Preserving 4 Percent of the Ocean Could Protect Most Marine Mammal Species

Of the 129 species of marine mammals on Earth, including seals, dolphins and polar bears, approximately one-quarter are facing extinction

Preserving just 4 percent of the ocean could protect crucial habitat for the vast majority of marine mammal species, from sea otters to blue whales, according to researchers at Stanford University and the National Autonomous University of Mexico.

Their findings were published in the Aug. 16 edition of the Proceedings of the National Academy of Sciences.

Of the 129 species of marine mammals on Earth, including seals, dolphins and polar bears, approximately one-quarter are facing extinction, the study said.

“It’s important to protect marine mammals if you want to keep the ocean’s ecosystems functional,” said study co-author Paul Ehrlich, professor of biology and senior fellow at the Woods Institute for the Environment at Stanford. “Many of them are top predators and have impacts all the way through the ecosystem. And they’re also beautiful and interesting.”

Mapping marine mammals

To pinpoint areas of the ocean where conservation could protect the maximum number of species and the ones most vulnerable to extinction, the researchers overlaid maps of where each marine mammal species is found. Their composite map revealed locations with the highest “species richness” — the highest number of different species.

“This is the first time that the global distribution of marine mammal richness has been compiled and presented as a map,” said co-authors Sandra Pompa and Gerardo Ceballos of the National Autonomous University of Mexico. “The most surprising and interesting result was that all of the species can be represented in only 20 critical conservation locations that cover at least 10 percent of the species’ geographic range.”

The researchers identified the 20 conservation sites based on three main criteria: how many species were present, how severe the risk of extinction was for each species and whether any of the species were unique to the area. The scientists also considered habitats of special importance to marine mammals, such as breeding grounds and migration routes.

Nine key sites

It turned out that preserving just nine of the 20 conservation sites would protect habitat for 84 percent of all marine mammal species on Earth, the scientists found. That’s because those nine locations have very high species richness, providing habitat for 108 marine mammal species in all.

These nine sites, which make up only 4 percent of the world’s ocean, are located off the coasts of Baja California in Mexico, eastern Canada, Peru, Argentina, northwestern Africa, South Africa, Japan, Australia and New Zealand, the study reported.