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Technical Documentation, State of the Ecosystem Report

31 Gray Seal Bycatch

Description: Gray Seal 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.

31.1 Methods

31.1.1 Data sources

Reported harbor porpoise bycatch estimates and potential biological removal levels can be found in publicly available documents; detailed in Marine Mammal Protection Stock Assessments. More detailed documentation as to the methods employed can be found in NOAA Fisheries Northeast Fisheries Science Center (NEFSC) Center Reference Documents (CRDs) found on the NEFSC publications page.

31.1.2 Data extraction

Annual gillnet bycatch estimates are documented in the CRDs. These feed into the Stock Assessment Reports which report both the annual bycatch estimate and the mean 5-year estimate.

31.1.3 Data analysis

Bycatch estimates as found in stock assessment reports were plotted along with confidence intervals. The confidence intervals were calculated from published CVs assuming a normal 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, Gray Seal.

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