Spatial, seasonal and biological analysis of sharks caught in the New South Wales protective beach meshing programme

Abstract

Data for the catches of sharks at each beach meshed in New South Wales are presented for the period from October 1972 to December 1990. High catch rates of sharks were observed at a number of these beaches. Comparison of the catches of sharks at each beach by means of hierarchical clustering and nonmetric multidimensional scaling revealed regional associations as well as some unusual relationships. Beaches at either end of each netted region (i.e. Newcastle, Sydney or Wollongong) tended to have higher catches than did beaches in the centre of each region. Hammerhead sharks (Sphyrna spp.) had significantly higher catch rates on long open beaches. Significantly higher catches of whaler (Carcharhinus spp.), white (Carcharodon carcharias), and tiger (Galeocerdo cuvier) sharks occurred when deeper water was closer to the beach. Limited biological and seasonal data are also presented for the 11 species or species groups: Sphyrna spp., Carcharhinus spp., Squatina austmlis, Heterodontus spp., Carcharodon carcharias, Galeocerdo cuvier, Carcharias taurus, Notorynchus cepedianus, Alopias spp., Isurus oxyrinchus and Orectolobus spp.