Sharks under threat

Forest and Bird, Volume 22, Issue 4, 1 November 1991, Page 2

Sharks under threat

Alan Tennyson

[\ EVERY OCEAN in the world sharks are coming under increasing pressure from expanding commercial fisheries. About 400 species of shark are known, ranging from the giant 12m planktonfeeding whale shark to tiny 20cm deepwater species. Only about twenty species are fished commercially and little is known of their biology. Earlier this year, a conference on shark conservation was held in Sydney and attended by thirty three international delegates and 130 shark enthusiasts. The conference highlighted the vulnerability of sharks to overfishing. Most sharks are long-lived (12-70 years), slow-growing, and produce relatively small numbers of young each year. Specific recommendations to assist the conservation of sharks were agreed to by the conference. If adopted in New Zealand several changes to fisheries management would be required: ¢ Known shark nursery grounds would be closed to fishing — a conservation measure of particular importance for heavily exploited inshore species, such as school shark and rig. e The practice of "finning" sharks would be outlawed and it would be a require-

ment for all sharks to be brought in and sold with fins intact. "Finning" is commonly carried out by Asian tuna longliners who catch more than one hundred thousand sharks in New Zealand waters each year. Quotas would be set and fisheries management plans established for all shark species. Currently the catch of only three species — school shark, rig and elephant fish — is controlled by quotas in New Zealand waters. International quotas would be needed for many wideranging pelagic species, such as blue

and mako sharks. More than two million blue sharks are killed each year in the North Pacific by drift nets set for squid. ¢ A minimum size for big game fish would be imposed so that immature sharks would be returned to the sea. Sharks are a vital and fascinating part of the marine ecosystem. They are top-level predators, and the decline in their numbers may be adversely affecting the whole marine ecosystem. g&