A court-ordered settlement filed Wednesday requires the federal government to protect habitat for the endangered black abalone off California's coast.
Catherine Kilduff, a staff attorney with the Center for Biological Diversity, said the shellfish were once common in Southern California tide pools, but now have declined by 99 percent since the 1970s.
She said that, while fishing for black abalone is banned in California, overfishing initially depleted the population and poaching continues to hurt recovery.
Kilduff said a disease called "withering syndrome" is spreading and getting worse because of warming ocean temperatures and ocean acidification.
The syndrome causes abalone to lose their ability to cling to rocks.
She said the disease has caused black abalone virtually to disappear from the Southern California mainland and many areas of the Channel Islands.
Kilduff said the agreement requires the National Marine Fisheries Service to propose critical habitat for black abalone by September.
"They're essentially saying that they're going to manage this ecosystem in order that it's healthy for the black abalone," said Kilduff. "And by addressing ocean warming and ocean acidification, it will help not only the black abalone but the other species that are living in that ecosystem."
"Black abalone is on the cusp of extinction and could be California's first marine species lost to global warming," Kilduff continued. "Habitat protections can provide a basis for recovery of the black abalone, which is a crucial constituent of California's kelp bed ecosystems."
Black abalone were listed as an endangered species under the Endangered Species Act in January 2009, in response to a Center for Biological Diversity petition.
With that listing, federal agencies by law must protect the abalone's critical habitat.
"The loss of black abalone along the California coast is a warning: Our oceans are in trouble," said Kilduff. "Habitat protections are needed to improve the black abalone's chances for surviving the threats of global warming and ocean acidification."
She also said ocean acidification poses an increasing threat to the abalone's growth and reproduction.