Life history, distribution, and size structure of Pacific capelin in Prince William Sound and the northern Gulf of Alaska

Abstract

Seasonal distribution and size structure of larval, juvenile, and adult Pacific capelin, Mallotus villosus (Muller), were determined using data collected opportunistically during studies of larval fish and adult salmon and herring in Prince William Sound and the Gulf of Alaska. Larval and mainly juvenile capelin were widely distributed inside and west of Prince William Sound. Schools of adults were observed at the Prince William Sound-Gulf of Alaska interface in June, July, and August. Spawning was in June and July. Abundance of larval capelin offshore (>1 km) peaked in July, declining thereafter. Larvae appeared to move inshore, because nearshore (<1 km) abundance increased steadily from July to October. For part of the year, nursery areas are nearshore as capelin aged 0 and 1 dominated catches; most were caught within 400 m of the shore at bottom depths less than 100 m. Capelin catches were highest during May-June in three of the four years, and seasonal variability probably resulted from distributional changes inside bays and fjords, and/or variable growth and maturation rates. Recruiting events appeared to be annual, but annual catch rates declined from 1994 to 1997 as a consequence of changes in survival or distribution.