Bycatch of rockfish and other species in British Columbia spot prawn traps: Preliminary assessment using research traps

Abstract

Abstract The spot prawn (Pandalus platyceros) trap fishery in British Columbia is endorsed by conservation organizations owing to the assumption of minimal bycatch. However, reported capture of juvenile rockfish (Sebastes spp.) in prawn traps has raised concern due to declines in abundance of many rockfish stocks. We document the bycatch observed in a 10-year (1999–2008) fishery-independent research survey that employed traps that are similar to the traps used in the commercial spot prawn fishery. Research traps produced 0.16–0.20 kg of non-target catch per kg of spot prawn catch, with bycatch consisting mainly of a variety of molluscs, non-target crustaceans, echinoderms, and fish. The overall rate of rockfish catch was low—0.015 rockfish per trap. The annual rate of rockfish bycatch has increased since 2004, to 0.039 rockfish per trap in 2008, while catch rates of other species have remained relatively constant. Our results confirm that spot prawn traps produce a low amount of bycatch by weight. However, they also suggest that rockfish mortality due to prawn trapping should be quantified in the commercial prawn fishery to determine how this source of mortality may affect rockfish stocks. Furthermore, research into bycatch reduction technology to improve trap selectivity, and thus reduce rockfish bycatch, would be desirable.