Warmer Ocean Waters Possible Cause of Sea Lion Crisis on West Coast

californiasealion_pup_sm-nmmlSince 2015, over 1,200 California sea lions have been calling rehabilitation centers home across the state. In Sausalito’s Marine Mammal Center, more than 400 sea lions have been admitted, with others in the hospital recuperating.

Experts are of the belief that the dramatic increase in the number of sea lions, pups specifically, washing ashore may be attributed to large areas of warming waters in the Pacific affecting food sources for sea lions. Warming waters have been recorded from Alaska to the Aleutian Islands, along the coasts of Oregon, Washington and California and then out to Hawaii.

It’s easy to attribute the warming waters to El Niño but a lot of the areas are actually the result of strong southern and weak northern winds brought about by changing currents with not enough upwelling to distribute colder water. In fact, some areas in Pacific waters are warmer by up to five degrees Fahrenheit compared to their usual temperature for the time of the year. According to Nate Mantua, a climatologist from the National Oceanic and Atmospheric Administration, some of the temperatures recorded for 2015 are the warmest ever reported.

An El Niño event for the year has been announced but scientists are looking at climate change, assessing the kind of role it is playing in the plight of California sea lions through widespread warming of waters and sea ice melting. Human activities that massively impact the ocean environment, like pollution and overfishing, don’t help improve the situation either. Recent assessments have revealed that the sardine population, for example, has dropped 72 percent since 2006, its peak. Sardine is a major component of the sea lion diet.

With fish scarcer in the usual areas they feed in, sea lion mothers have to spend more time looking for food, sometimes leaving their pups for up to a week before being fed. When mothers are gone too long, the pups lose energy, resulting in a slower growth process. Pups that tire of waiting for their mothers head out to sea and they’re the ones ending up washed ashore. Unfortunately, pups are generally weaned in April. If they go out to sea before that, they don’t have high chances of survival.

“What’s scary is that we don’t know when this will end. This could be the new normal-a changed environment that we’re dealing with now,” said Dr. Shawn Johnson, veterinary science director for The Marine Mammal Center in Sausalito.

–From Tech Times

Categories: California Sea Lion Deaths, Condition of Oceans

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