Age, growth, and year-class strength of Goldeye rockfish Sebastes thompsoni in the coastal waters of the northern Japan Sea

Abstract

The age, growth, and year-class strength (YCS) of Sebastes thompsoni, a principal rockfish species supporting commercial fisheries along the Japan Sea coast, were examined using 11,089 specimens collected from coastal waters off the Aomori Prefecture, northern Japan, and a 14-year series (2011–2024) of fixed gillnet catch data. By applying the otolith cross-section method for age determination, we found that this species can attain ages exceeding 40 years, which is substantially older than previously established using the whole-otolith method. Sex-specific von Bertalanffy growth models revealed pronounced sexual dimorphism, with growth trajectories diverging after approximately 10 years and the asymptotic lengths of females exceeding those of males. Age-specific catch per unit effort (CPUE), standardised using gamma generalised linear mixed models, showed strong temporal continuity of year classes within the fishery. Linear mixed-effects modelling of age-specific CPUE identified pronounced variations in the YCS, with the 2014-year class emerging as exceptionally strong. These results revise the longevity and growth characteristics of S. thompsoni, demonstrate persistent cohort signals in the fishery, and provide an improved biological basis for future age-structured assessments and regional management of long-lived rockfish species.