37 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, Debra Palka

Data steward: Debra Palka debra.palka@noaa.gov

Point of contact: Debra Palka debra.palka@noaa.gov

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

37.1 Methods

37.1.1 Data sources

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

37.1.2 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.

37.1.3 Data analysis

Annual estimates from all fisheries as reported in the CRDs 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. LCI = estimate / exp[qnorm(0.975) * sqrt(log(1+CV²))] UCI = estimate * exp[qnorm(0.975) * sqrt(log(1+CV²))]

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