The creatures are dying of sea star wasting syndrome, an affliction that causes white lesions to develop on the starfish's skin and an unnatural twisting of the arms, the Anchorage Daily News reported. The starfish die after losing their arms and their tissues soften.
Marine scientists say the disease is killing massive numbers of starfish colonies up and down the West Coast, and it has been observed as far south as San Diego.
Scientists don't know how many of the tens of millions of starfish along the coast have the disease.
Pete Raimondi, a professor of ecology and evolutionary biology at the University of California in Santa Cruz, told the newspaper it may be in the tens of thousands to the low millions. The symptoms appear to be highly present among starfish in captivity, he added.
In Alaska, researchers first discovered evidence of the wasting disease last summer on Kayak Island in the Gulf of Alaska. They found a number of diseased sea stars, replacing an earlier theory that the illness was linked to warmer water, he added.
"It was the last place on earth where we would have expected to see it," Raimondi told the Daily News.
His group, the Pacific Rocky Intertidal Monitoring Group, was working with the Sitka Sound Science Center to conduct coastal biodiversity surveys.
At the Anchorage Museum, curator Greg Danner said the disease seems to have vanished since November. Before that, the museum euthanized a total of eight sea stars between August and November. Symptoms ranged from white lesions to a sea star that lost two arms during the day.
The museum changed its aquarium practices, including controlling tank temperature by limiting the number of hands in the water, and that may have made a difference, he said.
Raimondi said it appears that species are affected differently depending on their physical location. For sea star species in tide pool areas, death may follow in weeks or not at all after lesions or sores show up.
But the results are catastrophic and quick for underwater species with less physical structure in the environment, Raimondi said. Decay can take place within hours or a day.
At the Sitka Sound Science Center, aquarium manager Taylor White said that she and others haven't seen the same impacts that have been described in the Lower 48 states.
"It's honestly not that extreme up here," she said.
Researchers in Sitka are hoping to get more data to track the disease, White added.
Raimondi's team plans to return to Sitka Sound in March to sample established survey plots to better understand the wasting syndrome.
Information from: Anchorage (Alaska) Daily News, http://www.adn.com