Interannual variability in stock abundance of the neon flying squid, <i>Ommastrephes bartramii</i>, in the North Pacific Ocean during 1979–1998: impact of driftnet fishing and oceanographic conditions

Abstract

Variability in catch‐per‐unit‐effort (CPUE) was examined for the autumn cohort of Ommastrephes bartramii collected with research driftnets during 1979–1998 along five longitudinal transects passing through the Subarctic, Transitional and Subtropical Domains in the North Pacific. CPUE was generally low during the period of intensive commercial driftnet fishing (1980–1992) and increased following the 1992 moratorium on the use of large‐scale driftnets. However, CPUE levels were low for the cohorts hatched in 1992 and 1996 (captured in subsequent years owing to a one‐year life of O. bartramii ) that experienced low sea surface temperatures from hatching to recruitment. Among similar‐aged squid collected from 180° and 179°30′W in June, mantle lengths were significantly greater in 1997 than during 1995–96. These findings suggest that the driftnet fishery and sea surface temperatures from hatching to recruitment strongly affected stock abundance and possibly growth.