The length based multispecies model (Hydra) requires annual indices of biomass and abundance by species size class. The NEFSC spring and fall bottom trawl surveys collect the information required to obtain estimates of these indices
Each tow/haul during the bottom trawl survey collects the total weight of each fish species caught. A sample of the haul is then taken and each fish in this sample is identified, lengthed (to the nearest cm) and weighed.
The R package survdat is
used to read in the survey data and provide estimates of swept area
biomass and abundance on the Georges Bank footprint. The survey strata
that define Georges
Bank are 1090, 1130:1210, 1230, 1250, 3460, 3480, 3490,
3520:3550.
## Linking to GEOS 3.10.2, GDAL 3.4.1, PROJ 8.2.1; sf_use_s2() is TRUE
suppressMessages(out <- create_real_survey_lennumcomp(convertKGtoMT=T))
