Otters struggle to keep numbers afloat

A sea otter scopes us out along the Montana de Oro coast.
Photo by Joe Johnston 8-2-07
A sea otter scopes us out along the Montana de Oro coast. Photo by Joe Johnston 8-2-07 The Tribune

Researchers say California’s sea otter population continues to struggle.

Survey results from the last three years show a slight downward trend in the otter’s population. The average number of otters counted from 2007 to 2009 showed a half a percent decline, according to scientists with the U.S. Geological Survey.

Last year, observers counted 2,654 otters. The otter’s numbers must stabilize at 3,090 over three years in order for federal wildlife officials to consider removing it from the Endangered Species list.

Indicators scientists watch to assess the status of the sea otter population are a combination of good and bad. Otter mortality due to disease and other factors among breeding-age adults remains high, but the ratio of pups to adults showed a slight increase last year.

“This year’s census results demonstrate that sea otters continue to experience levels of mortality sufficient to limit recovery,” wrote lead USGS scientist Tim Tinker in a post-census report.

The assessment of the survey results by The Otter Project, a Monterey-based conservation group, is grimmer. They think the data show a population decline.

“It is too soon to tell how steep the decline will be, however any change in direction of demographic trends should be taken seriously by management agencies,” the group said in its most recent assessment.

High levels of infectious disease remain a key concern, the group said. The animals suffer from a variety of diseases caused by bacteria, viruses and parasites.

The heart of the sea otter’s range is Monterey and San Luis Obispo counties. Last year, male otters — which tend to be more migratory — congregated in Estero Bay, between Cayucos and Montaña de Oro, rather than migrating past Point Conception in Santa Barbara County.

Reach David Sneed at 781-7930.