"The United States and several other countries have significantly reduced bycatch in their waters," she noted. "Slight modifications in fishing gear can mean the difference between life and death for dolphins."
Species on the bycatch priority list include the Irrawaddy dolphin. Globally threatened, the marine mammal has at least two populations that are listed as critically endangered by the IUCN.
The dolphin's last known haunt in the Philippines is Malamapaya Sound, where only around 77 individual dolphins remain. Study co-author Brian D. Smith, of the New York-based Wildlife Conservation Society, says the population's decline is almost certainly due to crab fishing.
Smith said a positive step would be to develop more efficient crab pots as an alternative to nets, which ensnare and kill Irrawaddy dolphins. He and his colleagues also recommend closing some Irrawaddy dolphin habitats to gillnet fishing.
In addition, data suggest that thousands of harbor porpoises are killed annually in the Black Sea by gillnets set for turbot, sturgeon, and dogfish.
In 2003 the International Whaling Commission indicated that existing fisheries regulations for the Black Sea were not being enforced. The WWF report recommends assisting Black Sea nations, such as Ukraine, to tackle illegal fishing.
In the case of Atlantic humpback dolphins, the report's authors have little idea how many of the animals remain or how many die as bycatch. The coastal species is found only in West Africa. Some Atlantic humpback dolphin populations are known only by a single specimen.
Lack of Data
In Ghana, West Africa, tens of thousands of coastal residents earn their livelihood from the sea. Because of this, researchers say, gillnet closures are unlikely. They add that little has been done to safeguard dolphins in the region, mainly because a lack of data has left regional governments unconvinced that stocks are severely depleted.
In other parts of the word, measures to reduce levels of cetacean bycatch are thought to be working. In U.S. waters, for example, gillnets are now prohibited in some coastal areas. Pingers (acoustic deterrents that warn or scare dolphins, porpoises, and whales away from fishing nets) are mandatory in other areas.
In European Union waters, the use of drift nets for tuna in the Atlantic and Mediterranean was banned in 2002. All other drift-netting will be phased out by 2008. Pingers are also becoming mandatory for all E.U. gillnet fisheries.
It's the fate of dolphins and porpoises in the developing world that most concerns conservationists, especially because these waters support the greatest number of cetacean species and the most at-risk populations. The WWF report says fisheries in the developing world "tend to be small-scale and decentralized, making assessment, monitoring and conservation intervention difficult."
Baragona, of WWF, says developing nations must recognize they have a problem and make change a priority. She also calls for better data on fisheries by these countries: "How many boats? What type of gear? What are they targeting? How much bycatch are they landing?" She adds that better enforcement of fishing regulations and increased monitoring of cetaceans is also needed in developing nations.
Baragona says that, around the world, fishing gear that traps marine mammals needs to be replaced.
"A more cutting edge approach is to use nets infused with barium sulfate, which makes them stiffer [and thus less likely to tangle] and easier [for marine mammals] to detect acoustically [for example, with sonar]," she said. This technology could possibly be "combined with materials that make the nets glow in the dark underwater, so the animals can see them," she added.
In April WWF awarded a prize for a fishing net design incorporating such dolphin-friendly features.
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