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Goliath Grouper South Atlantic Fishery Management Council Scientific and Statistical Committee meeting April 6, 2011.

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Presentation on theme: "Goliath Grouper South Atlantic Fishery Management Council Scientific and Statistical Committee meeting April 6, 2011."— Presentation transcript:

1 Goliath Grouper South Atlantic Fishery Management Council Scientific and Statistical Committee meeting April 6, 2011

2 SEDAR 23: Goliath Grouper, Epinephelis itajara, in Southeast United States Stock Assessment Review November 15-17, 2010 Key West, FL Florida Fish and Wildlife Conservation Commission Fish and Wildlife Research Institute St. Petersburg, FL

3 Goliath Grouper Comprises a single stock in the U.S. (so far as is known) –South Atlantic and Gulf of Mexico regions combined –Most of the landings are in south Florida –Landings data are potentially biased. Thought by some to be a protogynous hermaphrodite, but evidence is not conclusive.

4 Goliath Grouper Some effort was devoted to developing historical time series of landings –Adjustments to commercial landings followed the GMFMC Amendment 2 adjustment method for 1978-1984, and extended these adjustments back to 1962. –Additional commercial landings data added from the Florida State Board of Conservation for 1942- 1950. –Other historical landings data added from the Bureau of Commercial Fisheries publications back to 1918. Gaps were filled using loess smoothing and interpolation.

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6 Goliath Grouper Recreational landings –Landings in terms of numbers are available from the Everglades National Park Angler Creel Survey (ENP), the Head Boat Survey (HBS), and the Marine Recreational Fishery Statistics Survey (MRFSS) –However, few lengths and weights from these surveys were taken, so converting numbers to weights harvested is problematic. This is a particular problem for goliath groupers since the size and weight varies greatly, and even large individuals may be caught close to shore. –Estimating discards is another issue especially for the HBS.

7 Goliath Grouper Maximum age –37 years (known), but the species has been heavily fished. This may be an underestimate. –The “base” run incorporated the known maximum age for goliaths along with other SEDAR 23 parameters, but should be considered as only one of the alternative runs for the assessment. [There is uncertainty over some of the basic biological parameters for this species.]

8 Groupers - max. age, TL

9 Goliath Grouper Younger fish found in mangrove habitats, and begin to move to offshore habitats around ages 3-7 years. Females mature ~ 6-7 yrs Males mature ~ 4-6 yrs

10 Goliath Grouper Model Selection –The lack of time series of landings precluded the use of most other assessment models. The catch- free model used in SEDAR 6 was chosen for this assessment. This model provides relative benchmarks of population status. –Some preliminary exploratory runs with Stock Reduction Analysis (SRA) were performed using the adjusted commercial landings series.

11 Catch-free model Fisheriesnone Ages1 to 25+ years Age composition Length measurements converted with fisheries specific age-length keys to apply to indices. Natural mortalityAge-specific following Lorenzen curve averaging 0.12 per year for ages 3-37 years. TuningThree fishery-independent indices and two fishery-dependent indices Maximum Lifetime FecundityBayesian (from meta-analyses) Moratorium effectivenessBayesian (from data workshop)

12 Sensitivity runs Natural mortality varied using maximum ages (37, 40, 50, 60, 70, 80 years) Moratorium effectiveness estimate was varied There were a total of 17 sensitivity runs. Variability in outcomes examined using MCMC There were no runs incorporating index values covering the January 2010 cold kill.

13 SEDAR 23 Review Panel The reviewers rejected the assessment –The assessment did not meet the Terms of Reference, and could not provide the necessary management benchmarks. –The review panel felt that there were insufficient data available to conduct an assessment. –The review panel felt that different types of models could be explored in the future to provide management benchmarks. –The review panel recommended that additional effort be directed towards estimating historical commercial and recreational landings, and that once these were available analyses with models like SRA (Stock Reduction Analyses) might yield suitable management advice. –The review panel also endorsed several research recommendations for data gathering.

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16 Catch-free model results by run configuration. These results were not accepted by the review panel as representing the current status of goliath grouper in the southeastern U.S. Note: steepness = α / (4+α), and was between 0.81 and 0.90 except for the continuity run (0.69).

17 SEDAR 23 – “base” run ( not accepted by the review panel )

18 Max. age 37 years, Φ3 (moratorium effectiveness) =SEDAR 23 Max. age 50 years, Φ3 (moratorium effectiveness) =SEDAR 23


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