Environmental Conservation

Report

Limited potential to recover from overfishing raises concerns for deep-sea sharks, rays and chimaeras

COLIN A. SIMPFENDORFERa1 c1 and PETER M. KYNEa2 p1

a1 School of Earth and Environmental Sciences, James Cook University, Townsville, Queensland 4811, Australia.

a2 School of Biomedical Sciences, University of Queensland, St. Lucia, Queensland 4072, Australia

SUMMARY

As global fishing effort increasingly expands into deeper water, concerns exist over the ability of deep-sea fishes to sustain fisheries. There is however little quantitative evidence to support these concerns for the deep-sea cartilaginous fishes (Chondrichthyes: sharks, rays and chimaeras). This paper compiled available life history data for this group to analyse their ability to rebound from population declines relative to continental shelf and pelagic species. Deep-sea cartilaginous fishes have rates of population increase that are on average less than half those of shelf and pelagic species, and include the lowest levels observed to date. Population doubling times indicate that once a stock has been depleted, it will take decades, and potentially centuries, before it will recover. Furthermore, population recovery rates decrease with increasing depth, suggesting species that occur deepest are those most vulnerable to fishing. These results provide the first assessment of the productivity of deep-sea chondrichthyans, highlighting that precautionary management of developing deep-sea fisheries is essential if stocks and biodiversity are to be maintained.

(Received June 30 2009)

(Accepted September 30 2009)

Correspondence

c1 Correspondence: Colin Simpfendorfer e-mail: colin.simpfendorfer@jcu.edu.au

p1 current address: Tropical Rivers and Coastal Knowledge, Charles Darwin University, Darwin, Northern Territory 0909, Australia