Federal officials are trying to understand what is behind a sharp rise in the stranding and deaths of threatened fur seals, with dozens washing up along the California coast this year.

Designating it an Unusual Mortality Event, NOAA Fisheries said that as many as 80 Guadalupe fur seals have appeared on shore, about half of them dead and the other half starving. That is eight times more than normal. The "unusual mortality" designation allows for additional funding and international scientists to be directed to examine the problem.

"We are significantly higher than what we would normally expect here in California," said Justin Viezbicke, the NOAA Fisheries Stranding Coordinator for the West Coast region, of the strandings that averaged under 10 a year from 2009 to 2014 and about 12 animals per year over the past three decades.

Many of the fur seals, which breed almost entirely on Guadalupe Island off the coast of Baja California, Mexico, have been turning up emaciated but scientists can't say exactly why. Hunting brought the species to near extinction in the late 1800s, but it is slowly recovering. The species current population is estimated at more than 10,000 animals.

One theory for the strandings is that waters in the Pacific Ocean off of California have warmed over the past two years, pushing the fish they feed upon further north.

"The conditions in the Pacific Ocean have been anomalous for almost two years now," Toby Garfield, director environmental research division at the NOAA Southwest Fisheries Science Center, said, referring to a warm patch of water known as the blob that formed in the Gulf of Alaska and a high pressure ridge that has kept winter storms further north towards Washington and Canada.

"The result of that is we have seen some real species changes, especially with a lot of the forage fish that fur seals and sea lions would be feasting on if you will," Garfield said.

Garfield said he expected the warming conditions would persist for a few more months.

Complicating the picture is the arrival of one of the strongest El Ninos on record later this year, which is expected to bring frequent and intense storms to California, along with an increase in tropical cyclones in the Pacific and heavy rainfall and snowfall.

The surge in fur seals deaths follows several months in which more than 1,000 starving sea lions were turning up along the California coast.

While both species were found emaciated, NOAA officials said they couldn't say for sure where they are being impacted by the same conditions.

"They are in the ocean and sharing the same space so there is always that possibility that they are connected," Viezbicke said. "But because they are such different species and they do have different ranges and some different foraging that we noted, there is enough difference to separate them. But being in the same type of conditions, that potentially is playing into this for both of them absolutely."