Reproductive biology of Squalus acanthias from the east coast, South Island, New Zealand

Abstract

Abstract The reproductive characteristics of the New Zealand population of Squalus acanthias Linnaeus are similar to those of northern hemisphere populations. Young are born at a length of 18–30 cm (mean 24 cm) from March to September, after a two‐year gestation period. Shortly afterovulation, females move inshore where they spend the first year of pregnancy in shallow water (50 m depth). During the second year the majority migrate back to deep water (200–300 m) where parturition, mating, and ovulation take place. Litter size and length of young at birth increase linearly with parent length. Number of young ranges from 1 to 16. On average, males mature at 58 cm; females mature at 71.5 cm off Otago, but at 74.5 cm off Banks Peninsula and Kaikoura. Maximum observed lengths were 111 cm for females and 90 cm for males. Reproductive failures were high compared to northern hemisphere populations, and comprised addled eggs, females resting between pregnancies, and non‐developing uterine eggs.