Catch, size and distribution pattern of the blue shark caught by the Taiwanese small-scale longline fishery in the North Pacific

Abstract

This study presented the catch, size, and distribution pattern of the blue shark by the Taiwanese small-scale tuna longline (STLL) fishery in the North Pacific. Catch estimated was based on the landing data from the three major fishing ports for STLL fishery. The estimated annual catch of blue sharks by the Taiwanese small-scale tuna longline fisheries ranged from 6,983 MT in 2013 to 16,082 MT in 2009, with a mean of 11,685 MT in 2001-2020. The mean sizes were estimated to be 183 cm and 185 cm FL for females and males, respectively. Juvenile females were found in the tropical and subtropical area but adults were more often found in the temperate area. The smallest mean sizes for both sexes were found in season 2. The sex ratio was significantly different from 0.5 for every season except season 4.