Assemblage of deep-sea sharks on Chatham Rise, New Zealand

The distribution and abundance of deep-sea sharks on Chatham Rise, New Zealand, are described. Sharks were collected as bycatch in two deep-water trawl fisheries at a total of 390 stations, which ranged in depth from 740 to 1503 m. Sixteen species of shark were caught; Deania calcea, Centroscymnus crepidater, Etmopterus granulosus, and Centroscymnus owstoni accounted for the largest portion of the shark catch. Species that would provide the highest yield of commercially important liver lipids were not abundant in trawls. All sharks combined formed only 4.2% of overall biomass captured in trawls. Depth is a major determinant of the composition of the shark assemblage; both density of sharks (kg/km(2)) and species diversity were inversely proportional to depth. Distributional patterns of the shark community varied with location on Chatham Rise, and species composition of the shark catch varied with the species of teleost targeted in deep-water trawls.