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Ancillary Indices of Abundance for Black Sea Bass Working towards healthy, self-sustaining populations for all Atlantic coast fish species or successful.

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Presentation on theme: "Ancillary Indices of Abundance for Black Sea Bass Working towards healthy, self-sustaining populations for all Atlantic coast fish species or successful."— Presentation transcript:

1 Ancillary Indices of Abundance for Black Sea Bass Working towards healthy, self-sustaining populations for all Atlantic coast fish species or successful restoration well in progress by 2015

2 Overview The goal of the following presentation is to provide the SSC with information that they did not have during consideration of the black sea bass stock assessmentThe goal of the following presentation is to provide the SSC with information that they did not have during consideration of the black sea bass stock assessment The point is not to second guess previous decisions but to supplement the existing informationThe point is not to second guess previous decisions but to supplement the existing information This may allow for a case to be made to allow modest increases in harvest in this fisheryThis may allow for a case to be made to allow modest increases in harvest in this fishery

3 Data Treatment Raw data from fishery independent trawl surveys conducted by the Atlantic Coastal states was gatheredRaw data from fishery independent trawl surveys conducted by the Atlantic Coastal states was gathered The data were analyzed in a consistent fashion to provide some standardization between the different surveysThe data were analyzed in a consistent fashion to provide some standardization between the different surveys The surveys range throughout the biological range of black sea bassThe surveys range throughout the biological range of black sea bass

4 Data Treatment Black sea bass abundance (# fish) information was used from each datasetBlack sea bass abundance (# fish) information was used from each dataset A consistent set of metrics were examinedA consistent set of metrics were examined EThe metrics chosen were ones that were consistent amongst datasets There are indications of zero inflation in the indicesThere are indications of zero inflation in the indices To account for the zero inflation, the datasets were pivoted against the various metricsTo account for the zero inflation, the datasets were pivoted against the various metrics EData rows were dropped in ranges or categories of the metric where there were less than 5 fish for the entire time series In each case, the distribution of the data was analyzed, and is presentedIn each case, the distribution of the data was analyzed, and is presented

5 Data Treatment It was found that the distributions in each survey followed a negative binomial distributionIt was found that the distributions in each survey followed a negative binomial distribution A negative binomial generalized linear model was performed on the datasetsA negative binomial generalized linear model was performed on the datasets Full models were run and then non significant variables were removed, the simplified model was rerunFull models were run and then non significant variables were removed, the simplified model was rerun In each case, if additional modifications to the dataset were performed, it is noted with a justificationIn each case, if additional modifications to the dataset were performed, it is noted with a justification

6 VIMS Trawl Survey Data distributionData distribution

7 VIMS Trawl Survey Data distribution – zeroes removedData distribution – zeroes removed

8 VIMS Trawl Survey Both MONTH and TEMP were signif, dropped MONTH as it’s a proxy for TEMPBoth MONTH and TEMP were signif, dropped MONTH as it’s a proxy for TEMP Model: ABUN ~ YEAR + TEMP + DEPTH + SAL + DOModel: ABUN ~ YEAR + TEMP + DEPTH + SAL + DO

9 New Jersey Trawl Survey Data distributionData distribution

10 New Jersey Trawl Survey Data distribution – zeroes removed and abundance truncatedData distribution – zeroes removed and abundance truncated

11 New Jersey Trawl Survey Both MONTH and TEMP were signif, dropped MONTH as it’s a proxy for TEMPBoth MONTH and TEMP were signif, dropped MONTH as it’s a proxy for TEMP Model: ABUN ~ YEAR + TEMP + DEPTHModel: ABUN ~ YEAR + TEMP + DEPTH

12 NEAMAP Trawl Survey Data distributionData distribution

13 NEAMAP Trawl Survey Data distribution – zeroes removed and abundance truncatedData distribution – zeroes removed and abundance truncated

14 NEAMAP Trawl Survey Both MONTH and TEMP were signif, dropped MONTH as it’s a proxy for TEMPBoth MONTH and TEMP were signif, dropped MONTH as it’s a proxy for TEMP Also STATION field was a unique identifier, not a station, so droppedAlso STATION field was a unique identifier, not a station, so dropped Model: ABUN ~ YEAR + TEMP + DEPTHModel: ABUN ~ YEAR + TEMP + DEPTH

15 NY Peconic Bay Trawl Survey Data distributionData distribution

16 NY Peconic Bay Trawl Survey Data distribution – zeroes removedData distribution – zeroes removed

17 NY Peconic Bay Trawl Survey Four years with 0 or 1 abundance removed from analysis (1987,1989,2005,2010)Four years with 0 or 1 abundance removed from analysis (1987,1989,2005,2010) Model: ABUN ~ YEAR + TEMP + STATIONModel: ABUN ~ YEAR + TEMP + STATION

18 Long Island Sound Trawl Survey Data distributionData distribution

19 Long Island Sound Trawl Survey Data distribution – zeroes removedData distribution – zeroes removed

20 Long Island Sound Trawl Survey Several years removed from analysis due to missing covariatesSeveral years removed from analysis due to missing covariates Model: ABUN ~ YEAR + TEMP + DEPTHModel: ABUN ~ YEAR + TEMP + DEPTH

21 Rhode Island Trawl Survey Data distributionData distribution

22 Rhode Island Trawl Survey Data distribution – zeroes removedData distribution – zeroes removed

23 Rhode Island Trawl Survey Full model wouldn’t converge. Used output as a guide and removed non signif variablesFull model wouldn’t converge. Used output as a guide and removed non signif variables Model: ABUN ~ YEAR + TEMPModel: ABUN ~ YEAR + TEMP

24 MA Inshore Trawl Survey Data distributionData distribution

25 MA Inshore Trawl Survey Data distribution – zeroes removedData distribution – zeroes removed

26 MA Inshore Trawl Survey Only one month in the survey so droppedOnly one month in the survey so dropped Model: ABUN ~ YEAR + TEMP + DEPTHModel: ABUN ~ YEAR + TEMP + DEPTH

27 Scaled Survey Indices All surveysAll surveys

28 Scaled Survey Indices Southern surveysSouthern surveys

29 Scaled Survey Indices Northern surveysNorthern surveys

30 Standardized Index - All Surveys Used same data as during previous analyses, all years shownUsed same data as during previous analyses, all years shown Model: ABUN ~ YEAR + TEMP + SURVEYModel: ABUN ~ YEAR + TEMP + SURVEY

31 Standardized Index - All Surveys 1990 – 2012 shown1990 – 2012 shown

32 Conclusions A signal of increased abundance in latest years, though variable, was indicated throughout the analysisA signal of increased abundance in latest years, though variable, was indicated throughout the analysis The most notable and consistent signal is an increase in the last 2 years of data with the exception of VAThe most notable and consistent signal is an increase in the last 2 years of data with the exception of VA The data, especially data from NY north, corroborates the trends seen in the stock assessmentThe data, especially data from NY north, corroborates the trends seen in the stock assessment This information may add to the circumstantial case that abundance has continued to increase through time, and therefore cautious increases in allowed harvest may be warrantedThis information may add to the circumstantial case that abundance has continued to increase through time, and therefore cautious increases in allowed harvest may be warranted EThis would help to test the system and gather more information on the stability of the stock assessment EAn increase in harvest may help to decrease the high regulatory discard levels that are currently occurring in this fishery


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