The North Olympic Peninsula’s sea otters show signs of having been exposed to pathogens that are killing other sea mammals, but they don’t seem to be affected since the population is growing, a federal researcher based in Port Angeles said.
“Although we’re seeing evidence that they’re exposed, we’re not seeing mortality,” said Mary Sue Brancato, co-author of a comprehensive study on the Peninsula’s sea otters.
“It’s a very good sign,” said Brancato, who is a resource-protection specialist at the National Oceanic and Atmospheric Administration’s Olympic Coast National Marine Sanctuary sanctuary in Port Angeles.
Researchers took blood and liver samples from sea otters off the Washington coast in 2001 and 2002 for the study published by the sanctuary and the U.S. Fish and Wildlife Service and its partners.
Eighty percent of the otters tested positive for morbillivirus, which can cause serious disease in some animals and humans.
It was the first time the virus was detected in sea otters, the study found.
About 60 percent of the otters tested positive for toxoplasmosis, a parasitic disease that has been responsible for the deaths of southern sea otters in California.
There were traces of chemical contaminants, but the levels didn’t raise concerns, said Jay Davis, co-author and resource contaminant specialist for the Fish and Wildlife Service.
“What surprised us was that disease threats were the biggest concern versus contaminants,” Brancato said.
The study, to which dozens of scientists contributed, was “an eye-opener,” because it showed the presence of significant pathogens in Washington sea otters, said Ed Bowlby, another co-author of the study, and a marine biologist and sanctuary research coordinator in Port Angeles.
“This is a baseline that’s been established now for the Washington sea otters,” he said.
The information is important because sea otters are a keystone species for the area, said Brancato, a Sequim resident.
“They are what keep the kelp and sea urchin populations in balance,” she said.
“We should care because of where they fit in the ecosystem.”
Population on rise
The 181-page study released Tuesday shows the Washington sea otter populations is on a steady rise despite the presence of contaminants and harmful pathogens that have caused disease in other marine mammals.
“Ours are lucky to live in a pristine coastline,” Brancato said.
Scientists say there are about 1,100 sea otters in Washington, 99 percent of which are off the Pacific coast.
“The population is expanding, but it’s still at risk because it’s a small population in general,” Brancato said.
The numbers are remarkable considering the history of the species.
A commercial harvest for sea otter pelts extirpated — totally wiped out — the species here around 1913, Bowlby said.
“The last one was shot north of Grays Harbor.”
The species was re-introduced to Washington in 1969 and 1970, with individuals brought in from Alaska.
Making comeback
Slowly but surely, the sea otter is making a comeback.
“The public is very much drawn to them,” said Bowlby, also of Sequim. “They’re fascinating animals to watch.”
Sea otters rise to the surface to eat, something they don’t take lightly. Sea otters consume about 25 percent of their body weight every day, Bowlby said.
Since they are relatively sedentary, sea otters are highly susceptible to localized contamination.
“They tell you about the environment they live in, because they don’t move around,” Brancato said.
Sea otters prey on sea urchins, which in turn feed on kelp. Based on limited research, scientists believe sea urchins thrived and kelp declined when the sea otters were gone, Bowlby said.
Kelp is important because it provides habitat for many kinds of species, Bowlby added.
The northern sea otter is federally protected under the Marine Mammal Protection Act. Washington sea otters were listed as endangered in 1981.
Scientists at the sanctuary will continue to survey sea otters as part of an inter-agency census. Further studies will occur should the population begin to nose dive, Bowlby said.
“It’s very good news our [sea otter] population is still growing,” Brancato said.
“I’m cautiously optimistic, but I don’t want us to forget they’re still at risk.”
The full name of the report is: “Chemical Contaminants, Pathogen Exposure and General Health Status of Live and Beach-Cast Washington Sea Otters.”
It can be viewed online at www.sanctuaries.noaa.gov/science/conservation/brancato.html.
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Reporter Rob Ollikainen can be reached at 360-417-3537 or at rob.ollikainen@peninsuladailynews.com.
