Research Document - 2006/073

A review of redbanded rockfish (Sebastes babcocki) along the Pacific coast of Canada: biology, distribution, and abundance trends

By Haigh, R., and P. Starr

Abstract

We summarise the available information on a data-limited species, redbanded rockfish Sebastes babcocki. Specifically, this paper reviews the current data on the biology, distribution, and abundance trends. This species has a mean weight of 1.337 kg/fish. Allometric growth shows no difference between the sexes; however, mature females achieve a larger size than males of equal age. With an estimated age-of-50%-maturity at 11.5 years, and an assumed natural mortality rate of 0.035, generation time is roughly 40 years. Model estimates of total mortality rate for the years 1997/98 range from 0.04 to 0.07, with no variation among areas of purported light and heavy exploitation. According to commercial trawl records, redbanded rockfish prefer depths between 132 m and 421 m. Using this preference, a bathymetric analysis estimates the potential extent of occurrence at 47,877 km² and the area of occupancy at 27,432 km². However, based on trawl observations alone, the area of occupancy could easily equal 33,200 km². Within its habitat, the two dominant concurrent species are Pacific ocean perch Sebastes alutus and arrowtooth flounder Atheresthes stomias. Total removal of redbanded rockfish from BC coastal waters by the commercial fleet from 1996 to Sep 2005 equals approximately 3 million fish. Survey indices of abundance are currently not useful for assessing redbanded rockfish population trends. The Hecate Strait assemblage and WCVI shrimp surveys are too shallow; the US triennial survey too uncertain, and the QCS synoptic survey too short. The commercial trawl CPUE indices show a slightly increasing trend in 3CD and slightly declining trends in 5AB and 5CD. The commercial longline CPUE indices show very strong trends, but these probably reflect fluctuations in catch activity rather than changes in fish population density.

Complete document (PDF, 2878 KB)

Accessibility Notice

This document is available in PDF format. If the document is not accessible to you, please contact the Secretariat to obtain another appropriate format, such as regular print, large print, Braille or audio version.