Feasibility of a bottom trawl survey for three slope groundfish species in Canadian waters / Paul J. Starr and Carl Schwarz. : Fs70-1/2000-156E-PDF

The feasibility for conducting research surveys using commercial bottom trawl gear targeted at three slope groundfish species located in the Pacific coast of Canada is presented. The objectives of such a survey are to generate comparable indices of population size over time which can be used as inputs into population assessment models for each of the three species. This feasibility analysis is based on the calculation of the variability in catch per hour for each species from commercial catch and effort data to determine the amount of stratification by depth and the number of tows required in each stratum to achieve a target level of precision. Of the three target species, longspine thornyheads appeared to be the least variable in commercial CPUEs and hence required the fewest tows to monitor the population. Shortspine thornyheads were of intermediate variability and Pacific Ocean perch were highly variable. Pacific ocean perch have a completely separate spatial distribution from the two thornyhead species and can be monitored independently of the other two species.

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