The Blue Shark is oceanic and pelagic, found from the surface to depths of 1000 m (Weigmann 2016). It occasionally occurs close inshore when the continental shelf is narrow. This species reaches a maximum size of about 380 cm total length (TL). About 50% of males in the Atlantic are sexually mature by 218 cm, although some may reach maturity as small as 182 cm TL. Females are sub-adult from 173-221 cm TL and fully mature from 221 cm TL (Pratt 1979), although pregnant specimens as small as 183 cm TL have been recorded from the eastern Pacific (Williams 1977).Blue Sharks are placentally viviparous, producing litters averaging about 35 pups (maximum recorded 135) after a gestation period of 9-12 months. At birth, pups measure 35-50 cm TL. Reproduction has been reported as seasonal in most areas, with the young often born in spring or summer (Pratt 1979, Stevens 1984, Nakano 1994) although the periods of ovulation and parturition may be extended (Hazin et al. 1994). Ageing studies suggest a longevity of about 20 years with males maturing at 4-6 and females at 5-7 years (Stevens 1975, Cailliet et al. 1983, Nakano 1994). Smith et al. (1998) estimated the intrinsic rate of population increase at MSY to be 0.061.Generation length is estimated to be 10.5 years based on study of Blue Shark in the Northwest Pacific by Nakano (1994).