Sea lion pups are becoming stranded on beaches, and in danger of dying, in Southern California, in Santa Barbara, Ventura, Los Angeles, Orange and San Diego Counties, and no one is certain why.
Sharon Melin, a wildlife biologist with the National Marine Fisheries Service, said it's not uncommon for sea lion pups to become stranded, but the recent occurrences have been troubling because of the scale, the time of year and the mystery surrounding their cause. As more pups leave their mothers, Melin added, the problem isn't likely to subside until summer. "Usually, we know the problem," she said. "We knew what was coming. When we saw the effect, we knew what it was caused by." Typically, that would be disease or warmer ocean temperatures, such as during an El Niño. "What's different about this incident," she said, "is we don't have any of that."The rate of pup strandings (a condition just prior to death) in the first three months of 2013 is already an order of magnitude higher than last year, with 214 strandings in San Diego County vs. 32 last year, 189 in Orange County vs. 20 last year, and 395 in Los Angeles County vs. 36 last year.
While the cause is uncertain, what is clear is that the pups are underweight and appear to be starving.
Researchers are certain, however, that the pups are moving away from the water to find warmth. All of the animals are starving, and therefore lack the body fat necessary to keep them warm in the water.But according to Reuters:
"[t]he oddest part of this is the pups should have been with their mothers," Melin said. "We think the mothers are having to go out farther and stay out longer to find food and the pups begin to forage on their own after they've been alone for some time."Mysteries such as this are pretty disquieting. There has been some speculation that Fukushima radiation is causing the pups' distress, but so far that is just that--speculation. Still, it's an angle that bears further investigation. More when I hear more.
But scientists remain unsure why the mother sea lions might be venturing out farther into the ocean.
. . .
"The vast majority [of pups] are coming in malnourished and dehydrated, since they get their hydration from the fish they eat," [Sea World spokesman Dave] Koontz said. "They stay with us [Sea World] three to four weeks or longer, until we get their weight up and then we return them to their habitat as soon as they are healthy enough."
. . .
"There really isn't an oceanographic explanation for what we're seeing," Melin said. "We're looking at disease as a possibility and also at the food supply, and it could be some combination."
Melin said there were no signs of such distress in other marine mammals that rely on the same sardines, anchovies, squid and other fish. Nor are the adult sea lions dying at an unusual rate.