Status of adult chum salmon capture for hatchery broodstock in rivers on the Japan Sea side of northern Honshu, Japan

Abstract

To improve the precision of chum salmon stock assessments, this study investigated the status of adult chum salmon capture for hatchery broodstock in rivers on the Japan Sea side of northern Honshu, Japan. Hatchery weir, which exhibits relatively low annual shifts in fishing effort, and other fishing techniques such as casting net and hook fishing, which exhibit relatively large annual variations in fishing effort, were applied on 65% and 35% of the 66 rivers, respectively. The proportions of chum salmon caught in rivers using other fishing techniques from 2014-2016 were low (12.4%-15.7%) but varied considerably across the prefectures (0%-30.4%). The number of users of other fishing techniques decreased considerably in the studied rivers. The results imply that the stock levels estimated based on the catch in the rivers where other fishing techniques were used could be underestimated.