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Bycatch threatens marine mammals, but new protections hold promise for Mexican vaquita

Marine mammal scientists report on species in peril at San Francisco science conference

NOAA Fisheries West Coast Region

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IMAGE: Vaquita are among the most endangered marine mammals on earth, with fewer than 100 remaining. view more

Credit: Paula Olson

Gillnetting around the world is ensnaring hundreds of thousands of small cetaceans every year, threatening several species of dolphins and porpoises with extinction, according to research presented at the Society of Marine Mammalogy's 21st biennial conference in San Francisco this week.

But there is one bright spot in the Gulf of California, where Mexican authorities earlier this year instituted an emergency two-year ban on gillnetting to help save the critically endangered vaquita, now the rarest marine mammal species on the planet. Fewer than 100 vaquita remain, scientists speaking at the conference said.

On Monday the Society of Marine Mammalogy will recognize Mexican officials including President Enrique Peña Nieto, Secretary of Environment and Natural Resources, Rafael Pacchiano, top Mexican biologists, economists and fishermen with its first-ever Conservation Merit Prize. The prize will recognize the recipients for their determination to save the vaquita and help local fishermen transition to fishing gear friendly to the small porpoise whose entire population lives in the northern Gulf of California, Mexico. Secretary Pacchiano will be present to accept the award on behalf of the Mexican government.

Scientists at the conference said there is a great need for a success story demonstrating that sustainable fishing can coexist with marine mammals, and they hope the vaquita can provide it.

"This is the first large-scale gillnet ban to save a species from extinction, and includes provisions for the development of alternative fishing gear to replace gillnets," said Barbara Taylor, chair of the Society's Conservation Committee, who recently returned from more than two months aboard a research ship surveying the northern Gulf of California for vaquita. "We have great hope that this will be the model that shows the world it is truly possible to bring a species back from the brink of extinction."

The award presentation will provide some of the conference's most hopeful news for marine mammals in peril from threats ranging from climate change to chemical contaminants. Many other threatened species from polar bears to manatees will also be the focus of new studies and research presented at the conference, the largest gathering of marine mammal researchers in the world.

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Other new studies to be reported at the conference include:

  • Declining reproduction of polar bears in western Hudson Bay, Canada, where the bears mainly feed on ringed seals they hunt on sea ice during winter. During summer, they rely mainly on fat stores to sustain them. Progressively earlier sea ice breakup through the 1990s and early 2000s left the bears less time to hunt. Although the sea ice breakup has not trended earlier in the last decade, female polar bears are continuing to give birth to fewer litters and fewer cubs, at longer intervals.

  • Inexpensive methods may be available to reduce the bycatch of marine mammals in non-mechanized fisheries in developing nations, which account for more than 95 percent of fishers around the world, according to research presented at the conference. For instance, one approach in Zanzibar, East Africa, employs recycled glass and plastic bottles with bolts inside that help prevent marine mammals from becoming entangled in floating gillnets, at little or no cost.

  • Scientists examined the earplug of a bowhead whale from the Arctic for clues about its exposure to chemical contaminants and stress. For example, signatures of the stress hormone cortisol may provide clues about stress from environmental noise such as ship traffic. Reduced levels of contaminants following pregnancies also suggest the whale transferred many of the contaminants to its calves when they were born.

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