Number of Sea Otters Rises in California

The number of sea otters living in California is increasing, according to a latest study by UC Santa Cruz scientists and federal researchers.

The latest survey estimated the number of otters in the state to be 2,941. Every year, The U.S. Geological Survey scientists calculate the average population index for the southern sea otter (Enhydra lutris nereis).

Researchers said that the rise in population in the past few years can be attributed to the rise in the number of pups and the addition of San Nicolas Island sea otters to the population count. The survey team included researchers from the USGS, UC Santa Cruz, California Department of Fish and Wildlife's Office of Spill Prevention and Response, Monterey Bay Aquarium, and other institutions.

"Population growth in central California has faltered recently, so the fact that we're seeing a slightly positive trend is a basis for cautious optimism," said Tim Tinker, a biologist with UC Santa Cruz and the USGS Western Ecological Research Center. "Certainly, sea otters have made an impressive recovery in California since their rediscovery here in the 1930s."

The population index is calculated as multiple-year average using data from annual surveys to compensate for any variability. The index gives the scientists a more accurate picture of otter population.

"We counted a record number of pups this year, which led to the uptick in the 3-year average," said USGS biologist Brian Hatfield, coordinator of the annual survey, according to a news release. "A high pup count is always encouraging, although the number of adult otters counted along the mainland was almost identical to last year's count, so we'll have to wait and see if the positive trend continues."

The 2013 survey of sea otters in California also included sea-otters living in San Nicolas Island. These otters were initially brought to the island as a USFWS recovery experiment.

Sea otters are an aquatic member of the weasel family and are found near the coasts of Pacific Ocean in Asia and North America. By the early 20^th century only 2,000 sea otters were in the wild. Now, their population is increasing. About 100,000 to 150,000 sea otters are protected by law, according to the National Geographic.