A sea snail considered a treasure of the U.S. West Coast, prized for its beautiful shell and considered a dining delicacy, is not at risk of extinction and does not require protection, federal officials say.

The National Marine Fisheries Service, after considering petitions by conservation groups, has said the pinto abalone does not warrant protection under the federal Endangered Species Act at this time.

Found from Alaska south to Baja California, the pinto abalone's distinctive green and red mother of pearl shell is coveted for decorative uses, while the large fleshy foot is considered a culinary treat.

The fisheries service said it based its decision not to list it as endangered was based on expert evaluation of the abalone's status.

"Over-harvest and inadequate enforcement has impacted the abundance and population growth of wild populations, but not to the point that the species is likely at risk of extinction now or in the foreseeable future," the service said in a statement.

In 2013 two conservation groups, the Natural Resources Defense Council and the Center for Biological Diversity, petitioned the service, asking for a review of the status of the pinto abalone.

They argued that the species requires federal protection under the Endangered Species Act because populations of the species have plummeted across large parts of their range.

"The pinto abalone has virtually disappeared from its historical range in Northern California and is declining in its Southern California range," the Center for Biological Diversity said in its petition.

Conservationists blame the disappearances of the pinto abalone, which at one time supported commercial fisheries all along the western coastline, on overfishing and ocean acidification brought on by climate change.

"These are species that science shows ocean acidification and climate change are going to do it in," says Brad Sewell, a senior attorney for the Natural Resources Defense Council. "The only way of saving the species is to address the health of the species early on and get it back to robust diverse populations."

In refusing protection under the Endangered Species Act, the fisheries service, a division of the National Oceanographic and Atmospheric Administration, did say the mollusk would remain on its "species of concern" list.

However, it said, the pinto abalone "is not presently in danger of extinction, nor is it likely to become so in the foreseeable future, throughout all or a significant portion of its range."

Sewell expressed disappointment over the decision.

"While I'm still reviewing the decision, it is discouraging," he says. "I don't know if the agency is going to wait until the species nears extinction, and if that's the case it's a poor strategy."