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Technical Documentation, State of the Ecosystem Report

20 Inshore survey (Massachusetts)

Description: Massachusetts Division of Marine Fisheries Bottom Trawl Survey

Indicator category: Database pull with analysis

Found in: State of the Ecosystem - Mid-Atlantic (2019+), State of the Ecosystem - New England (2019+)

Contributor(s): Andrew Beet, Sean Lucey

Data steward: Andrew Beet

Points of contact: Andrew Beet

Public availability statement: Data are available upon request.

20.1 Methods

20.1.1 Data sources

Mass Inshore bottom trawl survey data sets were derived from raw survey data. Data from the Massachusetts Inshore Bottom Trawl Survey are stored on local servers at the Northeast Fisheries Science Center (Woods Hole, MA), and are also available upon request. More information about the Massachusetts Inshore Bottom Trawl Survey is available here.

20.1.2 Data extraction

Source data from the Massachusetts DMF Bottom Trawl Survey were pulled using the function survdat::get_mass_inshore_survey_data() form the R package survdat.

20.1.3 Data analysis

Biomass indices were provided as stratified mean biomass (kg tow-1). Time series of stratified mean biomass were calculated through the following procedure:

  1. All species catch weights were summed for each tow and for each feeding guild category.
  2. The average weight per tow, associated variances and standard deviation for each survey, region, stratum, and feeding guild was calculated.
  3. Stratified mean biomass was then calculated as the sum of the weighted averages of the strata, where the weight of a given stratum was the proportion of the survey area accounted for by that stratum.

These calculations followed those used to find stratified mean biomass by feeding guild in the NEFSC Bottom Trawl Survey and are described in greater detail in the Survey Data section.

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