Water temps are a factor

Marine mammal rescuers believe warmer ocean is making food harder for sea lions to catch. Starvation is commonly seen.

July 10, 2009|By Liyna Anwar

Marine mammal experts may have realized why a large number of seals and sea lions are coming ashore weak and malnourished. The mammals are having a hard time catching fish due to a slight increase in the temperature of the ocean, said Dr. Richard Evans, the Pacific Marine Mammal Center veterinarian and medical director.

Experts are predicting an El Niño/La Niña weather pattern will begin to arrive through August, with higher global ocean temperatures already evident, according to data from the National Centers for Environmental Prediction.

“California sea lions, which don’t dive as deep as elephant seals and harbor seals, are having more trouble finding food. With warmer waters, the fish are swimming deeper and that’s where the problems seem to be coming in,” said Melissa Sciacca, a spokeswoman for the center.


Although it is only halfway through the year, the center has treated 213 animals — already 20 more than the total number they treated all of last year.

The influx in animals to the center has caused a 63% increase in the cost of food and medication for the seals and sea lions compared to 2008. The amount of time, manpower and space that is needed to care for the animals is also stretched thin due to the increase.

“Many of us are working until midnight, seven days a week,” Evans said. With so many animals under the center’s care, transferring them from day environment to night environment becomes quite a task.

“It creates a logistical nightmare. It’s a tremendous amount of work,” he said.

There is no definite reason yet as to why there has been such an increase in the mammal strandings; however, according to Evans, one of the reasons may be due to a small but substantial increase in the ocean temperature recorded this year. This causes problems with fish availability for the marine mammals. Seals and sea lions would have to dive deeper to reach colder waters in order to obtain their food, he said.

“Plankton, which fish eat, will go other places because they like cold water. As plankton move, fish move with it. It’s all part of an ecosystem,” he said.

Unfortunately, diving deeper to get food is not always an option for all marine mammals, Sciacca said.

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