Southern sea otter numbers have declined off the coast of California since their most recent high in 2016. According to data just released by the California Department of Fish and Wildlife (CDFW) and U.S. Geological Survey (USGS), the three-year average population index this year dropped to 2,962, which is 166 sea otters fewer than the 2018 survey.
This year’s surveys found that the
population of sea otters was largest in the central part of the species’ range,
which is between Seaside and Cayucos, and that the five-year trend for this
portion of the range remains positive. The specific areas where the population
trends are most negative, from Pigeon Point to north Monterey Bay and most
areas south of Cayucos, coincide with the areas known for high shark bite
mortality.
“One factor likely contributing to
the positive trend in the central range is the recent increase in sea otter
prey availability: sea urchins and mussels,” said Mike Harris, senior
environmental scientist with CDFW.
In addition to the sea otter
population along the mainland California coast, USGS and partners also survey sea
otters at San Nicolas Island in the Southern California Bight.
This population, established by
introducing sea otters back into the area in the late 1980s, struggled at low
numbers through the 1990s. However, over the last decade, the population has
grown rapidly at an average rate of about 10 percent per year.
Scientists have been counting sea
otters since the 1980s.
Southern sea otters are a protected
species under the federal Endangered Species Act and Marine Mammal Protection
Act and listed as a fully protected species under California law. Sea otters
play a critical role in the nearshore marine ecosystem, serve as indicators of
ocean health, and keep important elements of coastal ecosystems, like kelp
forests and seagrass beds, in balance.
Last year’s numbers were significant
in that they marked the third consecutive year the three-year average of the
population index had exceeded 3,090 – which is a condition of the U.S. Fish and
Wildlife Service’s (USFWS) Southern Sea Otter Recovery Plan to consider the
species for delisting under the Endangered Species Act.
Sea otters were presumed extinct in
California after the fur trade years. Although a small group of sea otters near
Point Sur was known to locals and state employees when the state of California
granted them “fully protected” status in 1913, they were rediscovered by the
public in the late 1930s, when up to 150 animals were documented near Bixby
Creek north of Big Sur.
Find a stranded sea otter? Contact
one of the institutions listed on this webpage.
