Catch and life history parameters of pelagic sharks in the Northwest Pacific.

Abstract

Annual landings (whole weight) of sharks at Nanfangao and Chengkung fish markets, eastern Taiwan fluctuated from 4,762 MT in 2001 to 4,794 MT in 2010 with a mean of 5,669 MT during this period. Blue shark was the dominant shark species and it consisted of 44.54% in weight of shark landing. The scalloped hammerhead and shortfin mako sharks were the other major species which comprised 9.87% and 9.42% in weight of shark landings, respectively. The life history parameters including age, growth and reproductive biology of 11 species of pelagic sharks in the Northwest Pacific were presented. Most age determinations were solely based on vertebral band counting only few were coupled with length-frequency analysis. Of these, 8 species are viviparous, and 3 species are ovoviviparous; the litter size ranges from 2 for pelagic and bigeye thresher shark to 30 for smooth hammerhead shark. The stock assessments of the pelagic thresher and shortfin mako suggested these stocks are overexploited.