NEWPORT BEACH, Calif. — In a possible sign of ocean warming, a rare sea snake has turned up on a Southern California beach.

Researchers announced Thursday that the venomous yellow-bellied sea snake was found by a beachgoer on Tuesday at Newport Beach. It was weak and sick and was euthanized on Wednesday.

The 25-inch long female is only the fifth ever found in California. One was found in 1972.

Three others have turned up in the past three years.

Researchers say their appearance may be a sign that the oceans are warming. The species usually lives farther south in tropical waters off Mexico and Central America.