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According to data released Friday by the U.S. Geological Survey and partners, the three-year average of the total counts of southern sea otters was down from last year’s high, although it still exceeded the U.S. Fish and Wildlife Service’s delisting threshold for a second straight year.
Researchers surveyed sea otter populations along the mainland coast, from Pigeon Point in the north to Gaviota State Park in the south, and also the distinct population at San Nicolas Island in the southern California Bight. This year’s overall count of 3,186 exceeded the 3,090 threshold set by the FWS. The otters’ numbers must surpass the threshold of 3,090 for another year before the FWS would consider delisting the subspecies, which is currently designated as “threatened” under the Endangered Species Act. The count is down by 3 percent from 3,272 in 2016’s survey. This dip reflects a decrease in the numbers of sea otters counted along the California mainland.
n contrast, sea otter abundance at San Nicolas Island continues to show an increasing trend, growing over the past decade at a mean rate of 10 percent per year. This population was established by translocation in the late 1980s and struggled at low numbers through the 1990s.
“The lower mainland count this year could be due to poorer counting conditions and very sparse kelp canopies, which likely influenced sea otter distribution,” says Dr. Tim Tinker, a research ecologist who leads the USGS California sea otter research program. “However, we cannot rule out the possibility that increased mortality also played a role.”
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Photo via USGS.
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