SSC Report to CFMC

SSC Report to CFMC146th CFMC Meeting held June 24, 2013SSC Meeting held June 19 20, 2013

SEDAR 30: Assessed blue tang and queen triggerfish TIP data from 1981 - 2011Juvenile blue tangAcanthurus coeruleusQueen triggerfish Balistes vetula

L. Johnson, FishbaseBarbara KojisSchool of primarily blue tang at Buck Island St. Croix, USVI

Goal of SEDAR 30Determine stock status for blue tang and queen triggerfishGiven data limitations abundance could not be determinedConducted mean length analyses to evaluate stock status in terms of mortality

U.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 4Data sources reviewed during SEDAR 30Marine Recreational Fisheries Statistics Survey (MRFSS) Puerto Rico onlyCommercial landingsBy island platform and gearTrip Interview Program (TIP)Life history informationPublished literatureU.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 5MRFSS in Puerto RicoBlue tangFive intercepted trips that retained or indicated discarding blue tangTwo length measurementsQueen triggerfishLess than 20 intercepted trips per year retained or discarded queen triggerfishSixty length measurementsWas not used for assessmentU.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 6Commercial landingsUSVI1974-1995 - catch reported as snapper/grouper or finfish1997 reported to species groupSurgeonfishesTriggerifshesPuerto RicoSpecies specificKnown problems with under-reportingCommercial landings were not used for assessmentU.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 7Puerto Rico: self-reported 7

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11Trip Interview Program Blue tangU.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 12IslandGear typeNumber of SamplesNumber of years sampledAverage number of samples per year-Pots & traps621-Puerto RicoHook & line111Puerto RicoNets121620.2Puerto RicoPots & traps1963.2St. Thomas/ St JohnHook & line21210.5St. Thomas/ St JohnNets2237.33St. Thomas/ St JohnPots & traps299621142.6St. CroixHook & line90330St. CroixNets14621597.5St. CroixPots & traps32220291111The trip interview program is a shore based sampling program developed by the Southeast Fisheries Science Center. It was developed to collect data that are not normally included in logbook data sets.Data collected include:Size informationOccasionally biological samples, which included age and reproductive informationSpecies composition of catchGear types used during fishing trip

Data are collected by port samplers 12Trip Interview Program Queen triggerfishIslandGear typeNumber of SamplesNumber of years sampledAverage # of samples per year-Pots & traps1222-Puerto RicoDive/Spear/By Hand10112638.8Puerto RicoHook & line9332833.3Puerto RicoNets11572644.5Puerto RicoPots & traps491728175.6St. Thomas/St JohnDive/Spear/By Hand616St. Thomas/St JohnHook & line2971224.75St. Thomas/St JohnNets221St. Thomas/St JohnPots & traps773121368.14St. CroixDive/Spear/By Hand6441253.67St. CroixHook & line3131226.08St. CroixNets3775.28St. CroixPots & traps802528286.61The trip interview program is a shore based sampling program developed by the Southeast Fisheries Science Center. It was developed to collect data that are not normally included in logbook data sets.Data collected include:Size informationOccasionally biological samples, which included age and reproductive informationSpecies composition of catchGear types used during fishing trip

Data are collected by port samplers 13Mean length analysisLength-frequency data were adequate for the pot and trap fisheries for both speciesExcept in Puerto Rico for blue tangUsed the Gedamke-Hoenig mean length estimator to obtain estimates of total mortality and evaluate how mortality has changed over time U.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 14Puerto Rico: self-reported 14Mean length analysisU.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 15

Puerto Rico: self-reported 15Mean length analysisBeverton-Holt mean length mortality estimatorU.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 16

length at which all animals are fully vulnerable to gearmean lengthtotal mortalitygrowth rate maximum lengthPuerto Rico: self-reported 16TIP length-frequency data blue tangU.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 17

N = 860N = 498N =223N = 66N = 499N = 840LC around 18-19cm17TIP length-frequency data blue tangU.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 18

N = 13201N = 3340N =11771N = 2104N = 629N = 1175LC around 18-19cm18

TIP length-frequency data queen triggerfishU.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 19N = 2631N = 323N =1062N = 536N = 37N =328LC ~ 29cm19

TIP length-frequency data queen triggerfishU.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 20N = 2224N = 876N =495N = 276N = 3221N =638LC around 3420

TIP length-frequency data queen triggerfishU.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 21N = 3919N = 888N = 2168N = 757N = 199N =94LC ~ 2821Blue tang life history informationU.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 22Length -ageLt = L(1-eK(t- to))Locationtmax (years)Lmax (mm)LKtonSourceSan Blas16-183 SL0.477-0.310110Choat and Robertson (2002)Belize15242 FL188 FL1.030-0.15092Mutz (2006)Los Roques20285 FL199 FL0.390-0.11281Mutz (2006)Margarita20335 FL---74Mutz (2006)San Blas16261 FL231 FL0.4900.251110Mutz (2006)Asencion37-193 FL0.403--Choat and Robertson (2002)Lee Stocking27-174 FL0.817--Choat and Robertson (2002)Asencion37304 FL244 FL0.420-0.092112Mutz (2006)Bermuda43250 FL203 FL1.010-0.412105Mutz (2006)Lee Stocking27256 FL219 FL0.880-0.41977Mutz (2006)Blue tang growth curvesU.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 23Queen triggerfish life history informationU.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 24Length -ageLt = L(1-eK(t- to))Locationtmax (years)Lmax (mm)LKtonSourceJamaica-447 FL-0.570--Aiken (1975)PR-546 FL----Bohnsack and Harper (1988)STT & STJ-465 FL----Bohnsack and Harper (1988)PR & USVI7-415 FL0.300-0.600494Manooch and Drennon (1987)PR-760 FL----Pagn 2002St. John-385 FL----Randall (1962)USVI-572 FL----Randall (1968)Brazil14460 FL441 FL0.140-1.800476de Albuquerque et al. (2011)south Florida-425 FL----Bohnsack and Harper (1988)Brazil-450 FL----Menezes (1979)Queen triggerfish growth curvesU.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 25Mean length analysisModel is run first assuming no change in mortality and then with increased complexitySensitivity analysis was conducted to characterize uncertainty in the mortality estimates

U.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 26Puerto Rico: self-reported 26Blue tang, St. ThomasU.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 27

Lc = 19cm, L = 23.1cm, K = 0.49

Z1983 = 0.09Z1984-2010 = 0.4Figure 12. The model fit to the blue tang length data from the St. Thomas/St. John pot and trap fishery. The model fit shown predicts one change in total mortality and had the lowest AIC value. The input parameter values used were Lc = 19cm, L = 23.1cm, and K = 0.49. Bubble size represents the annual sample size scaled with respect to other years.

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Comparison of fishing mortality and natural mortalityBlue tang, St. Thomas/St. JohnU.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 28FrequencyCumulative percentF/MComparison of fishing mortality and natural mortalityBlue tang, St. CroixU.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 29

FrequencyCumulative percentF/MQueen triggerfish , Puerto RicoU.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 30

Lc = 29cm, L = 41.5cm, and K = 0.3y-1Figure 15. The fit to the queen triggerfish mean length data from the Puerto Rican pot and trap fishery. The model fit shown predicts one change in total mortality and had the lowest AIC value. The input parameter values used were Lc = 29cm, L = 41.5cm, and K = 0.3y-1. Bubble size represents the sample size scaled with respect to other years.

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Comparison of fishing mortality and natural mortalityQueen triggerfish, Puerto RicoU.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 31FrequencyCumulative percentF/MQueen triggerfish , St. Thomas/St. JohnU.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 32

Lc = 34cm, L = 41.5cm, and K = 0.3y-1 Figure 18. The model fit to the queen triggerfish mean length data from the St. Thomas/St. John pot and trap fishery. The model fit shown predicts no change in total mortality and had the lowest AIC value. The input parameter values used were Lc = 34cm, L = 41.5cm, and K = 0.3y-1. Bubble size represents the sample size scaled with respect to other years.

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Comparison of fishing mortality and natural mortalityQueen triggerfish, St. Thomas/St. JohnU.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 33FrequencyCumulative percentF/MQueen triggerfish , St. CroixU.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 34

Lc = 28cm, L = 41.5cm, and K = 0.3y-1Z = 0.7Z = 1.07Figure 20. The model fit to the queen triggerfish mean length data from the St. Croix pot and trap fishery. The model fit predicts a single change in total mortality and had the lowest AIC value. The input parameter values used were Lc = 28cm, L = 41.5cm, and K = 0.3y-1. Bubble size represents the sample size scaled with respect to other years. 34

Comparison of fishing mortality and natural mortalityQueen triggerfish, St. CroixU.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 35FrequencyCumulative percentF/MMain conclusions from AW report for blue tang:Puerto RicoThe AW panel decided that data was insufficient to conduct length-based analysis.St. Thomas / St. JohnResults from length-based analysis suggests that total mortality increased, Year of change and magnitude of change was variable among the sensitivity runs.Uncertainty about whether fishing mortality is higher than natural mortality (i.e., proxy for FMSY).Annual length-frequency data have been relatively stable over the time series.St. CroixResults from length-based analysis suggests that total mortality increased in 1983 (first year of available data),Magnitude of change was variable and dependent on parameter inputs.Uncertainty about whether fishing mortality is higher than natural mortality (i.e., proxy for FMSY).Annual length-frequency data have been stable between 1984-2012. U.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 36Main conclusions from AW report for blue tang:General conclusionsAvailable age-growth relationships suggest two possible explanations of growth (k = 0.4 or k = 0.8-1) adding to the uncertainty surrounding the mortality estimatesWell-designed growth studies are needed for this speciesAge-growth relationship erodes at an early age relative to the blue tang life spanLength analysis may be inappropriate for this speciesCollection of catch-at-age data may be more appropriate to adequately describe changes in blue tang population structure. U.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 37Main conclusions from AW report for queen triggerfish:Puerto RicoResults from length analysis suggest that total mortality declined in 1998 or 1999, An increase in mean length can be due to reduction in mortality or expansion to relatively unfished areas.Without detailed spatial catch data, it is difficult to separate these effectsUncertainty about whether fishing mortality is higher than natural mortality (i.e., proxy for FMSY).USVIResults from length analysis suggest that mortality has remained unchanged in St. Thomas/ St. John over time and increased in St. Croix in 1985 or 1986.Industry representatives indicated that they release queen triggerfish >45cm. Violates model assumption of knife-edge selectivityMakes it difficult to interpret absolute mortality estimatesGeneral conclusionsAvailable life history information suggested two different life strategies for queen triggerfishAge and growth studies are neededU.S. Department of Commerce|National Oceanic and Atmospheric Administration|NOAA Fisheries|Page 38SSCs Review of SEDAR 30The SSC accepted the results for queen triggerfish and blue tang as the best available at this time recognizing the following limitations:

Lack of life history information

Low information content provided by the length frequency data for blue tang because of its determinant growth

Potential violation of model assumptions because of dome shaped selectivity for queen triggerfish in STT/STJ due to discards of large fish

Uncertainty in the data due to inconsistencies in annual sample size and non-randomness of samples

Inability to address biomass benchmarks due to considerable uncertainty in landings data

Conclusions - Queen triggerfishThe SSC concluded that the results of SEDAR 30 are consistent with the current status determination in PR and STT/STJ, which is that queen triggerfish is not undergoing overfishing.

However, the result for STX indicates that overfishing might be occurring.

Conclusions - Blue TangResults were too uncertain to be used for status determination

Blue tang does not appear to be targeted in PR based on lack of reported landings

Given the above, the SSC finds no basis for changing the ABCs for queen triggerfish and blue tang.RecommendatonsFor blue tang length analysis is not appropriate and the SSC recommends collecting catch at age data to inform an age-structure model.

For the queen triggerfish in St. Croix, the SSC recommends that approximately 500 length measurements be taken within the next year to inform further analysis.

There is an urgent need for local age and life history parameters for the two species. Without the basic life history and age information, the assessments will continue not to be very informative for scientific advice and management. The SSC understands that a new collection of otoliths is under way and recommends that a carefully designed sampling protocol be implemented.

Validation of catch data including expansion factors is also urgently needed.Derivation of fishing mortality-based references points and the determination of overfishing status of queen snapper and silk snapper captured in the US CaribbeanJune 19, 2013SEFSCMiami, FloridaReview of SEDAR 26Assessed speciesQueen snapper, Etelis oculatusSilk snapper, Lutjanus vivanus

Island platforms and gear types were assessed separatelyQueen snapperPuerto Rico, hook and lineSt. Croix, hook and lineSilk snapperSt. Croix, hook and line

D. Bryan, FishBase.orgT. Meyer, FishBase.orgDuring SEDAR 26 two of the species we assessed were queen snapper and silk snapper

Most consistent species-specific among the island platforms is the length data from the Trip Interview Program44Review of SEDAR 26DataTrip Interview Program (TIP)Annual length dataMost consistent species-specific data among the platforms

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The bars of the length-frequency histograms represent 10mm bins, all lengths were converted to fork lengthRed bar represents the mid-point of a particular size bin with the highest count, this represents the length-at-vulnerability for that 5-year time-period.Sample size was extremely low for the majority of years, so 5-year time-period was chosen to increase the sample size.

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Review of SEDAR 26Gedamke-Hoenig mean length estimatorComputationally attractive for data limited situations Minimal data inputsLength-frequency data Mean length and length-at-full recruitmentLife-history parameters von Bertalanffy growth parametersProvides estimates of total mortalityFishing mortality can be derived from total mortality and estimates of natural mortalityDoes not assume population is at equilibriumEstimates temporal changes in total mortality

48Review of SEDAR 26Uncertainty in assessmentLife history parameters were highly uncertain Sensitivity analysis was conductedConducted assessment over a range of the input parameters

As I mentioned, key model inputs are the von Bertalanffy growth parameters and as it turns out there was limited growth information about queen and silk in the literature. The data limitation was a key uncertainty in the assessment.

To account for the uncertainty we conducted a sensitivity analysis over a range of the input parameters.

Talk about proportional change in Z

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SEDAR 26 Assessment ConclusionsQueen snapper, hook and line fishery in St. CroixNo evidence to suggest overfishing

Change in Z was not detected, only have absolute estimates of Z

Fairly stable size structure over the time period in which data were collected

50SEDAR 26 Assessment conclusionsSilk snapper, hook and line fishery in St. CroixTemporal changes in total mortality were not statistically supportedLow sample size in more recent years obscured the relationship between change in size and change in mortality51

Silk Snapper St. Croix Hook and LineN=158N=2985N= 373N=133N=31N=515N=1775Fork length (10mm bins)Frequency1983-19871988-19921993-19981999-20022003-20072008-2011All yearsSEDAR 26 Assessment ConclusionsQueen snapper, hook and line fishery Puerto RicoNo evidence to suggest overfishingProportional change in total mortality was estimated to be less than 1Fishing mortality less than FmsyRequired assumptions:First year of data collection represents the start (or close to the start) of the fishery and Initial estimate of total mortality is equal to natural mortality (Z~M)Fmsy ~ M

53Per recruit analysisGoals of analysis: Derive fishing mortality reference pointsFmax maximum of the yield per recruit (YPR) curveF0.1- slope of YPR curve that is 10% of the slope at the originF30% - F that allows survival of 30% of spawning biomass per recruitCompare reference points to currents fishing mortality estimatesRe-evaluate overfishing statusCompare to estimates of current fishing mortality to reference points and determine probability of fishery experiencing overfishingDerived from estimates of current total mortality from the sensitivity analysis and estimates of natural mortality (F = Z - M)54Per recruit reference pointsF0.1Fmax & F30%Spawning Biomass per RecruitYield per RecruitFishing mortalityYPRSBPR55Per recruit analysisGoals of analysis: Derive fishing mortality reference pointsFmax maximum of the yield per recruit (YPR) curveF0.1- slope of YPR curve that is 10% of the slope at the originF30% - F that allows survival of 30% of spawning biomass per recruitCompare current fishing mortality estimates to reference points and determine the probability of fishery experiencing overfishingDerived from estimates of current total mortality from the sensitivity analysis and estimates of natural mortality (F = Z - M)During SEDAR 26 two of the species we assessed were queen snapper and silk snapper

Most consistent species-specific among the island platforms is the length data from the Trip Interview Program56Age schedule and model assumptions

Example of the age schedule and corresponding model assumptions. These change slightly with the von B input parameters.

Survivorship, probability of living from one age to the next, is a exponentially declining function of age

A knife-edge relationship was assumed for vulnerability and maturity at the age of full recruitment

Weight-at-age was assumed to follow von Bertalanffy growth relationship and derived from the von Bertlanffy growth parameters and the length-weight power model. 57Probability of overfishing Queen snapper, hook and line fishery in Puerto Rico

100806040200Cumulative percentFcur/F0.10.0 0.5 1.0 1.5 2.0 2.5 3.0 3.53530252015105Frequency058

Probability of overfishing Queen snapper, hook and line fishery in Puerto Rico100806040200Cumulative percentFcur/Fmax0.0 0.5 1.0 1.535302520151050Frequency59

Probability of overfishing Queen snapper, hook and line fishery in Puerto Rico

1008060200Cumulative percentFcur/F30%0.0 0.1 0.2 0.3 0.4 0.5252015105040Frequency60

Probability of overfishing Queen snapper, hook and line fishery in St. Croix

10080604020030Fcur/F0.1 1 2 3 4 5Cumulative percent2520151050Frequency3561Probability of overfishing

100806040200Fcur/FmaxCumulative percentFrequency50403020100Queen snapper, hook and line fishery in St. Croix 0.0 0.5 1.0 1.5 2.0 2.562

Probability of overfishing Queen snapper, hook and line fishery in St. Croix

1008060200Cumulative percentFrequencyFcur/F30% 0.0 0.5 1.0 1.5 2.0 2.5 40302010063

Probability of overfishing Silk snapper, hook and line fishery in St. Croix

100806040200Cumulative percent86420Frequency 0 1 2 3 4Fcur/F0.164

Probability of overfishing Silk snapper, hook and line fishery in St. Croix

100806040200Cumulative percent 0.0 0.5 1.0 1.5Fcur/FmaxFrequency302010065

Probability of overfishing Silk snapper, hook and line fishery in St. Croix

100806040200Cumulative percentFrequency10864200.0 1.0 2.0 3.0Fcur/F30%66ConclusionsInterpretation of overfishing status varied among the reference pointsAnalysis highly dependent on the input value of the von Bertalanffy growth coefficient through the derivationsAge-at-recruitmentNatural mortalityUsed to derive fishing mortality from estimates of total mortalityUsed to derive survivorship-at-age All rely on estimates of k67SSC Review of SEDAR 26 and New ApproachEstimates of current F were derived from a specific time period that at least in the case of queen snapper is not consistent with the years used to calculate average catch.

The available evidence indicates that overfishing probably has not occurred through 2008 and the queen snapper were probably not overfished. The current status of the stock is unknown since the most recent length frequency data included in the assessment was 2008 data.A true harvest control rule is not possible as no reliable estimates of biomass exist and the approach presented is approximately a constant F scenario.

Adjusting the current ABC (Allowable Biological Catch) by any ratio assumes that existing average catch derived ABC is appropriate. Discussion and RecommendationsThe SSC recognized the uncertainty in methodology due to uncertainty in life history parameters. The SSC RECOMMENDS that regional age-growth studies be conducted. For queen snapper, otoliths are already in storage and should be analyzed as soon as possible.

The SSC RECOMMENDS that the most recent length based data be included in the mean length analysis aspect of the approach.

Ideally, if ratios were to be used to modify OFLs then the time period for average landings should correspond to the time period for the mean length analysis. However, this presumes the landings data are reliable.

The SSC looked at years used to calculate average catch and found that slightly different time series had little effect on the value for average catch which corresponds to OFL.

The SSC spent most of first day discussing the expanded landings data for PR and the extremely high variability that has been observed in recent years. A number of members believed the high fluctuations are not a reflection of reality. The SSC strongly recommends that expansion factors be evaluated again and that reported landings alone be evaluated. Discussion and Recommendations continued70Discussion and Recommendations continuedThe SSC is concerned that reporting for Queen Snapper has changed and that reporting behavior is driving the recent overages. Implications: Fishers could have harvested more in the past so the current OFL is too low, or alternatively that current harvest rates are higher than expected and status is unknown.

It was noted that, according to a Federal Register notice, the SEFSC needs to determine if overages result from a situation where data collection and monitoring improved rather than because catches actually increased. Apparently, the SEFSC concluded that data collection and monitoring had not improved and that catches actually increased, but the SSC understands that tracking the number of reporting fishers or individual/representative fishers over the recent time period hasnt been presented.

RECOMMENDATION: Reporting behavior and validation of landings needs to be studied and tracked over time to be able to adequately evaluate the difference between overages and changes in reporting.

Discussion and Recommendations continuedThe SSC recalls that the ACL was based on an average catch during a reference period and adjusted by a coefficient of 0.85 because the stock was considered to be undergoing overfishing. A coefficient of 0.9 was used for stocks for which overfishing was not occurring. In light of our current assessment, the later coefficient (0.9) might be more appropriate.

SUMMARY statement: Both the SEDAR 26 results and the information presented from the new methodology suggests that overfishing is not occurring, although the assessment is too uncertain to be confident, and there isnt much room for further development of the fishery. (It was pointed out that the analysis shows some probability that overfishing is occurring.) The SSC is concerned about the reliability of expanded catch data and uncertainty in life history estimates.

The SSC concluded that at this time there was no scientific basis for modifying the ABC.