Leading scientists rank endangered dolphins, porpoises most in need of immediate action
Accidental capture in fishing nets pushes several species to the brink
Leading marine scientists for the first time have assessed dolphin and porpoise populations around the world which are severely threatened by entanglement in fishing gear and recommended nine urgent priorities for action in a report commissioned by the World Wildlife Fund. These nine projects highlight species threatened by bycatch that will most likely benefit from immediate action and will continue to languish without intervention.
The list of dolphins and porpoises that could recover if changes to fishing methods and other conservation efforts are made includes harbor porpoises in the Black Sea, where thousands of porpoises are killed each year; Atlantic humpback dolphins off the coast of west Africa; and franciscana dolphins in South America. Most of the species on the list are threatened by the widespread use of one type of fishing gear – gillnets. These nets are difficult for dolphins and porpoises to spot visually or detect with their sonar, so they may become tangled in the netting or in the ropes attached to the nets.
"Almost 1,000 whales, dolphins and porpoises die every day in nets and fishing gear. Some species are being pushed to the brink of extinction," said Karen Baragona of WWFs species conservation program. "We developed this ranking to help governments and aid agencies target their investments for the best return."
The report will be submitted to the International Whaling Commission (IWC) at its annual meeting next week in South Korea. The scientific committee of the IWC includes many of the worlds leading marine scientists, who last year endorsed the methodology of the WWF report.
The U.S. Commission on Ocean Policy last year noted that bycatch is the greatest threat globally to whales, dolphins and porpoises, known scientifically as cetaceans. Bycatch is the accidental capture in fishing gear of species--including cetaceans--that fishermen do not intend to catch. Because cetaceans need to come to the surface to breathe, if they are trapped underwater in fishing nets, they die. In 2003, researchers estimated that more than 300,000 cetaceans are killed in fishing gear each year in the worlds oceans.
"Rather than simply identifying the species or populations at greatest risk or the geographical locations where the bycatch problem is most severe, the group was asked to emphasize opportunities, such as situations where the prospects for successful intervention appeared especially good," said Randall Reeves, lead author of the report and the chairman of the IUCN Species Survival Commissions Cetacean Specialist Group. "Its crucial to give guidance to agencies and organizations on how they should invest their resources for bycatch mitigation."
Between 1993 and 2003, fisheries in the United States introduced changes that reduced cetacean bycatch to one-third of its previous levels. But so far little of this success has been transferred to other countries, and in much of the rest of the world, progress on bycatch mitigation has been slow or nonexistent.
"These accidental deaths can be significantly reduced, often with very simple, low-cost solutions. The United States and several other countries have significantly reduced bycatch in their waters. Slight modifications in fishing gear can mean the difference between life of death for dolphins," said Baragona. "But for many of these threatened dolphins and porpoises, we need to act now before its too late."
In April, WWFs International Smart Gear Competition awarded a prize to a promising gillnet design concept using glowing ropes and stiffer nets that may help cetaceans see gillnets in order to avoid them and to escape if they do accidentally swim into the net.
Species and populations designated in the report as among the top priorities for investment of resources are:
- Irrawaddy dolphins in the crab net/trap fishery in Malampaya Sound, Philippines
- Irrawaddy dolphins in gillnets in the Mekong, Mahakam and Ayeyarwady rivers and in Chilka and Songkhla lakes, Southeast Asia
- Indo-Pacific humpback dolphins and Indo-Pacific bottlenose dolphins in drift and bottom-set gillnets on the south coast of Zanzibar (Tanzania)
- Harbor porpoises in coastal gillnets in the Black Sea
- Spinner dolphins and Frasers dolphins in large-mesh driftnets and purse seines in the Philippines
- Atlantic humpback dolphins in coastal gillnets in the northern Gulf of Guinea (Ghana, Togo)
- Burmeisters porpoises in artisanal gillnets in Peru
- Franciscana dolphins in coastal gillnets in Argentina, Uruguay, and Brazil
- Commersons dolphins in coastal gillnets and midwater trawls in Argentina
Sarah Janicke | EurekAlert!