Catch and standardized CPUE of the blue shark by Taiwanese large-scale longline fishery in the North Pacific Ocean

Abstract

In the present study, the blue shark catch and effort data from observers’records of Taiwanese large-scale longline fleets operating in the North Pacific Ocean from 2004-2010 were analyzed. Due to the large percentages of zero shark catch, the catch per unit effort (CPUE), the number of sharks caught per 1,000 hooks, was standardized by the zero inflated negative binomial model. The standardized CPUE showed a stable increasing trend for blue sharks during the time period. The results suggested that the blue shark stock in the North Pacific Ocean seems at the level of optimum utilization. The results in this study are preliminary and further investigation is needed.