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Tease apart unclassified groups of species

Source: vignettes/disaggregate.Rmd
disaggregate.Rmd

Little and winter skate species as well as silver and offshore hake species are often reported as unclassified in the commercial landings. The NEFSC bottom trawl survey is used to tease out the contribution of each species to the total of unclassified landings. The bottom trawl survey identifies and weighs all species caught. Estimates of the proportion of each species are estimated through time and space. These proportions are then applied to the landings data to result in estimates of species landed.

Skates

  • Skate species in the bottom trawl survey are identified with SVSPP codes = 22:28
  • The location of bottom trawl tows (both in SPRING and FALL) are assigned to statistical areas in which landings are reported.
  • The proportion caught (by biomass) by season is then applied to the commercial landings (SPPLIVWT) and value (SPPVALUE) for the unclassified skates (NESPP3 = 365) and assigned to little skate (NESPP3 = 366) or winter skate (NESPP3 = 367). The remained is left as unclassified.

Hakes

The same process is applied to the hake species

  • Offshore hake (SVSPP = 69) and silver hake (SVSPP = 72)
  • Commercial data base code for unclassified hakes (NESPP3 = 507). Resulting landings are assigned to offshore hake (NESPP3 = 508) and silver hake (NESPP3 = 509)