Researchers are trying to determine whether there's a link between runoff waters and the deaths of sea otters along the Central Coast.
The state Water Resources Control Board recently approved nearly $500,000 to find out whether polluted runoff is killing sea otters from Half Moon Bay to Santa Barbara.
There are now about 2,300 otters. Their numbers have thinned because of a high death rate from disease.
"It's just a really interesting puzzle -- what is going on with otters -- because they are a sentinel species," said Karen Worcester, who is administering the grant through the Central Coast Regional Water Quality Control Board in San Luis Obispo. "They are at the top of the food chain, and they are voracious eaters."