Biological observations on sharks caught by sport fisherman of New South Wales

Abstract

Between 1979 and 1982, 523 sharks representing four families and 13 species were examined from sport fishing catches off New South Wales. Additional catch data were available from records of the Sydney Game Fishing Club extending from 1953 to 1979. The species composition of sharks caught changes through the year, probably as a result of seasonal variations in water temperature. Prionace glauca and Isurus oxyrinchus are most abundant in the catches during the cooler months from May to November. Galeocerdo cuvieri, Carcharhinus brevipinna, C. longimanus, C. falciformis, C. limbatus and Sphyrna lewini are taken principally during the warmer months from December to April. The sex ratio of P. glauca and Sphyrna zygaena changes through the year due to a seasonal influx of gravid females. At least six of the species examined give birth off New South Wales and, apart from C. falciformis, all of these appear to have restricted breeding seasons. P. glauca and S. zygaena feed mainly on cephalopods and to a lesser extent on fish, I. Oxyrinchus principally on fish, and G. cuvieri mostly on fish, birds, unidentified mammals and cephalopods.