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Final SEDAR workshop report for the Goliath Grouper Assessment.
The
Goliath Grouper in Southern Florida: Assessment Review and Advisory Report Report prepared for the South
Atlantic Fishery Management Council Gulf of Mexico Fishery Management Council
National Marine Fisheries Service Edited
by Michael C.S. Kingsley for the Southeast Data and Assessment Review February 2004 Kingsley, M.C.S., ed. 2004.
The Goliath Grouper in southern Florida: assessment review and advisory report.
Report prepared for the South Atlantic Fishery Management Council, the Gulf of
Mexico Fishery Management Council, and the National Marine Fisheries Service.
Southeast Data and Assessment Review. vii + 17 pp. CONTENTS Preface The SEDAR Review Process
........................................................................................................v Purpose of the Terms of
Reference and Advisory Report
...............................................................vi Acknowledgments.......................................................................................................................vi Background on the Goliath Grouper........................................................................................................ l Terms
of Reference for the Review of theAssessment Adequacy and
appropriateness of data
...........................................................................................1 Adequacy, appropriateness, application and results of models used to assess stocks .......................... 5 Adequacy, appropriateness, application and results of models used to estimate population benchmarks ...............7 Adequacy, appropriateness, application and results of models used for rebuilding analyses ...............8 Recommendations for improving data collection and assessment and future research ........................ 8 Additional Comments.............................................................................................................................. 9 Stakeholder
Comments From Ralph Allen...................................................................................................................9 From Marianne Cufone and Don DeMaria ...............................................................................9 From Dennis O'Hern............................................................................................................10 From Richard Taylor ............................................................................................................10 Conduct of Future Workshops ............................................................................................................... 11 Annex Ie Advisory Report .............,....................................................................................................... 13 Stock Identification and Distribution ...........................................................................................13 State of Stock.............................................................................................................................13 Table...................................................................................................................................13 Management Advice...................................................................................................................13 Forecasts ...................................................................................................................................13 Table...................................................................................................................................14 Catches......................................................................................................................................14 Data and Assessment..................................................................................................................14 Biological
Reference
Points........................................................................................................14
Table...................................................................................................................................14 State of Stock.............................................................................................................................14 Recruitment ...............................................................................................................................15 Stock Biomass ...........................................................................................................................15 Special Comments......................................................................................................................15 Sources of Information
...............................................................................................................15 Figure 1. Estimated trend in biomass, 1950-2020..................................................................16 Figure 2. Trends in relative abundance for 3 surveys of Goliath Grouper ................................. 16 Annex II: Glossary and
Abbreviations...................................................................................................
17 PREFACE Summary
of the SEDAR review process The
South Atlantic Fishery Management Council, the Gulf of Mexico Fishery Management
Council, and the Caribbean Fishery Management Council, in conjunction with NOAA
Fisheries, have adopted the Southeast Data, Assessment and Review (SEDAR)
process, a multi-step method for determining the status
of fish stocks. SEDAR is structured around three workshops: 1) Data Workshop, 2)
Stock Assessment Workshop and 3) Review Workshop. Participants in Data Workshops
review input data, including catch statistics, fishery sampling and population
monitoring data, and species life history. Participants in Assessment Workshops
develop stock assessment models, estimate values for population parameters and
stock status benchmarks, and project future population conditions. At Review
Workshops an independent peer review panel provides a technical review of the
data and of the assessment methods. The relevant Council committees, such as the
Science and Statistics Committees, must then certify the final assessment report
before it can become eligible for use in developing management actions. The goal
of SEDAR is to provide an open and transparent process for developing and
reviewing scientific information that is critical to management of species in
the Southeastern United States, including the South Atlantic, Gulf of Mexico,
and Caribbean. The SEDAR process includes data collectors, biologists,
fishermen, environmental representatives, database managers, stock assessment
scientists and Council members and staff. The Goliath Grouper (Epinephelus itajara) has been identified
as a species of concern, and was proposed for SEDAR Assessment. A workshop on
the data available for the Goliath Grouper was held on 5-6 March 2003'. The
participants concluded, from a review of the data presented to them, that the
data available on the species were not adequate to support a full assessment
even in waters restricted to southern Florida, and still less adequate for the
entire range of the species. However, as the report of the workshop mentions,
another data set was identified after the meeting that
might contribute to an assessment. 1 Anon. n.d. [2003.] Goliath
Grouper data workshop report. SEDAA3-DW-1. 11 pp. vi A
subsequent SEDAR Review Panel2 revisited the question of an
assessment of the Goliath Grouper and considered that "not conducting an
assessment on this occasion had likely been an incorrect decision. It was
suggested that the assessment option for Goliath Grouper be revisited at an
early opportunity, initially
looking specifically at assessment models that could operate in a data-poor
arena." This
recommendation was acted upon and an assessment document was prepared 3;
however, no assessment workshop was held at which the assessment could be
examined or other models compared with the one that was used. Instead, the
assessment document was presented to an Assessment Review Panel, normally the
third and last stage of the SEDAR process, at a meeting in Tampa, Fla on 27-30
January 2004. The present document reports the results of that meeting. It does
not present the assessment itself, but the Review Panel's views on the validity
and limitations of both the assessment and the data upon which it was based. An
Advisory Report, prepared by the Review Panel, and based on the conclusions it
could draw from the assessment as to the current state of the stock and
forecasts for its future, is appended. Purpose
of the Terms of Reference and Advisory Report The
`Terms of Reference Report' provides a brief review of the stock assessment and
the underlying data, with the SEDAR Assessment Review Panel's conclusions about
the adequacy and appropriateness of both. The report does not repeat the
detailed results of the assessment. An `Advisory Report' on stock status and
possible and appropriate management for the stock in accordance with SFA
prescription is appended; however, as the Panel is specifically enjoined not to
conduct an alternative assessment, the Advice that can be formulated is bounded
by the adequacy of the assessment(s) that is (are) reviewed. Acknowledgments Thanks are due to the members of the SEDAR
Assessment Review Panel who participated in the review-Ralph Allen (GMFMC
Advisory Panel; Independent), Luiz Barbieri (GMFMC Scientific and z
SEDAR Peer Review of Yellowtail Snapper Assessment, with comments on Goliath
Grouper (Tampa, Florida, 2831 July, 2003). Porch,
C.E., A.-M. Eklund and G.P. Scott. 2003. An
assessment of rebuilding times for Goliath Grouper. SEDAA6-RW-3. Contribution
SFD-2003-0018, Sustainable Fisheries Div., SE Fisheries Science Center, National
Marine Fisheries Service, Miami, Fla. 25 pp. Statistical Committee;
Florida Fish and Wildlife Conservation Commission), Jon Brodziak (Reviewer;
Northeast Fisheries Science Center, NMFS), Marianne Cufone (Reviewer; The Ocean
Conservancy), Don DeMaria (SAFMC Advisory Panel; Independent), Michael Kingsley
(Chairman; Center for Independent Experts), Debra Murie (GMFMC Finfish
Assessment Panel; University of Florida), Michael Murphy (GMFMC Finfish
Assessment Panel; Florida Fish and Wildlife Conservation Commission), Julie A.
Neer (Reviewer; Southeast Fisheries Science Center, NMFS), Jay Rooker (GMFMC
Finfish Assessment Panel; Texas A&M University), Richard Taylor (GMFMC
Reviewer; Independent), Eddie Toomer (GMFMC Advisory Panel; Independent) and
John Wheeler (Reviewer; Center for Independent Experts). We thank the presenters
and other scientific staff for their work beforehand and for their presentations
at the meeting, and the members of the public, the fishermen, divers, and
others, for cooperative and constructive input to the review meeting. We thank
the staff of the Fishery Management Councils, the National Marine Fisheries
Service and other organisations for their contributions to the running of the
meeting and for their input to the Review Panel's deliberations. BACKGROUND
ON THE GOLIATH GROUPER. The Goliath Grouper (Epinephelus itajara) is a long-lived reef fish
that grows to unusually large size: fish weighing several hundred pounds are not
unusual. Outside the spawning season, adults are typically solitary, sedentary,
and territorial, unafraid and somewhat inquisitive; these characteristics make
them an easy target for spearfishing. The species takes hooks easily, so is also
vulnerable to angling. The large size it can reach makes it impressive as a
trophy, but also makes it difficult to handle with the care necessary to ensure
its survival on release. These factors combined to create an overfishing
situation that depleted numbers in southern Florida and elsewhere, and the
Fishery Management Councils imposed a moratorium on landings in 1990. Since
then, anecdotal accounts and quantitative survey data agree that numbers of both
adults and juveniles have increased, although a subjective consensus appears to
be that pristine stock levels have not been reached. Prevailing comment on the
state of the stock ranges from concern over the still-depleted numbers and
reported continuing mortality from poaching and other fishing-mortality of
released fish whether caught intentionally or as by-catch is reported to be
high-to irritation at the effect of an increasing abundance of large territorial
adults in restricting both the numbers, and the availability to divers, of other
reef species. I
TERMS OF REFERENCE FOR THE REVIEW OF THE GOLIATH GROUPER ASSESSMENT. Evaluate
the adequacy and appropriateness of fishery-dependent and fishery-independent
data used in the assessment (i.e., are the input data scientifically sound and
up to date?). hery-independent
data comprised two time series consisting of visual-survey counts of adult fish
carried out by divers4. The first series (made by Mr D. DeMaria) had
the following characteristics: few (5) sites, all relatively distant from the
coast in the eastern Gulf of Mexico; all observations were made by one observer;
a 21-year series (1982-2002; although not at all sites were surveyed over the
entire period). The second, made by the Reef Educational and Environmental
Foundation (REEF), was a nine-year series covering 1994-2002. It had many sites,
all relatively close to land in the reef tract off the east coast of Florida and
the southern edge of the Florida Keys. Observations were made by many different
observers but the methods were standardized, and all the counts were censored at
a maximum of 4 Porch,
C.E., and A.-M. Eklund. 2003.
Standardized visual counts of goliath grouper off south Florida and their
possible use as indices of abundance. Contribution SFD-0017, Sustainable
Fisheries Division, SE Fisheries Science Center, NMFS, Miami, Fla. two
fish sighted. Both series were census-type surveys. There was no mention of the
collection in the course of either survey of other data, such as estimated
length. The first series was
questioned with respect of how well it reflects the abundance or density of the
species over its entire range in south Florida waters. The fact that a single
observer collected the data was considered a strength of the series, but its
limited coverage of a small set of similar sites in a restricted area
remained a concern. It was not clear whether these sites represent the
predominant range for the species in the long term: observations were cited of
historical aggregations near shore in shallow water in many locations around the
coast. However, anecdotal observations were advanced that indicated broadly
similar trends in other areas of western Florida further north, and it was also
observed that the overall trend of the series is supported by that of the
Everglades National Park creel survey series. It was concluded that the data
series was acceptable for the assessment. The
inclusion of the data from 1982 and 1983 in the DeMaria series was also
questioned. The assessment that was presented had omitted both these years on
the grounds that large reductions in numbers observed from 1982 to 1984
reflected intensive fishing subsequent to, and consequent on, discovery of these
sites and may therefore represent a localized effect. This decision was
questioned. One of the arguments for including those two points was that the
sites might have been fished before the survey was begun in 1982. Additionally,
fishery landings data, which had been excluded at the data workshop, signaled a
40% drop in landings at the same time. However, the commercial landings were
subject to problems of both over- and under-reporting, and therefore such a drop
in commercial landings was not considered to be a reliable indicator of a
corresponding reduction in overall stock abundance. more,
including the 1982 data impaired the agreement between this series and the
others. The Review Panel's final recommendation was to include the 1983 data,
but to exclude the 1982 data from the assessment. The REEF diver survey along
the Florida reef tract was accepted for use in the assessment with little
discussion. The censoring of the data at 2 fish per survey station was
considered unlikely to be significant in terms of the assessment, since the
numbers of observed Goliath Grouper in this survey were overall very
small. The inclusion of a data series from a geographical fringe of the
distribution was considered an advantage, because it might help the aggregated
data to track the trend of the species in more of its range. Another
set of data consisted of subjective estimates of the decline in stock
size between 1950 and 1990 obtained by telephone interviews with 9 experienced
fishermen and divers who were active over the whole period. The Panel considered
these estimates acceptable for the assessment. The
fishery-dependent data available consisted of a single creel-survey series from
the Everglades National Park (ENP)-where coastal mangroves are principally
considered habitat for juvenilescovering 1973-1999 and reporting catch and
effort from a total of 165,734 trips5. The data were restricted to
14,026 trips that reported catching Goliath Grouper or species deemed, from
analysis of the total set, `associated' with Goliath Grouper. This restricted
set was used to calculate a catch:effort series as an index of abundance of the
sub-adult segment of the stock. Effort per observation was estimated. The
restriction method used on the ENP data series was discussed. Among the points
raised were that some of the associations determined by the association analysis
were biologically unconvincing, and suggestions were made both that the
association threshold should be made more stringent and that it should
be relaxed 6. No consensus was reached for changing the
assigned value either way, and the threshold was left unchanged. It was pointed
out that the restriction was a numerical exercise to avoid gross biases due to
time trends in the proportion of trips that were directed completely away from
Goliath Grouper habitat. There was discussion on the effect of including all
trips that caught Goliath Grouper, regardless of the presence of associated
species, in the restricted set, but no consensus was reached that it induced a
bias that would be significant to the assessment. The
Review Panel considered that this data series, and the treatment to standardize
the catch: effort ratios, were acceptable for the assessment. There was a
question about whether the relationship between catch: effort ratios and density
would be different before the fishery was closed from after, but it was pointed
out that even after the moratorium on landings of Goliath Grouper was
instituted, a directed catch-and-release fishery continued. There were
additional discussions on whether the skill of fishermen 5
Cass-Calay, S.L., and T.W.
Schmidt. 2003. Standardized catch rates of juvenile Goliath Grouper, Epinephelus itajara, from
the Everglades National Park Creel Survey, 1973-1999. SEDAR6-RW-2. Contribution
SFD-20030016, Sustainable Fisheries Div. SE Fisheries Science Center, National
Marine Fisheries Service, Miami, Fla. 17 pp. 6
It transpired after the Review
Panel meeting that Cass-Calay and Schmidt had in fact tested the effect of different values of the association criterion. A
more stringent value, excluding more species and more trips, gave trends in
catch:effort ratios that were almost identical with those used. A lower, more
inclusive, value gave trends that were somewhat more exaggerated-faster decrease
at the beginning, faster increase at the end-but not very different. in
continuing to find fish, even when becoming scarce, could cause catch: effort
ratios to be a non-linear indicator of average density. By
means of an existing age-length curve 7, the
ENP data were also used to calculate age-specific vulnerabilities to the fishery
before the moratorium, and age-specific relative abundance after the moratorium
for age classes within this stock segment (ages 0 to 5). The Review Panel
questioned whether vulnerability in the pre-moratorium fishery might have
reached asymptote as late as 9 or 10 yrs, and the sensitivity of the assessment
to such a change was investigated. However, the study that suggested this
hypothesis was not available to the Panel for review, nor designed to get this
type of information. The Panel concluded to retain the vulnerability curve
originally proposed. Landings
data from NOAA Fisheries exists for 1950-1990. This series ended with the
imposition of the moratorium. The series had problems with both over- and
under-reporting and is of limited relevance in the current state of the stock
and the fishery, but might provide loose corroborative evidence for the trend of
the population decline. Some catch-rate, and possibly mark-recapture, data exist
from a tagging study on juveniles in the Ten Thousand Islands and Florida Bay
area. These two data series were not used in the assessment. Other
life-history data were used in stock-dynamics modeling. Natural mortality
estimates in the literature were used together with estimates derived from
published longevity to generate a prior distribution for natural
mortality"''°. It was pointed out that the longevity estimate
was obtained from ail exploited population and could possibly underestimate the
true natural longevity. Additional methods of determining longevity were
discussed but no definite recommendations were made. Existing age-length and
length-weight curves were used to generate a surrogate for age-specific
fecundity. Metadata from Bullock,
L.H., M.D. Murphy, M.F. Godcharles and M.E. Mitchell. 1992. Age, growth and
reproduction of jewfish Epinephelus itajara in the eastern Gulf of Mexico. Fish. Bull. 90: 243-249. 8
Legault, C.M., and A.-M.
Eklund. 1998. Generation times for Nassau grouper and jewfish with comments
on M/K ratios. Contribution SFD-97/98-10A, Sustainable Fisheries Division,
Southeast Science Center, National Marine Fisheries Service, Miami, Fla. 9
Hoeing, J. 1984. Empirical use of
longevity data to estimate mortality rates. Fish. Bull. 81(4): 898-903. 1°
Sadovy, Y., and A.-M. Eklund.
1999. Synopsis of biological data on the Nassau grouper, Epinephelus striatus (Bloch, 1792), and the jewfish, E.
itajara (Lichtenstein, 1822). NOAA
Tech. Report NMFS 146. 65 pp. other
`periodic strategist' fishes was used to generate prior distributions for
parameters of the stockrecruitment relationship...... Overall,
the Review Panel considered that the data used were scientifically sound.
However, the data sets available were very limited, and restricted the type of
assessment model that could be built, and therefore the conclusions that could
be drawn from it. Evaluate
the adequacy, appropriateness, application and results of models used to assess
stocks (e.g., measures of exploitation, abundance, and biomass). The
stock to be considered was not defined. The data available were limited to
southern Florida waters. The relationship between stocks, or sub-stocks, in
these different areas appears not to be well known. The meeting therefore
considered that it was reviewing an assessment covering all Goliath Grouper in
waters off Florida south of 26°N. Conclusions from the assessment are
restricted to the areas covered by the data. Visual surveys to count
adults (DeMaria and REEF surveys) were standardized using a stepwise approach to
build general linear models of logged counts, so that year effects could be
isolated. In addition to year, location and season effects were statistically
significant. The diagnostic statistics of the model fits were satisfactory, and
visual surveys were thought to give valid indices of abundance for adults. Catch
rates of juveniles from creel survey data were standardized with sequential
fitting of models to proportion successful trips and to catch per unit of effort
(CPUE) of successful trips. Retained factors in the proportion of successful
trips were whether trips targeted Goliath Grouper or not and year. Retained
factors from the analysis of the CPUE of successful trips included year, skill
level of the fishing party, fishing area, and an interaction between year and
area. Diagnostic statistics were again satisfactory. The Review Panel considered
that these treatments of the series of abundance indices were acceptable. "
Rose, K.A., J.H. Cowan, K.O. Winemiller, R.A. Myers and R. Hilborn. 2001.
Compensatory density dependence in fish populations: importance, controversy,
understanding and prognosis. Fish and Fisheries 2: 293-327. 12
Myers,
R.A., and G. Mertz. 1998. Reducing uncertainty in the biological basis of
fisheries management by metaanalysis of data from many populations: a
synthesis. Fish. Res. 37: 51-60. It
was remarked in the report of the data workshop and in assessment documents that
no measures of absolute abundance exist for any stock segment, and no data from
which any such measure could be based. Therefore, all deductions on abundance
from assessment modeling are relative to a pristine stock state; deductions on
fishing mortality are, by contrast, absolute. An
assessment model was built to trace stock trajectory from an assumed pristine
state in 1950 through increasing fishing mortality to low stock levels, the
moratorium in 1990 and subsequent increasing indices of abundance. Stock levels
in the model were expressed relative to pristine. Stock structure was governed
by age-specific natural mortality and age-specific vulnerability to
year-specific fishing mortality. Vulnerability was assumed to follow an
increasing logistic. Recruitment was governed by weight at age in the spawning
stock and pre-recruitment mortality. The model was fitted to
data using Bayesian methods, and ancillary information was sought to create
informative priors, including stock-recruitment relationships. Under the
assumption of a linear increase in fishing mortality from 1950 through 1979, the
stock structure was tracked back to its pristine state. The
stock trajectory fitted the series of standardized abundance indices reasonably
well. Three
sensitivity trials were carried out. 1) 1950 was replaced by 1900 as the year
for which the stock state was assumed pristine. The result of this sensitivity
trial showed that recovery was lengthened by several years under the altered
assumption. It was recommended to retain the 1950 starting point. 2)
When the age of full selectivity in the model was increased from 6 years to
about age 10 years, rebuilding would already have occurred, with 50%
probability, by 2002. 3) The model showed that predictions of rebuilding time
were very sensitive to the assumed on-going fishing-induced mortality after the
moratorium was imposed. When it was assumed that the moratorium only reduced
fishing mortality to 20% of its pre-moratorium level (i.e. 80% effective), the
model suggested that the stock would be unlikely to recover. The
Review Panel recognised the importance of estimating the present mortality in
trying to predict rebuilding times. However, even after much discussion, and
considering anecdotal evidence of on-going mortality, the Panel could not reach
a single conclusion on its magnitude for lack of data. By consensus, it
was agreed that it would be reasonable to bracket a range at end-points of 10%
and 1% of premoratorium fishing mortality in order to provide an illustrative
range of rebuilding-time predictions'3. The
Review Panel considered that the models used were appropriate for the available
data, and adequately addressed questions of exploitation and relative abundance,
within the limits of the data. Evaluate
the adequacy, appropriateness, application, and results of models used to
estimate population benchmarks and Sustainable Fisheries Act status
determination criteria (e.g., MSY, F„sY, Bmsy, MFMT,
MSST, and OY). In
the absence of estimates of biomass, it was not possible to estimate all
standard stock benchmarks. MSY and other benchmarks referencing absolute biomass
could not be estimated. An MSST relative to pristine stock state could be
estimated. The
model, and the available data, are together adequate for estimating fishing
mortality reference points, such as fishing mortality corresponding to any
percentage SPR, and a wide range of other fishing mortality benchmarks. FmsY
could not be reliably estimated on account of concerns over selectivity
and the exact stock-recruitment relationship. The
Review Panel used a proxy for F,nsy, Fso%oSPR, in accordance with the Gulf
Council's selection of that proxy in its generic SFA Amendment. FSO%,sPR was
also the proxy for Foy used by the South Atlantic Council, which in Amendment 11
to its FMP for the snapper/grouper complex had selected F4o%>SPR as its proxy
for F,,,Y. The
Review Panel considered that OY, which depends on socio-economic and other
inputs, is outside its scope. '3 After the
meeting, two members of the panel expressed reservations about the use of a
value of 90% as an `ineffective' endpoint of the illustrative range, considering
it likely that the moratorium had been even less effective than this would
imply. (See also 'Stakeholder Comments' below.) Evaluate
the adequacy, appropriateness, and application of models used for rebuilding
analyses where appropriate, and estimate, to the extent possible, generation
time and rebuilding time in the absence of fishing mortality. The
Review Panel reviewed the assessment model as a device for predicting rebuilding
times for this stock, and considered the model to be adequate for estimating
rebuilding times for any level of F. The Panel did not consider a scenario in
which current and future fishing mortality is zero. The Panel did not review the
available information on generation time 8 as it was not part of the
current assessment. Develop
recommendations for improving data collection and assessment and future research
(both field and assessment). The Review Panel concurs with the
recommendations of the data workshop that the following topics be pursued in
research programs on the Goliath Grouper. It recommended the following rough
priority listing, as determined by the difficulty encountered in treating these
topics in the course of this review: Estimation
of population size: Estimates of population size were
considered to be of highest importance for future management. It was noted that
because of the apparently restricted home range and high site fidelity
characteristic of adults, sampling throughout the geographic range would be
important. Tag/recapture studies were mentioned as a potential monitoring tool. Estimates
of on-going mortality The issue of ongoing mortality was of
critical concern to the Review Panel. Anecdotal information with regard to
various sources of this mortality was presented. These sources included longline
by-catch, post-release mortality, and illegal harvest. It is extremely important
that these sources of ongoing mortality be identified and the magnitude of this
mortality estimated. Investigations
of stock structure: This question was repeatedly raised. The
assessment reviewed by the Panel was of necessity limited to south Florida owing
to the geographic coverage of the data and the absence of data concerning the
stock structure. Demographics:
Monitoring the demographics of the population, particularly age
composition, could provide valuable information. Reproductive biology_ Developing
further understanding of the reproductive biology of Goliath Grouper was
considered important. Historical abundance and exploitation:
Obtaining information on historical abundance was also considered important. Survey
data. While the Review Panel considered it in the highest degree
important to continue the current surveys, it recommended that data collection
could be improved by extending survey efforts to better cover the full
historical range of the stock. ADDITIONAL
COMMENTS There were none. III STAKEHOLDER COMMENTS From Ralph Allen: `The fact that adult Goliath
Grouper heavily aggregate at a small number of well known and easily located
sites would make them extremely vulnerable to rapid depletion in the event that
a directed fishery were ever opened.' From
Marianne Cufone and Don DeMaria: `We are uncomfortable with the assumed values
of postmoratorium fishing mortality on Goliath grouper. The discussion was
difficult to follow and keep in perspective, as it ranged back and forth between
the panel and the audience and discussion of assumptions regarding mortality
rates, mortality reductions, moratorium effectiveness, and the number of fish
killed per 100 in the population. Upon further consideration and reviewing the
final assumed values, assuming the moratorium is 90-99% effective might be
overly optimistic. The mathematics of these stock assessments is quite
impressive, but we fail to see how unknown parameters such as human nature and
environmental conditions can be factored into an equation. Considering the slow
growth and long life of Goliath grouper, the number of dead Goliath grouper
observed, and reports of fish being intentionally killed, we feel more
comfortable erring on the side of conservation and not attempting to estimate
moratorium effectiveness.' From Dennis O'Hern of Largo, Fla, recreational
angler, diver, spearfisher and representative for the Florida Skin Divers
Association (FSDA) whose numbers represent over 500 divers: `Goliath Grouper
populations in our area of West Central Florida, roughly north of the 26 degree
latitude line, are large, growing and becoming increasingly aggressive toward
divers. Examples of the over-population abound, with local anglers and divers
reporting goliath encounters on every wreck in the area. Even small, natural
ledges are holding one or two medium to large fish. A small wreck will hold 6
fish at least, with the Mexican Pride (a popular local wreck) having 25 or more that
appear to exceed 300 #. Many local divers, including myself, have been bumped
aggressively and had fish taken from them by these large grouper. `There are no scientific
estimates or ideas of total jewfish population whatsoever. A value needs to be
determined for virgin stock levels or even 1950s stock levels. Responsibility
for the definition of a specific value continues to be passed from one entity to
another. Without the value, there is no way to declare the Goliath population
recovered. In the meantime, the goliath population is growing rapidly and
unchecked at an admittedly unknown rate. This species's over-protection must be
having some detrimental effects on other species' populations. By their sheer
numbers, goliaths are consuming large quantities of shellfish and fish. No
consumption data is currently available. `All
data used seemed to revolve around one of the nursery areas for goliaths, along
with a few sites in the southwestern gulf. The data from the Gulf sites are the
anecdotal observations of one individual. `The non-natural mortality
rate discussion considered what percentage of the population was poached or
killed unnaturally, with no quantitative data being presented. The figure of one
percent was discussed. That is ten thousand poached fish per million, a figure
that is way too high. Even a thousand fish per million is too high. There is
simply no evidence of poaching or non-natural mortality that would make one
percent even close to a reasonable estimate. This one value can swing the
goliath from being considered recovered today, to not being recovered for at
least 15 more years.' From
Richard Taylor: `Extensive visual evidence by the 60 members of
the St. Petersburg Underwater Club (SPUC) shows a dramatic increase in Goliath
Grouper populations occurring west of the Tampa Bay Peninsula. Goliath Grouper
are being observed in all age sizes and locations. Many solitary fish are being
observed at the area's numerous local ledges and outcroppings.
Larger structures often hold a dozen or more Goliaths. The incidence of
non-natural mortality was debated at length during the SEDAR workshop. SPUC
members strongly believe that the incidence of non-natural mortality occurring
is 10 miniscule compared to the
overall population and statistically insignificant. SPUC members have not seen
nor heard of any unlawful incidents with regard to Goliath Grouper and no
evidence of a high rate of non-natural mortality was presented during the SEDAR
workshop.' RECOMMENDATIONS
FOR THE CONDUCT OF FUTURE WORKSHOPS The review would have been
facilitated if the assessment had been examined by an assessment workshop. It
would have been helpful to have the authors of all the relevant documents
available to make presentations and answer questions. ANNEX
1: ADVISORY REPORT Advisory
Report Goliath Grouper Stock
Identification and Distribution: The stock is not defined and the current
distribution of the species is not completely known. The conclusions of this
assessment are applicable to Goliath Grouper within the limited area covered by
the available data. State
of Stock: Goliath Grouper in south Florida (south of latitude 26° N) are
overfished, and overfishing may or may not be occurring, depending on the
effectiveness of the moratorium, which is unknown. Fishing-related mortality is
known to occur, but lack of data prevents estimation of rates. If the moratorium
has been at least 90% effective in reducing fishing mortality, overfishing is
unlikely, and biomass in 2003 could be estimated as 76% of the target biomass,
taken to be that corresponding to 50% SPR. If the moratorium had been 99%v
effective, biomass in 2003 would be predicted to lie at about 91% of the target
biomass. Indications from the assessment were that the biomass has continuously
increased since imposition of the moratorium. Status Table: Goliath Grouper relative biomass and estimated fishing
mortality, 1993-2002 with
maximum, minimum, and mean for 1950-2002.
(Catch was considered unreliable and
was not included in the stock assessment.) 1993
1994 1995 1996 1997 1998 1999 2000 2001 2002 max mean
i Moratorium
90% effective 2 B/B,ef3 0.22 0.25 0.28 0.34 0.41 0.49 0.56 0.62 0.67 0.72 2.27 0.12
0.78 F4(/yr)
0.026 0.026 0.026 0.026 0.026 0.026 0.026 0.026 0.026
0.026 0.254 0.010 0.124 Moratorium
99% effective 5 B/B,f3
0.25 0.29 0.33 0.39 0.48 0.57 0.65 0.72 0.79 0.85 2.34 0.14 0.84 F4(/yr)
0.002 0.002 0.002 0.002 0.002 0.002 0.002 0.002 0.002
0.002 0.237 0.002 0.111 1
Statistics based on estimates for
entire period 1950-2002. z
Le. fishing-induced mortality under the moratorium has been set for illustrative
purposes at 10% of estimated premoratorium (1979-1990)
fishing mortality. 3
B,f is taken to be B50I,SPR 4F for 1990-2002
is the stated proportion (10% or 1%) of
the estimated pre-moratorium F. 5
Le. fishing-induced mortality
under the moratorium has been set for illustrative purposes at 1% of estimated
premoratorium (1979-1990)
fishing mortality Management
Advice: The moratorium should be maintained at least until a future assessment
shows that the biomass achieves the rebuilding target. Any fishery could risk
rapidly depleting the stock, and would require careful monitoring. Forecasts: Forecasts of future biomass were
critically dependent upon the level of fishing mortality during the moratorium,
but were also associated with large uncertainties due to imprecise fits of the
model to available data. When these two sources of uncertainty are combined, the
year by which the biomass in south Florida waters can be expected (with 80%
confidence) to be rebuilt is estimated to lie between 1999 and sometime beyond
2020 (Figure 1). 13 Forecast Table: Forecast point estimates of biomass relative to MSST,
2003-2012, for two illustrative values of moratorium effectiveness. Moratorium Effectiveness
2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 B/B,ef 90%
0.76 0.81 0.85 0.89 0.93 0.97 1.01 1.05 1.08 1.11 99%
0.91 0.98 1.04 1.10 1.16 1.22 1.28 1.34 1.39 1.45 Catches:
The stock is under moratorium. There are data on catch and release, mostly of
juveniles, but no data on associated mortality and no data on poaching or other
directed takes, or on by-catch. Catch data prior to the moratorium are
considered unreliable. Data
and Assessment: An age-structured production model was fitted to visual count
data from offshore south Florida in the eastern Gulf of Mexico, catch and effort
data from inshore mangrove habitat in Everglades National Park, and visual count
data from the Florida Atlantic Reef Tract (Figure 2). The model assumed a
pristine stock in 1950, fishing mortality increasing linearly with time until
1979, and stable fishing mortality from 1980 until 1990 when the moratorium was
imposed. Assessment runs were made under suppositions that the moratorium had
been 90% or 99% effective. No data were available to support either supposition.
No reliable catch data were available to tune the model, which therefore
provided a trajectory of relative biomass. Biological Reference Points: Absolute values of
biological reference points related to biomass (MSY, OY) are not available.
Point estimates of F,,,y range between 0.083/yr and 0.093/yr. The point estimate
of Fso%sPR is 0.095/yr. MSY is assumed to occur at Fso%sPR based on the current
generic SFA Amendment adopted by the Gulf of Mexico Fishery Management Council,
and at Fao%SPR based on Amendment 11 to the South Atlantic Fishery Management
Council FMP for the snapper-grouper complex. Given the life history and low
natural mortality of Goliath Grouper, the Review Panel recommends that the MSST
proxy be (1-M)*B„,5,,. Biological
Reference Points Table. Goliath Grouper in South Florida, for two illustrative
levels of moratorium effectiveness. Effectiveness
of Moratorium ( (Flxfore - Fafler)/Fbefore ) 90%
99% Estimate SE
Estimate SE Fmsy (/yr)
0.09
0.0174
0.08
0.0190 Fsoq
sPR(/yr)
0.05
0.0158
0.05
0.0159 F401/,, SPR (/yr)
0.07
0.021
0.07
0.021 Fishing
Mortality: The assessment model assumed fishing mortality to increase linearly
from a low value in 1950 to a plateau in 1979. Estimated maximum annual fishing
mortality was around F=0.25/yr, experienced from 1979-1989. The moratorium is
known to be imperfect. Assessment runs were made under suppositions that it had
reduced the fishing mortality by 90% or 99% of the maximum. No data were
available to support either supposition. 14 Recruitment:
No estimates of recruitment are available. Stock
Biomass: The assessment was limited to southern Florida waters. Only relative
measures of biomass are available. Relative biomass has increased steadily since
the moratorium was imposed in 1990, at which time it appears that biomass had
fallen to around 5% of the pristine level. 2002 biomass is estimated to be 31%
of pristine if the moratorium were 90% effective, and 36% of pristine assuming
99% moratorium effectiveness. Three independent surveys indicated that biomass
has increased since the early 1990s (Fig. 2). Special Comments: The panel
noted that it is difficult to infer stock status owing to a lack of reliable
catch data and to the limited geographic range of available survey data. A stock
definition combined with expanded monitoring efforts to cover the stock range
would benefit future assessment efforts. Sources of Information: Porch, C.E. and A.-M.
Eklund. 2003. Standardized visual counts of goliath grouper off south
Florida and their possible use as indices of abundance. SEDAR6-RW 1, 25pp. Cass-Calay,
S.L. and T.W. Schmidt. 2003.
Standardized catch rates of juvenile goliath grouper from the everglades
national park creel survey, 1973-1999. SEDAR6-RW2. 17pp. Porch,
C., A.-M. Eklund and G.P. Scott. 2003. An
assessment of rebuilding times for goliath grouper. SEDAR6-RW3. 23pp. Anon. n.d. [2003]. Goliath
grouper data workshop report. SEDAR3-DWL 11 pp. B/Bref for range of moratorium effectiveness L
-90% -=
-
0 i
I-- 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995
200O 2005 201O 2015 202O Year Figure
1. Estimated trend in biomass relative to the reference biomass from 1950 to
2020 for two assumed levels of moratorium effectiveness. 6 54 cc 3jX
2
REEF DeMaria ENP .0 -* 0 i
:Z:~
I
1
1 1972 1977 1982 1987 1992 1997 2002 Year Figure 2. Trends in
relative abundance for 3 surveys of Goliath Grouper. ANNEX 11: GLOSSARY AND ABBREVIATIONS B
stock biomass level Bmsy
value of B capable of producing MSY on a continuing basis B,ef value of B used as a proxy
to represent B„,Sy B5or sPR
value
of B corresponding to 50% of the spawning potential in an unfished stock CPUE
catch per unit of effort ENP
Everglades National Park GMFMC
Gulf of Mexico Fishery Management Council F
(instantaneous) fishing mortality F,,,sy
fishing mortality to produce MSY under equilibrium conditions F5o%o sPR
fishing mortality that will result in B5o% sPR
under
equilibrium conditions M
(instantaneous) natural mortality MFMT
maximum fishing mortality threshold, a value of F above which overfishing
is deemed to be occurring MSST
minimum stock size threshold, a value of B below which the stock is
deemed to be overfished MSY
maximum sustainable yield (equals F„,5,, times
B„,5,,) NMFS
National Marine Fisheries Service NOAA
National Oceanographic and Atmospheric Administration OY
optimum yield REEF
Reef Educational and Environmental Foundation SAFMC
South Atlantic Fishery Management Council SEDAR
Southeast Data, Assessment and Review SFA
Sustainable Fisheries Act of 1996 SPR
spawning potential ratio, stock biomass relative to an unfished state of
the stock
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