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Technical Documentation, State of the Ecosystem Report

28 Harbor Porpoise Bycatch

Description: Harbor Porpoise Bycatch Indicator

Found in: State of the Ecosystem - Gulf of Maine & Georges Bank (2018+), State of the Ecosystem - Mid-Atlantic (2018+)

Indicator category: Synthesis of published information; Published methods

Contributor(s): Kristin Precoda, Christopher D. Orphanides, Debra Palka

Data steward: Debra Palka

Point of contact: Debra Palka

Public availability statement: Source data are available in public stock assessment reports.

28.1 Methods

28.1.1 Data sources

Bycatch estimates and potential biological removal levels are reported in the publicly available Marine Mammal Stock Assessment reports. More descriptions on data sources, processing and analyses are found in Northeast Fisheries Science Center (NEFSC) Center Reference Documents (CRDs) and journal papers. The data to calculate the bycatch estimate comes from observer program databases and fishing effort databases.

28.1.2 Data extraction

Annual and 5-year averaged bycatch estimates are documented in Center Reference Documents (CRD). The potential biological removal values are extracted from the Stock Assessment Reports.

28.1.3 Data analysis

Bycatch estimates and their associated coefficients of variation are documented in the CRDs, then reported in the Marine Mammal Stock Assessment Reports. Annual estimates from all fisheries as reported in the Marine Mammal Stock Assessment Reports are summed together and the CV of the sum is calculated using the delta method. The 95% confidence intervals are then calculated from the sums and associated CVs assuming a lognormal distribution. (\(\sigma = \mu CV\); \(CI = \bar{x} \pm \sigma * 1.96\)).

Data were analyzed and formatted for inclusion in the ecodata R package using the R code found here, Harbor Porpoise.

catalog link https://noaa-edab.github.io/catalog/harborporpoise.html