data related issues

[andybeet]

After chatting to Bart and Adam (GMRI) there are several issues that need addressing:

• The average swept area of the trawl. Default value is the swept area of a standard NOAA Ship Albatross IV tow. (a = 0.0384). Document why?
• Mostly < year 2000. ABUNDANCE (EXPCATCHNUM) >0 with BIOMASS (EXPCATCHWT)= 0. why? In particular 1980 Dogfish (SVSPP=15)
  a$survdat |> dplyr::filter(SVSPP==15, YEAR == 1980, BIOMASS < 0.01, ABUNDANCE > 0) |> dplyr::select(CRUISE6,STATION,STRATUM,ABUNDANCE,LENGTH,NUMLEN,BIOMASS)
  
• Also cases where ABUNDANCE = 0, BIOMASS > 0. Related issue
• Are conversions applied to numbers at length AND biomass? Related issue and issue
• How have survey methods changed over time? In particular frequency of length samples. Now all species get lengthed, when did this start. History?
• length-weight relationship for ALL species. Wigley et all only 60+ species.