Three sperm whales and 18 dolphins have washed ashore on beaches in central California, mystifying wildlife experts, who can't say what is causing the mass deaths.
"We don't know what's going on," said James Lecky, chief of the protected species division for National Marine Fisheries Service in Torrance, Calif. "We aren't sure if these animals have encountered something out there that has made them sick. It will take a little bit of work to find out."A network set up by government biologists is responding to the emergency, which began to be noticed April 21 along the coast of San Luis Obispo and northern Santa Barbara counties.
Some animal carcasses have been collected, but test results aren't expected for days or perhaps months. Wildlife experts suspect a range of causes.
The natural ocean currents could be sweeping the dying or dead animals to this stretch of coastline, making it look worse than it is, Lecky said.
"We have seen where ocean currents drop animals on the beach," he said. "But there may be other factors at play."
One such factor could be a viral epidemic similar to those responsible for the deaths of bottlenosed dolphins on the East Coast and in the Gulf of Mexico in the past few years, Lecky said.
So far, the morbillivirus, which is still little understood, has not yet been seen in Pacific Ocean populations, he said.
Another cause could be blooms of biotoxins, such as the dinoflagellate algae, which have killed marine mammals in the past.
Exposure to toxic chemicals or other human causes are also possible, Lecky said.
Gill nets have killed whales and dolphins in the past, he said. "But usually cetaceans show scars if they drown in nets. We're not seeing that, but it's not outside the realm of possibility."
The fishing expeditions for swordfish and thresher shark, which generally are blamed for gill net deaths, are not being conducted now, he added.
Nor are deep-water soundings or other tests by the U.S. Navy or other parties - "nothing that we're aware of," Lecky said.
Seismic testing to find oil deposits is taking place off Morro Bay, but it hasn't been blamed for mammal fatalities, he said.
If the cause is obvious, the investigation results will be known in a few days. But it could take months if the investigators have to wait for results from biological and toxic chemical tests, he said.
A full-grown female sperm whale washed up near Pismo Beach on Sunday.
A 14-foot baby was found Monday at Minuteman Beach, 35 miles south of Vandenberg Air Force Base. Another sperm whale calf was discovered in Cambria several days ago.
The dolphins began washing up, some alive, two weeks ago. Most thrashed to their death while stranded on the beach. But others swam back into the ocean.
"They usually don't get onto the beach until they're on their last legs," Lecky said. "Then they're pretty far gone."
Neither species is endangered.
About 900,000 dolphins, which grow to 40 feet, are estimated to live in the Pacific Basin, the region from California to Japan and Alaska to the equator. Sperm whales are thought to number about 930,000.