Deaths of Sea Lions Do Not Concern Experts

More than a thousand of San Miguel Island’s sea lions--including their newborn pups--have died since early summer, as El Nino’s warming effects have driven away their meals.

But the deaths are not worrying experts at the Channel Islands National Marine Sanctuary.

“El Nino has long been known for its natural population control,” said sanctuary manager Ed Cassano.

Citing 1983’s El Nino effects, when many sea lions faced similar fates, Cassano said this is just a cycle of life: Some mammals die, others repopulate.

Sea lion pups are born at San Miguel from June to November, Cassano said. During that time, about 1,500 sea lions have died.

But right before the series of deaths, there were at least 100,000 sea lions--a larger-than-usual number--at San Miguel, which is known for its usually nutrient-rich environment, he said.

This fall’s unusual warming effects, however, have caused the island’s ecosystem to change. The high temperatures have driven away sea lions’ usual prey--squid and anchovies--to cooler spots, either deeper in the ocean or farther north, Cassano said.

Newborn pups are weaning from mothers who haven’t eaten their usual amounts. The result, inevitably, is death for many more seals, he said.

Though animal lovers might not be able to stand the decay of corpses floating in the ocean, crabs, sharks and other hungry scavengers don’t have feelings of despair, he said.

Cassano added that the role of the sanctuary is not to alter the ecosystem by scooping up dying pups and saving them, unless there are unusual conditions in which a weakened sea lion might need special assistance. The sanctuary’s goal is to conduct research and monitor nature, he said.