. Sea Grant interim report
1979. Aquaculture in tropical ocean-Coryphaena Sp.
Oceanic Institute, Waimanalo, Hawaii.

Hassler, W.W. and W.T. Hogarth. 1977. The growth and culture of
dolphin, Coryphaena hippurus, in North Carolina. Aquacul-
ture 12: 115-122.

Hassler, W.W. and R.P. Rainville. 1975. Techniques for hatching
and rearing dolphin, Coryphaena hippurus, through larval and
juvenile stages. Univ. North Carolina Sea Grant Program
Publ. UNC SG 75-31. 17 pp.

Hattler, W.F. 1981. Spawning and rearing Atlantic menhaden.
Prog. Fish. Cult. 43: 80-84.

Higham, Joseph R., and William R. Nicholson. 1964. Sexual
maturation and spawning of Atlantic menhaden. Fish. Bull.
63: 255-271.

Hoss, D.E. and J.H.S. Blaxter. 1982. Development and function
of the swim bladder-inner ear-lateral line system in the
Atlantic menhaden, Brevoortia tyrannus (Latrobe). J. Fish.
Biol. 20: 131-142.

Hoss, D.E. and G. Phonlor. 1984. Field and laboratory observa-
tions on diurnal swim bladder inflation-deflation in larvae
of gulf menhaden, Brevoortia patrons. Fish. Bull., 82:

Hseuh, Ya, G.O. Marmorino and L.L. Vansant. 1982. Numerical
model studies of the winter-storm response of the west
Florida shelf. Jour. Phys. Ocean. 12: 1037-1050.

Mahoudi, et al. 1989. Black mullet population assessment: 1987-
1988 annual report to MARFIN. pp. 53. Florida Department
of Natural Resources.

Methot, R.D., Jr. 1983. Seasonal variation in the survival of
larval Engraulis mordax estimated from the age distribution
of juveniles. Fish. Bull. 81: 741-750.

Miller, J.M., J.P. Reed and L.J. Pietrafesa. 1984. Patterns,
mechanisms and approaches to the study of migration of
estuarine-dependent fish larvae and juveniles. In Mecha-
nisms of migrations in fishes, pp. 209-225. J.B. McCleave,
G.P. Arnold, J.J. Dodson and W.H. Neill (eds.). Plenum, New
York. 574 pp.

Nelson, W.R. M.C. Ingham and W.E. Schaaf. 1977. Larval transport
and year-class strength of Atlantic menhaden, Brevoortia
tyrannus. Fish. Bull. 75: 23-41.

Paffenhofer, G.A. 1985. The abundance and distribution of zoo-
plankton of the southeastern shelf of the U.S., pp. 104-
117. In Atkinson, D.W. Menzel, and K. A. Bush (eds), Ocean-
ography of the southeastern U.S. continental shelf. Amer.
Geophys. Union.

Pietrafesa, L.J., and G.S. Janowitz. 1988. Physical oceano-
graphic processes affecting larval transport around and
through North Carolina inlets. Am. Fish. Soc. Symp. 3:34-

Reintjes, J.W. 1969. Synopsis of biological data on the Atlantic
menhaden, Brevoortia tyrannus. U.S. Fish. Wildl. Serv.
Circ. 320. 30 pp.

Rice, J.A. L.B. Crowder and M.E. Haley. 1987. Exploration of
mechanisms regulating larval survival in Lake Michigan
bloater: A recruitment analysis based on characteristics of
individual larvae. Trans. Amer. Fish. Soc. 116: 703-718.

Shaw, R.F., B.D. Roger, J.H. Cowan, Jr. and W.H. Herke. 1988.
Ocean-estuary coupling of ichthyoplankton and nekton in the
northern Gulf of Mexico. Am. Fish. Soc. Symp. 3: 77-89.

Shaw, R.F., J.H. Cowan and T.L. Tillman. 1985a. Distributions
and density of Brevoortia patrons (gulf menhaden) eggs and
larvae in the continental shelf waters of western Louisiana.
Bull. Mar. Sci. 36: 96-103.

Shaw, R.F., W.J. Wiseman, R.E. Turner, L.R. Rouse and R.E. Con-
drey. 1985b. Transport of larval gulf menhaden Brevoortia
patrons in continental shelf waters of western Louisiana: a
hypothesis. Tans. Am. Fish. Soc. 114: 452-460.

Simoneaut, L.F. and S.M. Warlen. 1987. Occurrence of daily
growth increments in otoliths of juvenile Atlantic menhaden,
pp. 443-451. In R.C. Summerfelt and G.E. Hall (eds). Age
and growth of fish. Iowa State Press, Ames. Iowa.

Sogard, S., D.E. Hoss and J.J. Govoni. 1987. Density and depth
distribution of larval fishes at three locations in the
northern Gulf of Mexico. Fish. Bull. 85: 601-609.

Warlen, Stanley M. 1988. Age and growth of larval gulf menha-
den, Brevoortia patrons, in the northern Gulf of Mexico.
Fish. Bull. 86: 77-90.

Yoder, J.A. 1983. Statistical analysis of the distribution of
fish eggs and larvae on the southeastern U.S. continental
shelf with comments on oceanographic progress that may
affect larval survival. Estuar. Coast. Shelf Sci. 17: 637-

Yoder, J.A. 1985. Environmental control of phytoplankton pro-
duction on the southeastern U.S. continental shelf, pp. 93-
103. In Atkinson, D.W. Menzel, and K. A. Bush (eds),
Oceanography of the southeastern U.S. continental shelf.
Amer. Geophys. Union.

Report of the Working Group on
Coastal Pelagic Fisheries

S. Andree, P. Christian, J. Finucane, C. Grimes*,
K. Haddad, P. Hood, J. Isley, S. Kennedy
B. Mahmoudi, B. Muller, L. Timme, L. Trent


I. Introduction: Key Species

Coastal pelagic species include, but are not limited to,
king, Spanish and cero mackerel, dolphin, bluefish, menhaden and
a group of clupeid and carangid species often referred to as
coastal herrings. Our discussions concentrated on the king and
spanish mackerels, in part, because of the regional importance of
these species. For example, commercial catches of king mackerel
in the Gulf of Mexico are approximately 2000 metric tons annually
with a market value of about $5 million. Recreational landings
are approximately 700 metric tons/year. While there is presently
considerable scientific interest in the mackerel fisheries, we
believe that the research questions, data requirements and sam-
pling problems are generally applicable to most coastal pelagic

II. Recruitment and Fish Stock Dynamics

Four forces act upon fish populations to determine stock
size. These are growth and recruitment, which tend to increase
stock size, and natural and fishing mortality, which act to
decrease the fishable population. The "equation of fishing",
i.e., that the rate of fishing determines the catch, underlies
population dynamic models used to predict the effects of differ-
ent levels and strategies of fishing. While estimates of growth
and natural and fishing mortality have been made, estimates of
recruitment have proved to be intractable.

Recruitment, the process by which eggs are spawned, fishes
hatch, survive and grow to a harvestable size, can and usually
does, vary by orders of magnitude. Inadequate understanding of
the factors that regulate recruitment, and the inability to
predict recruitment, represent major obstacles to the development
of population dynamics models that accurately simulate fishing
effects and predict future stock sizes and yields.

We perceive two component objectives in recruitment re-
search: (1) The ability to predict entry into the fishery; and
(2) understanding year class variability and its causes. The
first of these usually involves sampling to estimate juvenile
abundance, then establishing the reliability of the estimate as a

predictor of recruitment to the fishery. This process is intend-
ed to provide managers with estimates of new recruits which can
be used in stock assessments to adjust harvest levels. The
process, however, does not provide a means to identify the causal
mechanisms that determine year class strength.

The consensus of the working group was that three factors
contribute to the largest extent to the success or failure of a
year class: (1) feeding success, (2) predation, and (3) trans-
port. Physical variability in the ocean (ranging from major
ocean climate events, such as el Nino, to small scale phenomena,
such as local wind events, fronts and upwelling) has important
consequences for all three factors (Legendre and Demers 1984).
These coupled oceanographic-meteorological phenomena influence
early life history stages of coastal pelagic fishes in a variety
of ways (cf. Lasker 1981).

III. Issues for Research

It was the consensus of the working group that the recruit-
ment of coastal pelagic species reflects the impact of both
trophodynamic and environmental processes upon the organism
during the early larval period. It follows that research must
focus on evaluation of the association between young fishes and
potential aggregating and survival enhancement features or mecha-
nisms (e.g., fronts). Efforts must be made to describe and
understand the spatial and temporal variability in larval growth
and mortality associated with predator and prey densities and
with environmental forcing functions.

Lastly, it is important to point out that a major need in
future research is for the ability to sample all size and age
classes in coastal pelagic fisheries. Presently, no reliable
means exists for representative sampling of the large larvae and
juveniles of many coastal pelagic species. Innovative use of
traditional gears (e.g., small mesh gill nets; small mesh purse
seines) and creative development of new sampling methods (e.g.,
high speed trawls) provide fertile ground for future technologi-
cal development.

IV. References

Lasker, R. 1981. The role of a stable ocean in larval fish
survival and subsequent recruitment, pp. 80-87. In, Lask-
er, R. (ed.), Marine fish larvae. Morphology, ecology and
relation to fisheries. University of Washington Sea Grant,

Legendre, L. and S. Demers. 1984. Towards dynamic biological
oceanography and limnology. Can. J. Fish. Aquat. Sci. 41:2-

Report of the Working Group on
Reef and Benthic Fisheries

J. Bohnsack*, A. Brown, M. Collins, J. Halusky,
D. Harper, B. Herrnkind, R. Holhberg, M. Hulsbeck,
J. Kimmel, D. McClellan, M. McGowan, J. Ogden,
B. Seaman, D. Sutherland


I. Introduction

The reef resources task group met on 16 and 17 February to
discuss reef resource recruitment in Florida waters. This report
summarizes the collective group opinion on various aspects of
recruitment. Although recruitment can be defined in many ways,
the group used the term in the general sense as the resupply of
organisms into a population. The task group concluded that in-
creased attention should be directed at recruitment phenomena.

II. Results

A. Reef Fauna Characteristics

General characteristics of fauna from reefs and hard bottom
areas include planktonic dispersal of eggs or larvae, occupation
of a series of different habitats for different life history
stages, and populations that undergo cyclic fluctuations of
abundance. Most harvested species are characterized by a suite of
life history traits that include long life, slow growth, large
size, low natural mortality during demersal phases, and iteropar-

Reef habitats are widely distributed and important in
Florida. Local ecological conditions are different and large
enough to justify dividing the state into three to five regions
for the purpose of recruitment studies. The major regions sug-
gested include northeast Florida, osuthern Florida, and northwest

B. Targeted Species Research Efforts

A preliminary listing of possible target species for poten-
tial research was assembled by region. Suggestions were black sea
bass (Centropristis striata), vermillion snapper (Rhomboplites
arorubens), and red porgy (Paqrus paqrus) for northeastern Flori-
da; grunts (Haemulidae) and spiny lobster (Panulirus arqus) for
southern Florida; and gag grouper (Mycteroperca microlepis) and
red snapper (Lutianus campechanus) for northwestern Florida.

These targeted species were selected based on their economic
value, known information, widespread distribution in reef habi-
tat, regional abundance, and their potential to be appropriately
tractable for answering questions about interactions between
oceanography and population dynamics. Most species were selected
as possible recruitment models primarily because they could
provide information for predictive fishery purposes that would be
applicable to a suite of species. Grunts were suggested because
of their wide distribution and tractability to sampling, the
short larval duration, and their potential usefulness for theo-
retically oriented studies. Also they are diverse, easily sam-
pled, and apparently not overfished in Florida. Gag grouper were
selected in part because much of the life history is known and
prejuveniles are accessible to monitoring during ingress and
egress from estuaries. Also, they are subject to coastal front
conditions, current transport, and are potentially topographical-
ly constrained by gyres.

Although the group picked target species for study, they
emphasized the simultaneous need and importance of research on
reef habitat, the reef ecosystem, and reef species complexes. The
task team noted the danger in targeting only certain species for
study. Examining specific species without monitoring competitors,
predators, other fish species, food resources, and habitat quali-
ty may be doomed to failure. For example, plankton predators may
limit recruitment via the "wall of mouths" hypothesis. Could
jellyfish abundance determine jack recruitment success?

Long term monitoring was concluded to be important for the
ultimate understanding of the cause and effect relationships of
recruitment variability. Research should be a mix of long term
and short term studies. Some studies could have rapid payoffs in
terms of management advice, e.g. an index of juvenile gag grouper
during their estuarine resident phase could predict recruitment
to the reef fishery one or two years later.

Knowledge of planktonic duration was recognized as important
for defining scales relevant to individual species and physical

Priority for study should be given to species most likely to
be impacted by coastal modifications and human impacts (i.e.
lobster are affected by siltation, mosquito spray, habitat alter-
ation, fishing mortality, coastal development, etc.).

III. Specific Research Considerations

The task group concluded that prioritizing goals was impossi-
ble because of variations in funding, research difficulty, varia-
tions in proposal strength, unpredictable local research opportu-
nities and differences in researcher capabilities and resources.
The task team did make specific recommendations to guide recruit-
ment research efforts and funding which are listed below:

1. Emphasis should be placed on key questions that are
broadly applicable to several species.

2. Increased basic information is needed on life history
parameters and natural history for specific species.

3. Length of larval life needs to be determined for given
species and regions to set appropriate time scales for further

4. Ontogenic information is needed for taxonomic identifica-
tion purposes for many species, especially for larvae.

5. Museum collections were recognized as important sources
of data that needed additional support.

6. Better descriptions were needed involving physical ocean-
ographic transport mechanisms with emphasis on the Loop Current,
cross shelf transport, the Florida Current, Charleston Bump Gyre,

7. Behavioral studies are important to explain actual dis-
tributions which often differ from passive transport trajecto-

8. Recruitment sources and sinks needed to be better identi-

9. The effects of fisheries on the spawning stock biomass
needs greater attention with regard to the supply of larval
recruits and fecundity.

10. Genetic studies are needed for better stock identifica-

11. Many of the recruitment problems were recognized to be
international in scope because of widespread distributions and
long distance transport capabilities among species. Progress and
resolution of these problems requires greater international
cooperation, coordination, and investigation.

12. Research and monitoring should emphasize hypothesis
testing rather than blind data collection.

13. Links need to be defined between habitat and occurrence
and shelter and food availability.

14. Available databases should be searched for environmental
correllations with abundance cycles.

15. To make progress on recruitment problems, many grants
will need to be larger and for longer terms than the one or two
year grants currently favored.

16. Research should be directed at distinguishing between
human and naturally induced recruitment variability.

17. Research should determine whether successful recruits
are random survivors or a definable cohort subset.

IV. Worksheets

The task group drafted study sample worksheets for some
target species that were intended to be representative but not
exclusive of possible research targets.

SPECIES: Lutjanidae (snappers)
REGION: All Florida


GENERAL: Important, common, locally abundant, settlement
habitats vulnerable to human coastal disturbances.


1. Determine larval duration, age and growth of early
2. Determine survival during pre-settlement transport
3. Describe functional relationships between settlement and
distribution and quality of juvenile habitat.
4. Determine survival rates in secondary (pre-adult) habi-
5. Describe taxonomy for larvae less than 15 mm.
6. Determine spawning locations and behavior.

SPECIES: Panulirus (lobsters)
REGION: Southern Florida (Pan-Caribbean)



1. Economically important.
2. Subject to impacts from human coastal modifications.
3. Abundant populations.
4. Much information already available.


1. Distribution, population structure, movements, and
reproductive patterns of adults and late juvenilesare well known
in Florida.
2. Considerable information is available on newly settled
and algal dwelling stages.
3. Temporal patterns of inshore invasion by postlarvae and
their entry into Florida Bay via channels between islands from
the the Atlantic side of the Keys is well documented.


1. Determine distribution and dispersal processes of post-
larvae in Florida Bay. This includes information on current flow
patterns, length of postlarval life, behavior, algal habitat,
distribution, and sources of mortality.
2. Determine source regions for Florida stocks. Seek inter-
national cooperation for potential upstream sampling of parental
3. Determine ecology, distribution, and abundance of juve-
nile stages between algal-phase and about 50 mm carapace length.
Emphasize habitat needs and sources of mortality at these stages.
4. Develop and test predictive models of fishable stocks
based on settlement patterns, mortality estimates, and juvenile
habitat extent and condition.
5. Promote research on usable methods of identification of
oceanic phyllosomas (electrophoresis, mitochondrial DNA, meris-
tics, etc.).
6. Determine oceanic transport mechanisms and local behav-
iors that regulate larval recruitment importance to Florida. This
includes current studies, and rates and depths of vertical migra-
tion at specific larval stages. (Australia has used this ap-
7. Determine advactive processes and transport from the
Florida Current into the reefs.
8. Validate methods of measuring postlarval settlement into
Florida Bay and subsequent movements and distribution.

Report of the Working Group on
Estuarine Fisheries

G. Bailey, J. Bente, R. Bishop, R. Brockmeyer, C. DeMorte
R. Edwards, A.-M. Ecklund, G. Gilmore, D. Johnson,
S. Kennedy, M. Lazari, R. Lewis, K. Lindeman, W. Loftus
R.E. Matheson*, R. Mattson, B. McLaughlin, J. Miller,
M. Mitchell, J. Murphy, R. Nelson, E. Peebles, K. Peters,
R. Ruiz-Carus, D. Scheidt, M. Schirrapa, J. Tilmant

* Chair

I. Introduction

Of the four regions considered in this workshop, estuaries
are perhaps the most complex in terms of factors leading to
recruitment variability in fishes and macro-invertebrates. This
complexity is due to the diversity of species, life history
stategies, and habitats. On the other hand, estuaries are
somewhat more readily sampled from a logistical and economic
point of view (i.e., many of our laboratories are located on
estuaries, and the waters are generally shallow), even though
obtaining quantitative samples in most important habitat types is

The importance of studies of recruitment variability in
estuarine species cannot be overstated due to the great overall
economic importance of many species, coupled with their great
vulnerability to anthropogenic perturbations. We would suggest
the following list of critical areas for future research to be
considered by funding agencies: evaluation of the state of our
knowledge regarding recruitment-related factors in the life
history of Florida's estuarine fishes; generation of long-term
data bases; studies of single species or guilds which concentrate
on description of early life history stages, collection of basic
early life history data, determination of important habitats and
habitat selection mechanisms; ecosystem studies which concentrate
on interacitons among species and system energy flow patterns;
development and evaluation of quantitative, habitat-specific and
species-specific collecting gear. This list is not meant to be
exhaustive, but we feel that it does indicate some of our major
needs for successful management of Florida's estuarine fish and
macro-invertebrate communities. Some of these needs are
considered in more detail below.

II. Research Needs

A. Data Base Evaluation

The first priority for estuarine recruitment research, as
with all research, is the evaluation of what is currently known
about the subject. This effort should include an assessment of
existing literature, data bases, and archival collection re-

sources in order to develop a data matrix indicating the state of
our knowledge regarding recruitment-related factors in the life
history of Florida's estuarine fishes. This information is
relatively cheap to obtain and can save money in the long run by
preventing duplication of effort.

B. Long-term Data Acquisition

An often recognized priority for recruitment research is the
development of long-term data bases. Such work is expensive,
tedious, and requires a dedicated, well-trained staff. Neverthe-
less, it is absolutely essential for our understanding of natural
variability in recruitment and as baseline data for understanding
the effects of various perturbations on estuarine systems. In
order for these studies to be of value, funding agencies must be
willing to commit to long-term funding with the understanding
that maximum benefit of the research will not be realized for at
least several years. Funding agencies should also encourage
managers of long-term studies to make specimens, data, and other
resources available to other researchers whenever possible in
order to derive maximum benefit from funds committed to these

C. Life History Studies

One area of research that could benefit greatly from data
and specimens collected in long-term projects is the general area
of early life history research on estuarine species. Basic data
such as descriptions of egg, larval, and juvenile stages; spawn-
ing location and time; and age and growth of early life history
stages are lacking for many abundant species in Florida estu-
aries. A complete egg-to-adult series has not been described for
many Florida species, and no comprehensive guide exists for the
identification of the early life history stages of Florida fish-
es. Spawning season and location as well as basic age and growth
data are available for some species (especially those of direct
economic importance), but most growth data are at the level of
annual growth and, thus, may miss important early life history
events. Also, almost no attention has been given to geographic
variation in life history patterns within species. This type of
research obviously provides the foundation of basic data upon
which all other recruitment-related research must be based.

D. Fishes in the Environment

1. Physical and chemical -- The effects of physical/chemical
regimes on movement and survival at all life history stages have
rarely been studied in detail for any species. For example,
current and precipitation patterns occurring at critical periods
in the animal's life history can affect locality of settlement
and, thus, amount of suitable habitat available for a given year
class. In other words, if current patterns in a given year carry

larvae of a seagrass-dwelling species into areas with no sea-
grass, recruitment of that year class should be affected. Simi-
larly, heavy rains during the recruitment period of a species
showing strong salinity preferences might either increase or
decrease the amount of available nursery habitat. These rela-
tionships can again be best studied with long-term monitoring of
physical/chemical factors along with population fluctuations
among fishes.

2. Habitats -- Studies to determine critical nursery habi-
tats and the behavioral means for locating these habitats among
estuarine fishes are also of critical importance. Such studies
have generally concentrated on structural habitats, but other
physical/chemical features should also be considered. Further-
more, most studies to date have merely documented habitat utili-
zation as opposed to preference, selection, or behavioral mecha-
nisms for selection. The relevant scales for conducting such
studies also need to be considered. For instance, in a study of
fishes in seagrass habitats, is the relevant scale seeagrass
versus unvegetated substrate or should comparisons be made among
species of seagrass or among sites containing the same species of
seagrass but under different hydrological conditions.

3. Ecological interactions -- Another cause of recruitment
variability that is extremely complex and, therefore, difficult
to quantify is the various levels of interaction among popula-
tions in the estuary. Even if all chemical and physical factors
were held constant, recruitment success of a given species would
still depend on population density of prey and competitors.
Thus, ecosystem-level studies are necessary to clarify food webs
and determine important competitive interrelationships. Such
studies can rapidly expand beyond reason for any funding agency,
and, therefore, the determination of appropriate temporal and
spatial scales for recruitment-related ecosystem studies is a
critical problem. Areas of special concern would be levels of
food availability for early life history stages of species of
interest as well as the determination of bottlnecks in ontogenet-
ic development since these life history stages may have a dispro-
portionate effect on subsequent year class strength.

III. Technology Needs

Much of the above-mentioned research requires adequate means
of quantitatively collecting estuarine fishes in a variety of
habitats. We could fill quite a few pages with descriptions of
sampling gear that has been designed to collect estuarine fishes.
The basic need is to find a sampling gear that gives a true
representation of the fish community in such diverse habitats as
seagrass, mangroves, cordgrass, shellfish beds, seawalls, open
sand to mud bottom, channels, etc. The basic problems are quite
familiar to anyone who has conducted ecological studies in estu-
aries: no gear functions in the same manner in many different
habitats, and no gear functions with the same efficiency for all
fish species. In practice, therefore, strictly quantitative

studies must generally be limited to few habitat types and a
particular species or guild. Ecosystem-level studies must in-
clude multiple gear types, and meaningful comparisons can often
only be made using rank abundance and/or frequency of occurrence.
Development of new habitat-specific and species/guild-specific
gear types for quantitiative, estuarine sampling needs to be an
ongoing process and requires continued funding.

All of the data produced by new gear types and the above-
mentioned studies should be used to generate and test hypotheses
relating to life history bottlenecks for particular species.
Questions generated will deal with population fluctuations at
various life history stages and/or recruitment variability in
relation to various life history strategies or environmental

IV. Anthropogenic Effects

Finally, a critical area for research in Florida estuaries
is the study of the effects of man's activities on recruitment
success. Activities of interest include various types of
construction (e.g., the building of spillways, seawalls,
causeways, marinas, etc., as well as channelization), degredation
of water quality through production of effluents, and changing of
physical/chemical regimes by such activities as regulation of
freshwater flow. Considering the rapid rate of coastal
development in Florida, all of the above-mentioned studies need
to be designed with these anthropogenic influences in mind.

Part II.

Abstracts of Participants

Are reef fishes fruit trees? -- The marine wilderness strategy

James A. Bohnsack, Miami Laboratory, Southeast Fisheries Center,
NOAA Fisheries

Fishery practices that maximize biomass or economic returns
may exploit reef fishes without adequate consideration of in-
terspecific interactions, reef fish life history strategies, and
the evolutionary responses to intraspecific genetic diversity.
Fishing mortality selectively depletes older and larger individu-
als and may have become a major evolutionary selective pressure
for many reef fish species. Reef fishes are characterized by
slow growth, long life, low natural mortality, and iteroparity.
Evolutionary theory predicts that these life history characteris-
tics are selected under conditions of high uncertainty for pre-
reproductive survival and relative stable survival of reproduc-
tives. Fishing mortality is predicted to select for life history
characteristics of short life span, small size, and early repro-
duction. Under intense fishing mortality, some species may face
acute recruitment failure, phenotypic shifts, and loss of in-
traspecific genetic diversity, which could be disastrous to reef
fish fisheries. Permanent marine wildernesses, areas protected
from consumptive exploitation, could provide areas with stable
population age distributions and natural community structure.
Such areas will help protect intraspecific genetic diversity,
maintain ecological balance, and ensure against recruitment
failure. Economic, social, and fishery benefits may exceed
fishery costs.

The Gulf Stream front, its role in larval fish survival and
recruitment in Florida

M.E. Clarke and J.M. Napp, University of Miami, RSMAS/BLR
G.S. KIleppel and A. Russo, Nova University Oceanographic Center

The Gulf Stream is a pervasive mesoscale feature in the
North Atlantic that has a significant impact on the oceanography,
meteorology and biology of this ocean and the adjacent coastal
regions. It is hypothesized that, off southeast Florida, the
recruitment success of many fishes is influenced by the dynamics
of Florida Current cross shelf transport and by the habitat
characteristics of the Gulf Stream front.

A multi-institutional, interdisciplinary program, involving
biological and physical oceanographers will examine, through
coordinated field and laboratory experiments and sampling, the
frontal region of the Florida Current off Broward County. The
program will seek to ascertain: (1) the suitability of the Flori-
da Current shoreward front as a larval fish habitat (relative to
regions on either side); (2) some of the fluid-dynamic character-
istics of this region that could influence the transport of fish
larvae to nearshore and estuarine environments. Moored instru-
ments and cross shelf transects will be used to describe perti-
nent aspects of the physical and biological environment with a
resolution that reflects the intra-annual frequencies of ener-
getic variability in cross-shelf transport. Methodologies will
be combined to describe the time varying strength of the front
and the biomass composition of larval fish, the microplankton
assemblage and the predators present within and on either side of
the front. Bioassays will be used to determine how the survival
and growth of larval fish are affected by the composition and
abundances of food typical of frontal and non-frontal regions.

Aspects of the biology of the Nassau grouper, Epinephelus stria-

Patrick L. Colin, Caribbean Marine Research Center and Lee Stock-
ing Island, Bahamas

The Caribbean Marine Research Center is engaged in a program
of fish resource ecology in the Bahamas with emphasis on western
Atlantic.groupers. The program -is designed to investigate the
entire life history of the local groupers, particularly the
Nassau grouper, in order to obtain biological information useful
in resource management. In this regard the research includes
work on spawning, larval development (both at sea and in the
lab), recruitment, juvenile and adult life with regard to oceano-
graphic factors. Progress to date (since January 1988) has
included collection of adults from spawning aggregations, docu-
mentation of spawning, ichthyoplankton collections in areas of
spawning, laboratory larval rearing work, and monitoring and
collection of recruits. Initial results will be summarized.

Unifying concepts in recruitment

Larry B. Crowder, Department of Zoology, North Carolina State

In this presentation, I will focus on the mechanisms influ-
encing recruitment variation in fish populations. Mechanisms
previously considered to be alternative hypotheses (e.g. starva-
tion, predation, advection) interact and must be considered
jointly. Body size and growth dynamics of larval fish explain a
substantial portion of the variation in the ecological perform-
ance of both freshwater and marine fish larvae. Future recruit-
ment research should focus on the unique characteristics of
survivors rather than on the sources of mortality for the large
number of fish that die. New techniques including otolith analy-
sis and individual based modeling will prove useful in under-
standing recruitment variation. Recruitment variation is often
correlated with both short and long term environmental variation,
but different empirical approaches may be necessary to address
questions at the different temporal scales. The future of re-
cruitment research will require diverse, but integrated, ap-
proaches to the problem.

Reduction and shifts in occurrence of larval and juvenile Sciae-
nidae in the lower St. Johns River, 1980- 88

Carole DeMort and Jan Murphy, Coastal Fisheries Laboratory,
University of North Florida

The occurrence.and distribution of larval and juvenile
members of the family Sciaenidae have been studied from 1980-88
in the lower St. Johns River from Green Cove Springs to Sisters
Creek. Collection methods included plankton nets, hoop nets,
seines, and otter trawls. Preliminary analyses of the data
indicate decreases in total number of larvae collected from the
sampling areas and significant decreases in the juveniles of most
species within the family. This study also indicates a shift in
maximum population densities of both larval and juvenile stages
of spot and croaker from the lower river stations to the more
northern sites within the study area. All members of the genus
Cynoscion appeared to be decreasing in numbers of juveniles
collected at all stations. However, since 1986-87, the number of
juvenile silver perch and star drum appear to be increasing
within the study area. This is part of a larger juvenile fin-
fish- shellfish study that is being carried out in cooperation
with the Florida Game and Fresh Water Fish Commission.

The importance of early-juvenile habitat to Florida Fishery

Randy E. Edwards, Mote Marine Laboratory

Traditional recruitment theory for marine fishes has focused
on processes.like egg production, larval feeding, growth, preda-
tion, transport and dispersal, with recruitment being largely
determined by the end of the larval stage. There is little
doubt, for marine fishes having planktonic larval stages, that
these processes are very important to recruitment. For certain
pelagic or open-sea fishes, recruitment may be almost totally
determined by processes occurring during the larval stage.
However, the life history of many marine and estuarine fishes
includes another stage that is critical to recruitment. This
stage can be termed the early- juvenile (EJ) stage and usually
includes a period of many weeks following metamorphosis.

During the EJ stage, many species have requirements for very
specific types of nursery habitats that are very different from
those of larvae, later juveniles and adults. Although, for a
number of important species, these habitat relationships are not
yet fully known and understood, in most cases they involve very
shallow, marginal and fringing habitats. In the case of estua-
rine species, these EJ habitat relationships also often involve
low salinity conditions. Nursery habitat relationships such as
these have been at least partially elucidated and documented for
several important estuarine fishes, including red drum, snook and
striped mullet. Comparable EJ nursery relationships probably
exist for many coastal species (e.g., grouper, snapper and other
reef fish), but are not as well known. Overall, there is a high
likelihood that the recruitment of many commercially, recreation-
ally and ecologically important species is potentially limited by
availability of suitable EJ nursery habitat and by processes
occurring during the EJ phase.

Another important and practical reason to begin to analyze
relationships between EJ habitats and recruitment is that these
habitats, because of their shallow/fringing character, are highly
subject to anthropogenic alteration and destruction. In Florida,
many of the most important fisheries could become diminished and
totally limited because sufficient productive EJ nursery habitat
is no longer available. In view of the State's rapid population
growth and attendant environmental impacts, analyses of early-
juvenile nursery habitat relationships should be given high
priority in efforts to understand and predict fishery recruitment
in Florida waters.

Predicting fishery recruitment: Florida, the southeast, the

Eugene Fritz, National Seagrant Office

The fisheries resources of the United States are, with a few
notable exceptions, products of coastal ocean waters and adjacent
estuaries. These resources support the Nation's major indus-
tries. However, fish populations and communities fluctuate,
sometimes substantially, from year-to-year and to even greater
extents on longer intervals (interdecadally). This variability
and lack of knowledge of its causes reduce the effectiveness of
resource management and cause economic dislocations so character-
istic to fisheries.

A major goal of fisheries science is the accurate prediction
of the status of species for both short-term (inter and intra-
annual) and long-term (interdecadal) time periods. Most of the
existing forecasting methods are known to be inadequate, particu-
larly in regard to long time scales and radical population
change. Short- term predictions are needed to better set har-
vesting levels and conditions (timing, place, etc.). Long-term
predictions are essential in identifying the booms, collapses,
and changes in community structure that cause the major disloca-
tions in fisheries. Recruitment is the process by which young
fish (or shellfish) are added to the adult or fished stock, and
is, therefore, the essential process on which the continuity of a
fishery depends. Evidence to date suggests that recruitment
variability is intimately linked to the physical dynamics of the
oceans and large-scale climatic fluctuations. Fisheries scien-
tists throughout the world have identified recruitment fisheries
oceanography as the most important topic in fisheries science,
and the key to accurate predictions.

A research program on fisheries recruitment not only has the
potential for improving fisheries management responsibilities,
but also for improving man's understanding of the linkages be-
tween the physical environment and the ocean's productivity.

Seagrass, mangrove swamp and herbaceous halophyte marsh fish
communities, spatial and trophic guilds, faunal overlap, popula-
tion dynamics and the importance of relative habitat associa-

R. Grant Gilmore, Harbor Branch Oceanographic Institution, Inc.

Extensive long-term fish collections, using a variety of
innovative techniques, have provided new information on the
nature of fish communities inhabiting seagrass, mangrove swamp
and herbaceous salt marsh habitats. The distribution of fishes
over a variety of physical, hydrological and structural gradients
in all habitats has been found to be highly predictable. Howev-
er, the relative abundance of various species has been found to
be variable from one annual cycle to another. Despite quantita-
tive changes in populations, a predictable occurrence of various
spatial and trophic guilds is described from all habitats.
Species replacement within these guilds occurs on environmental
gradients which are often of greater importance than qualitative
vegetative change in habitat.

As the definition of microhabitat associations of most
common species show high predictability, it is recommended that
the more complex problem of annual, quantitative variability in
population be considered of high priority in future research
activities. This problem has to be approached with a long-term
interdisciplinary research program which places priority on
climatic and hydrological conditions, particularly during periods
of high mortality, i.e., periods of larval transit from spawning
sites to juvenile habitat. Predatory pressures, trophic competi-
tion and resource availability, along with a variety of other
ecosystem factors which are critical to species survival, need to
be isolated before a rudimentary understanding of population
fluctuations can be obtained.

Predation on Juvenile Spiny Lobster: Who's been eating our

William F. Herrnkind, Mark J. Butler IV, and Kenneth Smith,
Florida State University

Present knowledge suggests that, by far, the greatest natu-
ral mortality in spiny lobsters occurs during the 6-plus month,
planktonic phyllosoma period. True or not, impacts on this part
of the life cycle are pretty much beyond human control and even
useful measure. It is when the post-larval stage comes inshore
that we can first assess its condition and, hopefully, conserve
the recruits. At present, we conserve mainly by protecting the
"nursery" habitat; perhaps later we can enhance recruitment by
increasing settlement, or survival without understanding the
source of natural mortality on the post-larvae and juveniles.
Conditions and events contributing to mortality probably include
as yet undocumented effects from abiotic stresses, such as sea-
sonal or apeariodic salinity reductions, low 02, and severe low
temperature. Continuous impact probably arises from predation.
The questions become, at which age and to what extent? Postlar-
vae can be effectively hunted by piscine and invertebrate preda-
tors in a wide array of microhabitats: in sandy substrate-portu-
nid crabs; just above the substrate -squirrel fishes; midwater -
yellowtail snapper, amidst vegetation white grunts, gray snap-
per. Many other species are certainly among the gauntlet run by
postlarvae between the reef and inshore algae beds. Predation on
juveniles decreases with age (size) but may remain surprisingly
high through the first half year of benthic life. Factors in-
volved include shelter type and distribution as well as the type
and number of local predators. In the Keys the latter include
nurse and bonnethead sharks, and sting rays.

Estuarine spawning of the red drum in Mosquito Lagoon on the east
coast of Florida

Darlene R. Johnson, Department of Fisheries and Aquaculture,
University of Florida, and

Nicholas A. Funicelli, National Fisheries Research Center, U.S.
Fish and Wildlife Service

A study was initiated in the fall of 1987 to determine in
red drum were spawning in Mosquito Lagoon, an estuary on the
Florida east coast. Weekly plankton tows to collect eggs were
taken from mid-September to mid-November, and floating fish eggs
were removed from samples and incubated for 16-36 hours. Three
hundred and twenty-nine red drum larvae were hatched. Red drum
eggs were collected over a four-week period from October 27 to
November 18. Catch salinities ranged form 29 to 32 ppt, while
catch temperatures ranged from 21 to 23 C. This is the first
documentation of red drum spawning in an estuary. Mosquito
Lagoon red drum may be more estuarine-dependent than red drum in
other estuaries.

Cross-shelf distributional ranges of newly settled Haemulids and
Lutjanids (18 species) among several habitat scales and tech-
niques for collecting, visual surveying and field/aquaria manipu-

Ken Lindeman, Division of Biology and Living Resources, Universi-
ty of Miami, RSMAS

To determine complete spatial ranges of larval settlement
and early habitat associations, distributions and abundances of
early life stages of 5+ genera of grunts and snappers have been
examined among barrier island and mainland channel sites of Bear
Cut, Jupiter Inlet, Snake Creek, and adjacent areas of SE Florida
for two to four years. Primary sampling stations include most
habitat types within a windward barrier island to mainland tidal
creek gradient of coastal lagoon communities of northcentral
Biscayne Bay. Habitats surveyed include red mangrove overwash
islands, adjacent ecotones of attached and drift grasses and
macroalgae, grassbed blowouts, and other sedimentary, inverte-
brate, and shoreline tree habitats. Several survey methods are
required to adequately sample settling larvae and juveniles among
this diversity of fine- and cross-scale structural habitats.
When cryptic behavior or identification problems require benthic
collection, particularly useful devices include handnets paired
with hand-held Nitex screens or wheel-mounted pushnets. A varie-
ty of settlement trap and net designs are discussed relative to
specialized water column and benthic sampling needs. Visual
surveys often require inspection of complex microhabitats for
transparent 8-12 mm fishes. Resolution is optimized by staying
close to the substrate to backlight epibenthic larvae, sampling
at MHW + 2 hrs., and the use of lights and angled mirrors when
required. High resolution discrimination in situ of both sizes
and species are critical tools and should be tested and refined
for accuracy. In some genera, distinctive pigment patterns are
fine size references. Live individuals of many species can be
readily transported from water to boat to aquaria in 6 oz. museum
jars. Lab or field manipulation to examine habitat utilization
and feeding among common multispecies assemblages of settling
stages is a ready opportunity.

Mangrove root habitats of windward channels of Bear Cut, N.
Key Largo, and Snake Creek were used by juvenile or newly settled
life stages of over 65 species within 29 families of coastal
marine fishes during this study. Of these, 43 species are com-
monly considered "reef" fishes. Both small, individual Rhizopho-
ra mangle trees

(page 2)

and substantial overwash islands comprise of several intergrown
trees can support large relative abundances of at least 9 spe-
cies of haemulids and lutjanids. These species and Abudefduf
saxatilis can continuously use these habitats for all or most of
the year. Total densities can reach 20+ inds./m2 prop-root and
associated water column habitat. Similar patterns are also
present in mangroves of channel and backreef communities of
emergent reef lines of SW Puerto Rico. Attached sea grasses and
algae, piles of various detached macrophytes, and adjacent sedi-
mentary habitats appear to be primary settlement sites for larvae
of many species. Colonization of mangrove root habitats in many
species is usually via post-settlement immigration by early
juveniles. Periodic tide and storm induced disturbance events
can limit abundances of all life stages of most species.

Newly-settled larvae and schools of early juveniles of at
least 7 species of Haemulon and Lutianus are more abundant in
euhaline estuaries or backreef lagoons than mid-shelf reefs. It
is predicted that two main factors, transient use of mid-shelf
habitats by larvae, and predation mortality on mid-shelf reefs,
determine the observed higher estuarine and backreef abundances
of newly-settled and early juvenile stages -- the actual mecha-
nisms being differential survivorship among communities, behav-
ioral avoidance of deeper environments, or a combination of both
factors. Since within-habitat abundances can differ greatly
among physiographic communities, evaluation of nursery habitat
values will be highly site-specific for many reef and estuarine

Use of otoliths to determine the age and growth of spotted seat-

Michael J. Maceina, South Florida Water Management District

Age and growth was estimated from sectioned otoliths for 426
Spotted Seatrout Cynoscion nebulosus collected from Galveston
Bay, Texas. Marginal increment measurements showed that a single
annulus formed on the otolith during March and April. Agreement
between two independent readers for annulus counts was 99%,
suggesting that age interpretation from sectioned otoliths was
precise. Maximum longevity reported by other workers using
scales was generally six to eight years with one specimen report-
ed to be 10 years old. In this study, I interpreted 12 annuli in
one male fish, thus extending the maximum age known for this
species. Spotted seatrout grew considerably faster in Galveston
Bay, Texas, compared to the Gulf of Mexico in Florida. This
variation in growth rate may be due to genetic differences or
environmental conditions. However, this discrepancy may also be
due to differences in annulus interpretation between scales and

SEFCAR: The University of Miami's southeastern Florida and Carib-
bean recruitment study

Michael F. McGowan, Division of Biology and Living Resources,
University of Miami

Beginning.in 1989,. a multidisciplinary program to study
recruitment of reef fishes and lobsters to the Florida Keys will
focus on the effects of coastal oceanography on distribution,
periodicity, and intensity of subsequent recruitment. Separate
components of the study will include plankton collecting, moni-
toring settlement of juveniles, biochemical characterization of
population genetics, laboratory experiments on reared larvae,
documenting the physical oceanography on multiple time and space
scales, and synthesis through simulation modelling. Interactions
between a gyre, coastal countercurrents, and vertical migrations
of larvae and juveniles will be considered. SEFCAR will inter-
face with and complement ongoing research at other Florida uni-
versities and by state and federal agencies. Anticipated results
should be generally applicable to downstream regions such as the
South Atlantic Bight and to upstream regions in the wider Carib-
bean, in addition to helping to understand and predict recruit-
ment of coastal species in Florida.

Drum prior to recruitment to the offshore spawning population

Michael D. Murphy and Ronald G. Taylor, Florida Marine Research

Current management of red drum in Florida is designed to
increase recruitment.to the offshore spawning stock by reducing
fishing pressure on the inshore subadults. Although age-struc-
tured simulation models have been used to predict management-
associated increases in abundance, direct evaluation of the
effectiveness of these regulations has not been made. During
October-November 1988, the abundance of post- exploited-phase,
subadult red drum was estimated for a 6- sq. mi. area of lower
Tampa Bay using tag-recapture data. Movement and length frequen-
cy data suggested the population examined was essentially closed
to recruitment or emigration during this period. Thorough random
mixing of tagged fish with untagged fish also appeared to occur
within the prescribed sampling area. An estimate of abundance
for catchable, post-exploited- phase subadults was 4,647 (95%
confidence interval: 3,932-5,680). The efficacy of tag-recapture
programs for monitoring recruitment of red drum to the spawning
stock depends on 1) the spatial coverage required during tagging
for estimates of relative abundance to be representative of the
entire population, 2) the precision of abundance estimates, and
3) the strength of the correlation between post-exploited-phase
subadult abundance and spawning stock recruitment.

Pro-active management: Will the lights come on in Florida?

Russel Nelson, Florida Marine Fisheries Commission

Florida's estuarine, coastal and oceanic waters encompass
more than 8,000,000 acres along a 1170 mile coastline and support
thousands of invertebrates, fish, reptiles, and mammals. Over
120 species of fish and invertebrates are harvested on a regular
basis in the state. Commercial and recreational fishing indus-
tries which depend upon these resources generate almost $6 bil-
lion annually in expenditures and revenues in Florida. Unfortu-
nately, the current state of knowledge is insufficient to allow
for efficient, pro-active management of renewable marine re-

Fisheries management in Florida is beginning to move beyond
the stage of crisis intervention. With the prospect of funding
available from a saltwater fishing license, managers are looking
forward to augmenting current catch and effort data with area-
specific fisheries-independent surveys of juvenile and adult
abundance and distribution. In order to use the data generated
by these efforts to develop a comprehensive, predictive manage-
ment capability, we must have a reasonable understanding of basic
life history characteristics, population dynamics, and recruit-
ment dynamics. The Marine Fisheries Commission has developed a
matrix of information needs identifying areas in which we lack
adequate data on the biological, ecological, and physical factors
affecting the abundance and production of renewable marine re-
sources in Florida. This matrix may serve as a starting point
for defining future research goals associated with the recruit-
ment initiative.

In order to effectively assess the effect of current manage-
ment plans and to move towards a predictive management capabili-
ty, we must increase our understanding of the generic, as well as
species-specific, elements which control recruitment variability
in coastal and oceanic pelagics, inshore estuarine-dependent
species, reef fishes -- especially the upper level predators
which sustain the directed fisheries, and transgressive species
such as spiny lobsters, tarpon, and bonefish with long- lived
larval stages and the potential for stock:recruitment relation-
ships over large geographic areas.

Lessons learned from the grunts: Observational studies of re-

John C. Ogden, Florida Institute of Oceanography

The events immediately surrounding recruitment are critical
in the determination of the adult population size and the compo-
sition of communities of coral reef fishes. Grunts (Haemulidae)
are ideal subjects for observation as they have a very short
planktonic larval life compared to other coral reef fishes, are
relatively easily identified, collected and manipulated in the
field, and are prolific in recruitment through broad periods of
the year. Our studies over a number of years at the West Indies
Laboratory in St. Croix, involving many students and colleagues,
were designed to discriminate the importance of recruitment rate
and post- recruitment mortality in the determination of adult
population size.

In a long-term observational study, we monitored recruitment
and population densities of the juvenile size classes of the
French grunt, Haemulon flavolineatum, from October 1978 through
December 1980, in a portion of the reef and associated lagoon in
Tague Bay, St. Croix. The mean annual recruitment rate for the
French grunt is among the highest yet reported for reef fishes:
44/m2 adult habitat/yr. Post-recruitment mortality in this
species is also very high: 0.9 during the first month of benthic
life. Fewer than 8 out of every 10,000 recruits survived for one
year. Using an open, density- independent model of benthic
population dynamics for French grunts, Shulman and Ogden (1988)
estimated that changes in the post-recruitment mortality rate had
a much greater effect on the abundance of adults than did a
proportionate change in the recruitment rate. This same analysis
was applied to other coral reef fishes for which appropriate data
are available. For 2 out of 3 species for which recruitment
limitation has been demonstrated, the same conclusion was

As potentially important as such models are to the under-
standing of population dynamics in fishes, studies of recruitment
with relevance to management must expand their temporal and
geographic scales in order to reasonably encompass the appropri-
ate time-space scales of the process of recruitment in the target
species. For the French grunt, these scales are as compressed,
and therefore as tractable, as we can expect to find in a coral
reef fish. Nevertheless, successful realization of studies at
this level will require unprecedented coordination and integra-
tion of investigators and institutions.

Physical aspects of fishery recruitment

Donald B. Olson, Rosensteil School of Marine and Atmospheric
Science, Division of Meteorology and Physical Oceanography

Recruitment is dependent upon transfers between source
regions for potential recruits and the final environment where an
organism is going to exist in a given life stage. In the marine
environment, this process is often controlled by the nature of
flows found in given regimes and the degree of mixing that occurs
between environments. This control may be direct, as in the case
of planktonic forms, or indirect in the situation where an organ-
ism actively migrates but is still dependent upon navigational
queues which are effected by the fluid motion. While the drift of
inert particles provides a first approximation to the redistri-
bution of plankton in general, behavior is important in both of
these types of interaction with the physical environment. The
Florida marine environment can be separated into three distinct
regimes: the pelagic environments of the Gulf of Mexico and
Florida Current, the shelf, and the semi-enclosed bays and rivers
along the coast. Recruitment occurs in both directions between
these regions. The physical mechanisms for exchange within and
between these three regimes are briefly discussed along with some
of the possible ways in which organisms can exploit or, alterna-
tively, eliminate the effect of these processes. FInally, condi-
tions in the Florida Environment are contrasted with the more
completely understood conditions on the U.S. northeast and west

Recruitment analysis program for the Little Manatee River/Tampa
Bay estuary

Ernst B. Peebles, USF Department of Marine Science

A two-year database is being collected with the purpose of
identifying environmental factors associated with successful
recruitment of the early stages of estuarine-dependent fishes
into nursery habitat. Otolith microstructure will be used to
compare birth-date frequencies calculated from larvae and juve-
niles from the same cohort. A general length-frequency derived
mortality curve will be used to help compensate for mortality
effects on abundance within each stage. Discrepancies between
the birth-date frequencies of the ontogenetically-discrete sam-
ples will then be used to generate time-series data for survival
during protracted spawning seasons. The survival data will be
used in a time-lag correlation function with physical and biotic
data to identify important environmental factors. A wide range
of variables will be available for this analysis, including
phytoplankton and zooplankton counts (food availability) and
physical variables which might influence larval transport.

Roughly 80,000 fish specimens, constituting more than 65
species, have been identified from the first year's plankton
collections. However, due to insufficient data for juveniles of
many of these species (particularly those which are cryptic after
the larval stages), the recruitment analysis will probably con-
centrate on sciaenid and clupeiform fishes.

Fishery research in Florida: A systematic approach to a diversi-
ty of problems

William Seaman, Florida Sea Grant College

The combined freshwater and marine fisheries of Florida
constitute a multi-billion dollar activity. A high diversity of
coastal and oceanic finfish and shellfish species are sought for
commercial and recreational purposes, thereby compounding needs
for scientific information on which to base management. As a
means of ordering its own priorities for research, and to con-
tribute to statewide planning of related programs, Florida Sea
Grant is using a workshop format to identify information needs
related to fishery recruitment in Florida waters. Technical
working groups bring an international perspective to the identi-
fication of state priorities and ways to organize research and

Part III. Appendices

Appendix 1. List of Participants

Scott Andree
Florida Sea Grant Extension
615 Paul Russell Road
Tallahasee, Florida 32301

George 0. Bailey, Jr.
Dept. of Nat'l Resources/FMRI
261 7th Street
Apalachicola, FL 32320

L.W. Barnthouse
Oak Ridge National Lab
P.O. Box 2008
University of North Florida
Oak Ridge, TN 37831-6036

Renee' E. Bishop
Dept. of Nat. Resources/FMRI
100 8th Avenue
St. Petersburg, FL 33701

James A. Bohnsack
75 Virginia Beach Drive
Miami, FL 33149

Steven Branstetter
Dept. of Nat. Resources/FMRI
100 8th Avenue SE
St. Petersburg, FL 33701

Alan Bratkovich
University of Michigan
College of Engineering
2455 Hayward
Ann Arbor, MI 48109-2145

Rich Cailteux
P.O. Box 1903
Eustis, FL 32727-1903

Paul Christian
UGA Marine Extension
P.O. Box Z
Brunswick, GA 31523

M. Elizabeth Clarke
University of Miami
4600 Rickenbacker Causeway
Miami, FL 33149

Walyer C. Conley
Dept. Nat. Resources/FMRI
100 8th Avenue SE
St. Petersburg, FL 33701

Roy Crabtree
Dept. Nat. Resources/FMRI
100 8th Avenue SE
St. Petersburg, FL 33701

Larry B. Crowder
Dept. of Zoology
North Carolina State
Raleigh, NC 27607

Carole DeMorte
Coastal Fisheries Laboratory
University of North Florida
Jacksonville, FL

Randy E. Edwards
Mote Marine Lab
1600 City Island Park
Sarasota, FL 34236

Anne-Marie Eklund
S. Fla. Research Center
Everglades Nat'l Park
Homestead, FL 33030

John H. Finucane
National Marine Fisheries Serv.
3500 Delwood Beach Lab Rd.
Panama City, FL 32405

Denis W. Frazel
Nova Oceanographic Center
8000 N. Ocean Drive
Dania, FL 33004

Eugene Fritz
National Sea Grant College Program
6010 Executive Blvd.
Rockville, MD 20852

B. Grimes
National Marine Fisheries Serv.
3500 Delwood Beach Lab Rd.
Panama City, FL 32408

Joe G. Halusky
NE Florida Sea Grant Extension
233 Marine Center Drive
Jacksonville, FL 32086

Douglas Harper
75 Virginia Beach Drive
Miami, FL 33149

Randy Hockberg
Dept. of Nat. Resources/FMRI
100 8th Avenue
St. Petersburg, FL 33701

Mark Holsbeck
75 Virginia Beach Drive
Miami, FL 33149

Peter Hood
Dept. of Nat. Resourcess/FMRI
100 8th Avenue
St. Petersburg, FL 33701

Donald E. Hoss
Nat'l Marine Fisheries Serv.
SEFC Beaufort Lab
Beaufort, NC 28516

Darlene R. Johnson
Dept. Fisheries & Aquaculture
University of Florida
Gainesville, FL 32609

Sharon Kelley
75 Virignia Beach Drive
Miami, FL 33149

Drew Kendall
UGA Marine Extension
P.O. Box Z
Brunswick, GA 31523

Frank S. Kennedy
Dept. of Nat. Resources/FMRI
100 8th Avenue SE
St. Petersburg, FL 33701

Joseph Kimmel
Dept. of Nat. Resources/FMRI
100 8th Avenue SE
St. Petersburg, FL 33701

Gary Kleppel
Nova Oceanographic Center
8000 N. Ocean Drive
Dania, FL 33004

Mark Lazzari
Dept. Nat. Resources/FMRI
100 8th Avenue SE
St. Petersburg, FL 33701

Ken Lindeman
75 Virginia Beach Drive
Miami, FL 33149

William F. Loftus
Everglades N.P.
P.O. Box 279
Homestead, FL 33030

Mike Maceina
S, Florida Water Mgmt. Dist.
P.O. Box 24680
West Palm Beach, FL 33416

Behzadd Mahmoudi
Dept. of Nat. Resources/FMRI
100 8th Avenue
St. Petersburg, FL 33701

R. E. Matheson
Dept. of Nat. Resources/FMRI
100 8th Avenue
St. Petersburg, FL 33701

B. McClellon
75 Virginia Beach Drive
Miami, FL 33149

Michael F. McGowan
University of Miami
4600 Rickenbacker Cswy.
Miami, FL 33149

John Miller
Department of Zoology
North Carolina State
Raleigh, NC 27607

Mike Mitchell
Dept. of Nat. Resources/FMRI
100 8th Avenue
St. Petersburg, FL 33701

Robert Muller
Dept. of Nat. Resources/FMRI
100 8th Avenue
St. Petersburg, FL 33701

Jan Murphy
Coastal Fisheries Laboratory
University of North Florida
Jacksonville, FL

Michael Murphy
Dept. of Nat. Resources/FMRI
100 8th Avenue
St. Petersburg, FL 33701

Jeff M. Napp
University of Miami
4600 Rickenbacker Causeway
Miami, FL 33149

Russell S. Nelson
FL Marine Fisheries Comm.
2540 Executive Center Circle W
Tallahassee, FL 32301

Joe O'Hop
Dept. Nat. Resources/FMRI
100 8th Avenue SE
St. Petersburg, FL 33701

John C. Ogden
FL Institute of Oceanography
830 First Street S.
St. Petersburg, FL 33701

Don Olson
University of Miami
4600 Rickenbacker Cswy.
Miami, FL 33149

Peter B. Ortner
4301 Rickenbacker Cwy.
Miami, FL 33149

Ernest B. Peebles
USF Dept. Marine Science
140 7th Avenue S.
St. Petersburg, FL 33791-5016

Kevin M. Peters
Dept. of Nat. Resources/FMRI
100 8th Avenue
St. Petersburg, FL 33701

Wes Porak
P.O. Box 1903
Eustis, FL 32727-1903

Ramoll Ruiz-Carus Lee Trent
Dept. of Nat. Resources/FMRI Nat'1 Mar. Fish. Ser.
100 8th Avenue 3500 Delwood Bch. Rd.
St. Petersburg, FL 33701 Panama City, FL 32408
813/896-8626 904/234-6541

Michael Schirripa
S. Florida Research Center
Everglades Nat'l Park
P.O. Box 270
Homestead, FL 33030

William Seaman, Jr.
Florida Sea Grant College
Univ. of Florida, Bldg. 803
Gainesville, FL 32611

Jeff Silverman
RSMAS/University of Miami
4600 Rickenbacker Cswy.
Miami, FL 33149

David L. Sutherland
75 Virignia Beach Drive
Miami, FL 33149

Frederick C. Sutter III
Dept. of Nat. Resources/FMRI
100 8th Avenue
St. Petersburg, FL 33701

Ron Taylor
Dept. of Nat. Resources/FMRI
100 8th Avenue
St. Petersburg, FL 33701

Jim Tilmant
S. Florida Research Center
Everglades Nat'l Park
P.O. Box 279
Homestead, FL 33030

Leslie Kay Timme
Nat'l Marine Fisheries Service
3500 Delwood Beach Rd.
Panama City Beach, FL 32408

Appendix 2. Workshop Agenda


Wednesday February 15, 1989

14:00 15:15 Plenary Session

15:15 15:30 Break

15:30 16:30 Contributed Papers

16:30 16:45 Break

16:45 18:00 Contributed Papers

18:00 19:00 Dinner


Begin Poster Session

19:30 20:30 Contributed Papers

20:30 21:15 Discussion: Themes of the workshop



Thursday February 16, 1989

08:00 09:00

09:00 10:00


workshop goals and major questions
Instructions to working groups

10:00 12:00 Working Group Session:
Select working group leaders & recorders
Identify important/representitive species

12:00 13:00 Lunch

13:00 14:00 Discussion: Initial progress reports

14:00 17:00 Working Group Session:
Consider comments from discussion session
Evaluate the existing data on recruitment of
key species
Identify physical processes important to
recruitment of key species

17:00 18:00

Identify generic and non-generic components
of recruitment
Describe principal data needs

18:00 20:00 Dinner

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