New Zealand Journal of Marine and Freshwater Research abstracts

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

STUART HANCHET*

Portobello Marine Laboratory University of Otago P. O. Box 8, Portobello Otago, New Zealand

Abstract The reproductive characteristics of the New Zealand population of Squalus acanthias Linnaeusare similar to thoseof northern hemisphere populati ons. 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.

Keywords reproduction; elasmobranch; Squalus acanthias; Otago; migration;reproductive behaviour

New Zealand Journal of Marine and Freshwater Research, 1988, Vol. 22: 537-549 Crown copyright 1988Received 12 October 1987; accepted 12 January 1988

PDF file of entire paper: medium quality (892K); (scanned from paper original: notes about this process)

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