SANTA CRUZ -- An annual survey of California's sea otter population shows another slight increase in the playful critter's numbers, a step in the right direction and a reason for glimmers of optimism among scientists.
The count of 2,882 otters just off the California mainland is an increase of 90 compared to the prior year, up more than 3 percent. However, scientists also are now including a population of previously uncounted otters at San Nicolas Island, bringing the total to 2,941.
"The takeaway message is not so different from last year. It's cautiously optimistic," said Tim Tinker, a research biologist with the U.S. Geological Survey's Western Ecological Research Center and an adjunct professor at UCSC. "Not exactly runaway growth, but there are slight increases in areas."
The survey is conducted annually and uses a three-year average to smooth out variations in counting methods. Once near extinction, the otters' population must exceed 3,090 for three consecutive years to be considered for removal from a federal threatened species list.
The number of sea otter pups counted this year was extraordinarily high, though Tinker cautioned that may be no more that a coincidence due to the timing of when scientists did the study.
The number of sea otter strandings continues to be high too, driven mainly by something that remains a bit of a scientific mystery -- great white sharks off the Southern California coastline are killing sea otters at a high rate.
Sharks don't eat otters, but large numbers are showing up dead from shark "tasting" bites. The phenomenon is under scientific scrutiny, including whether large numbers of inexperienced juvenile sharks are to blame.
"I think the jury's out still on the numbers of white sharks. All we know is the bites are increasing exponentially," Tinker said.
Those deaths are leading to declines in otter numbers in that part of the state, while the otter population in the central portion of California, north to Monterey, appears to be stagnant due to food supply limits.
Within the Monterey Bay, Tinker said cyanotoxins and domoic acid, both occurring from natural algae blooms, seem to be factors in otter mortality here. He also said the USGS, in conjunction with the Monterey Bay Aquarium, is set to embark on a new study of otters in Elkhorn Slough, tagging 20 of them and following them for several years.
Playing a critical role in near-shore ocean ecology, as many as 18,000 sea otters once frolicked off California before being hunted to near-extinction for their thick pelts. A surviving population was discovered near Big Sur's Bixby Bridge in the 1930s, and otters' numbers have climbed slowly upward since.
Thursday's count was met with optimism by those helping to nurture sea otters back to vitality.
"This is really fantastic news," said Steve Shimek, chief executive of Monterey-based The Otter Project. "The California sea otter is considered an iconic endangered species and to see it scrap back from the brink within our lifetimes is a true success story."
Jim Curland, advocacy program director for Moss Landing-based Friends of the Sea Otter, said the numbers were positive but that otters weren't out of the kelp forest yet.
"This increase can't be seen as a sign that the sea otter is out of danger yet," Curland said. "We're still struggling to understand how disease, shark attacks, food limitations and other threats have kept this popular animal on the brink over the last three and a half decades."
Researchers from the USGS, the California Department of Fish and Wildlife, Monterey Bay Aquarium, UCSC and other institutions collaborate annually to conduct the survey.
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After a brief dip, annual sea otter counts are on the rise again.
*Includes 59 previously uncounted San Nicolas Island otters
SOURCE: U.S. Geological Survey