Updated estimation of catch and CPUE of the blue shark in Taiwanese large-scale longline fishery.

Abstract

In the present study, the blue shark catch and effort data from observers’ records of Taiwanese large longline fishing vessels operating in the North Pacific Ocean from 2004-2011 were analyzed. Due to the large percentage of zero shark catch, the catch per unit effort (CPUE) of blue shark, as the number of fish caught per 1,000 hooks, was standardized by zero inflated negative binomial model. The analysis of standardized CPUE showed a stable increasing trend for blue sharks. 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.