In a recent report there was no evidence of infection or toxin contributing to the death of the sea pups. There was no apparent study of the possibility of radiation. There was simply not enough food.
It’s not easy for scientists to figure out what’s killing animals that spend most of their lives offshore and out of sight. Of the 60 unusual mortality events declared by NMFS since 1991, researchers have found the cause of fewer than half. Marine biotoxins, poisons produced by microscopic algae, accounted for roughly 50 percent of those, and infectious diseases a quarter. The last three events for sea lions were the result of poisoning by domoic acid, a biotoxin that can build up in shellfish, sardines, and anchovies, and affect the neurological functioning of the mammals that eat them, including sea lions and people. Symptoms include seizures and disorientation, including sea lions wandering inland and walking the streets.
But this year, researchers didn’t see symptoms typical of poisoning or infectious disease, says Sarah Wilkin, an NMFS marine biologist and its stranding coordinator for the Southwestern United States. The sea lion pups weren’t having seizures. And on the whole, they weren’t showing signs of disease, such as breathing problems, runny noses, and diarrhea. NMFS researchers took blood and tissue samples from living and dead pups to test for bacteria, viruses, biotoxins, and other contaminants; they checked their stomach contents—measures that Palmer and her team, in crisis mode, didn’t have the resources to handle.
Now, roughly four months later, NMFS researchers are still compiling the test results. But so far, it seems, the pups weren’t sick; they were just hungry. Many arrived weighing less than half of their normal body weight and were dehydrated. For some reason, they had stopped nursing early and weren’t getting as much food as they needed; in many cases, simply providing the pups with fish seemed to restore them to health.
There has been little information about the demise of the sea pups. This piece is interesting for what they did not find. Perhaps it was some unexplainable anomaly. This story will be followed into next season to see if there is a repeat.
Another posting looked at fish that have been destroyed by the intake of power plants on the West Coast, and indicates that:
Fish of all species have been dramatically declining in population all along the California coast, which is likely contributing to the starved sea lions that have been washing up on Orange County beaches in large numbers this year, according to a study by the University of California, San Diego. Based on data collected from the filtration systems of five coastal California power plants since 1972, the study shows a 78 percent drop in not only commercially fished species, but also the smaller “forage” fish like sardines that provide sustenance for larger predatory fish and sea birds.
The data is not detailed enough to know how much of the decline is since the nuclear reactor disaster at Fukushima. It does show a disturbing loss of fish population over the past 40 years,
- WILDLIFE : Galapagos sea lions threatened by human exposure (environmentaleducationuk.wordpress.com)