A promising recent resurgence of juvenile sea stars along the California coast has yet to find its way to the Pacific Northwest, according to experts.

The sea-star population from Alaska to northern Mexico was decimated in the past year. And a mysterious disease called Sea Star Wasting Syndrome is to blame.

As the name suggests, populations of sea stars waste away within weeks. Those infected twist, contort, lose arms and lose the ability to hold onto rocks before finally dissolving.

Recently, the population of juvenile six-armed sea stars has shown “a little bit” of growth.

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But the resurgence isn’t necessarily moving north.

“We’re seeing a little bit in this one species, but we’re not seeing it up and down the coast,” said Brian Tissot, director of the Humboldt State University Marine Laboratory and the Marine and Coastal Science Institute in Northern California.

Experts say six-armed sea stars aren’t as ecologically important as the ochre sea stars.

Drew Harvell is a Cornell University marine epidemiologist based at Friday Harbor Labs and part of a nationwide group of researchers studying the wasting disease. In Washington, she said, the ochre or purple sea stars, or Pisaster ochraceus, haven’t been so lucky.

“I know we had a large recruit in the San Juan (Islands) and a lot of them did not make it,” she said, citing the wasting disease.

When juveniles become infected with the wasting disease, “they don’t show the same signs as the adults because they die so quickly. Once they become infected, they just disappear,” she said.

Researchers in Oregon have also only seen small numbers of resurgence.

“We have some of that in two, three of our sites. It hasn’t been a widespread thing that we’ve seen in the Humboldt (Calif.) region,” said Bruce Menge, a professor of marine biology at Oregon State University in Corvallis.

Scientists are documenting the disease and its impact on the number of sea stars in the intertidal ecosystem. Instances of the disease “still remains very high, even though the number of animals is fewer,” Menge said.

The lack of sea stars already is starting to change the outlook of the ecosystem.

“We’re already seeing a large increase in barnacles,” Menge said.

Normally, sea stars reduce the population to “very low numbers” at this time of year but this isn’t happening, he said. “As a result, the prey that do settle on the rocks, survive and grow like crazy.”

Caitlin Cruz: 206-464-2466 or ccruz@seattletimes.com