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

Ancillary Indices of Abundance for Ancillary Indices of Abundance for Black Sea BassBlack Sea Bass

Working towards healthy, self-sustaining populations Working towards healthy, self-sustaining populations for all Atlantic coast fish species or successful for all Atlantic coast fish species or successful

restoration well in progress by 2015restoration well in progress by 2015

OverviewOverview

• The goal of the following presentation is to provide the The goal of the following presentation is to provide the SSC with information that they did not have during SSC with information that they did not have during consideration of the black sea bass stock assessmentconsideration of the black sea bass stock assessment

• The point is not to second guess previous decisions but The point is not to second guess previous decisions but to supplement the existing information to supplement the existing information

• This may allow for a case to be made to allow modest This may allow for a case to be made to allow modest

increases in harvest in this fisheryincreases in harvest in this fishery

Data TreatmentData Treatment

• Raw data from fishery independent trawl Raw data from fishery independent trawl surveys conducted by the Atlantic Coastal states surveys conducted by the Atlantic Coastal states was gatheredwas gathered

• The data were analyzed in a consistent fashion to The data were analyzed in a consistent fashion to provide some standardization between the provide some standardization between the different surveysdifferent surveys

• The surveys range throughout the biological The surveys range throughout the biological range of black sea bassrange of black sea bass

Data TreatmentData Treatment• Black sea bass abundance (# fish) information was used from each Black sea bass abundance (# fish) information was used from each

datasetdataset

• A consistent set of metrics were examinedA consistent set of metrics were examined The metrics chosen were ones that were consistent amongst datasetsThe 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 To account for the zero inflation, the datasets were pivoted against the various metricsvarious metrics Data rows were dropped in ranges or categories of the metric where Data rows were dropped in ranges or categories of the metric where

there were less than 5 fish for the entire time seriesthere 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

Data TreatmentData Treatment• It was found that the distributions in each survey It was found that the distributions in each survey

followed a negative binomial distributionfollowed a negative binomial distribution

• A negative binomial generalized linear model was A negative binomial generalized linear model was performed on the datasetsperformed on the datasets

• Full models were run and then non significant variables Full models were run and then non significant variables were removed, the simplified model was rerun were removed, the simplified model was rerun

• In each case, if additional modifications to the dataset In each case, if additional modifications to the dataset were performed, it is noted with a justificationwere performed, it is noted with a justification

VIMS Trawl SurveyVIMS Trawl Survey

• Data distributionData distribution

VIMS Trawl SurveyVIMS Trawl Survey

• Data distribution – zeroes removedData distribution – zeroes removed

VIMS Trawl SurveyVIMS 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

New Jersey Trawl SurveyNew Jersey Trawl Survey


New Jersey Trawl SurveyNew Jersey Trawl Survey

• Data distribution – zeroes removed and abundance truncatedData distribution – zeroes removed and abundance truncated

New Jersey Trawl SurveyNew 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

NEAMAP Trawl SurveyNEAMAP Trawl Survey


NEAMAP Trawl SurveyNEAMAP Trawl Survey

• Data distribution – zeroes removed and abundance truncatedData distribution – zeroes removed and abundance truncated

NEAMAP Trawl SurveyNEAMAP 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

NY Peconic Bay Trawl NY Peconic Bay Trawl SurveySurvey





• 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

Long Island Sound Trawl Long Island Sound Trawl SurveySurvey





• 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

Rhode Island Trawl Rhode Island Trawl SurveySurvey





• 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

MA Inshore Trawl SurveyMA 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

Scaled Survey IndicesScaled Survey Indices

• All surveysAll surveys


• Southern surveysSouthern surveys


• Northern surveysNorthern surveys

Standardized Index - All Standardized Index - All SurveysSurveys

• 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

Standardized Index - All Standardized Index - All SurveysSurveys

• 1990 – 2012 shown1990 – 2012 shown

ConclusionsConclusions• A signal of increased abundance in latest years, though variable, was A signal of increased abundance in latest years, though variable, was

indicated throughout the analysisindicated throughout the analysis

• The most notable and consistent signal is an increase in the last 2 years of The most notable and consistent signal is an increase in the last 2 years of data with the exception of VAdata with the exception of VA

• The data, especially data from NY north, corroborates the trends seen in The data, especially data from NY north, corroborates the trends seen in the stock assessmentthe stock assessment

• This information may add to the circumstantial case that abundance has This information may add to the circumstantial case that abundance has continued to increase through time, and therefore cautious increases in continued to increase through time, and therefore cautious increases in allowed harvest may be warrantedallowed harvest may be warranted This would help to test the system and gather more information on the stability of This would help to test the system and gather more information on the stability of

the stock assessmentthe stock assessment An increase in harvest may help to decrease the high regulatory discard levels that An increase in harvest may help to decrease the high regulatory discard levels that

are currently occurring in this fisheryare currently occurring in this fishery

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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