Overfishing Pushes Open Ocean Sharks Towards Extinction

The first study to determine the global conservation status of 64 species of open ocean sharks and rays reveals that 32 percent are threatened, primarily due to overfishing, and 52 percent of the shark species taken in high-seas fisheries are threatened.

"The vulnerability and lengthy migrations of most open ocean sharks call for coordinated, international conservation plans, says Sonja Fordham, deputy chair of the IUCN Shark Specialist Group and policy director for the Shark Alliance.

"Our report documents serious overfishing of these species, in national and international waters, and demonstrates a clear need for immediate action on a global scale," Fordham said.

Hammerhead sharks in the waters of the Galapagos Islands (Photo by Water Planet)

In most cases, open ocean shark catches are unregulated or unsustainable, the study finds. Twenty-four percent of the species examined are categorized as Near Threatened, while information is insufficient to assess another 25 percent.

Many open ocean sharks are taken in the high seas tuna and swordfish fisheries. Once considered only incidental bycatch, these species are increasingly targeted due to new markets for shark meat and high demand for their valuable fins, used in the Asian delicacy shark fin soup.

To source this demand, the fins are often cut off sharks and the rest of the body is thrown back in the water, a process known as finning.

Finning bans have been adopted for most international waters, but lenient enforcement standards hamper their effectiveness, the shark specialists say.

Sharks are particularly sensitive to overfishing due to their tendency to take many years to mature and have relatively few young.

The report is based partially on an IUCN Shark Specialist Group workshop funded by the Lenfest Ocean Program. Fifteen experts from government agencies, universities, non-governmental organizations, and institutions around the world took part.

This and other regional workshops have contributed to the development of the Shark Specialist Group's Global Shark Red List Assessment, supported by Conservation International and the New Hampshire Charitable Foundation.

"The completion of this global assessment of pelagic sharks and rays will provide an important baseline for monitoring the status of these keystone species in our oceans," says Roger McManus, vice president for marine programs at Conservation International.

The IUCN Shark Specialist Group calls on governments to set catch limits for sharks and rays based on scientific advice and the precautionary approach. It further urges governments to fully protect Critically Endangered and Endangered species of sharks and rays, ensure an end to shark finning and improve the monitoring of fisheries taking sharks and rays.

Governments should invest in shark and ray research and population assessment, minimize incidental bycatch of sharks and rays, employ wildlife treaties to complement fisheries management and facilitate cooperation among countries to conserve shared populations, according to the group.

Great white shark, Carcharodon carcharias, South Australia (Photo by Homezone Testing)

The report comes days before Spain hosts an international summit of fishery managers responsible for high seas tuna fisheries in which sharks are taken without limit.

It coincides with an international group of scientists meeting this week in Denmark to formulate management advice for Atlantic porbeagle sharks.

Porbeagle sharks, Lamna nasus, are classified as globally Vulnerable, but are considered Critically Endangered in the Northeast Atlantic and and Endangered in the Northwest Atlantic.

IUCN experts classify Great Hammerhead, Sphyrna mokarran, and Scalloped Hammerhead, Sphyrna lewini, sharks, as well as Giant Devil Rays, Mobula mobular, as globally Endangered.

Smooth Hammerheads, Sphyrna zygaena, Great White, Carcharodon carcharias, Basking, Cetorhinus maximus, and Oceanic Whitetip, Carcharhinus longimanus, sharks are classed as globally Vulnerable to extinction, along with two species of Makos, Isurus spp., and three species of Threshers, Alopias spp.

The Blue Shark, Prionace glauca, the world's most abundant and heavily fished open ocean shark, is classified as Near Threatened.

The IUCN Shark Specialist Group is a network of 180 experts from 90 countries who are involved in research, fisheries management, marine conservation or policy development and implementation for sharks and their relatives; the skates, rays and chimaeras. The group is responsible for assessing the conservation status of the more than 1,000 species.

The group aims to promote the long-term conservation of these species, effective management of their fisheries and habitats and, where necessary, the recovery of their populations.

Copyright Environment News Service, ENS, 2009. All rights reserved.