Reproductive Patterns of Pacific Ocean Perch (Sebastodes alutus) off Washington and British Columbia and their Relation to Bathymetric Distribution and Seasonal Abundance

Abstract

Females of the ovoviviparous species Sebastodes alutus release their larvae in March in the Washington–British Columbia area. Male maturity data from Queen Charlotte Sound indicated that males probably inseminate females in September or October. Examination of the annual bathymetric cycle in three major commercial trawling areas showed that mating and insemination occur while Pacific ocean perch are moving to deep water from the shallow-water regions inhabited in summer and that females release their larvae while in the deepest part of their bathymetric range.Total 1955 through 1965 catch by month, and 11-year mean monthly catch rates were used to indicate relative seasonal abundance on major fishing grounds. Where deepwater regions were trawled, these indices showed a spring maximum associated with the March spawning period. In all areas studied there was a midsummer slump in catch and catch rate, and an October maximum occurring during the suggested mating period.