Size and spatial distribution of the blue shark, Prionace glauca, caught by the Taiwanese large-scale longline fishery in the North Pacific Ocean

Abstract

The size and spatial distribution of the blue shark, Prionace glauca, were described based on 5,897 specimens, that were collected by scientific observers on-board the Taiwanese large-scale tuna longline vessels in the North Pacific between June 2004 and December 2020. Size segregation was found, and the mean size of blue sharks in area B (0-25°N) was significantly smaller than that in area A (north of 25°N). No significant sex segregation was found. Males predominated in the size range of 170-280 cm and 170-200 cm TL in area A and B, respectively.