The magnificent sunflower sea stars, pushed to the edge of extinction by sea star wasting disease, have been declared a “critically endangered species” by the International Union for Conservation of Nature.

The listing, announced yesterday, is supported by new studies that show a 90-percent decline in the overall population of sunflower stars. The species (Pycnopodia helianthoides) has been essentially wiped out in Oregon and California, with numbers greatly diminished from Puget Sound to Alaska.

Ecologists say sea stars are a key component of the complex marine food web. Among other things, they help maintain productive kelp forests by preying upon sea urchins that consume massive amounts of vegetation.

Experts hope that the critically endangered designation by the IUCN will bring greater public attention — and funding — to enhance studies, protection and restoration of sunflower sea stars. In Puget Sound, for example, researchers have begun work on a captive-breeding program that could eventually lead to restoration — including reintroducing the sea stars to important coastal habitats.

In the meantime, other researchers remain interested in finding a cause for sea star wasting disease, also called sea star wasting syndrome, which affects every species of starfish. Factors such as viruses and temperature conditions have been suspected as playing a role in the syndrome, but the infection remains poorly understood.

The latest and most widespread outbreak of the disease, which began in 2013 on the West Coast, has had a devastating effect on nearly all sea star species. While some species are beginning to recover in some areas — and some are doing quite well — it does not appear that the disease has ever gone away, according to Melissa Miner, a researcher with the University of California, Santa Cruz, who has helped coordinate a network of volunteer and professional observers from Mexico to Alaska.

To estimate the decline in sunflower sea stars, ecologists from Oregon State University worked with more than 60 other institutions to pull together field observations from Alaska to Baja California. They found no signs of a population recovery.

Information gathered during the project provided the basis for the critically endangered listing by the IUCN, noted OSU researcher Sara Hamilton, adding that she expects the full study to be reported next year in a peer-reviewed scientific journal.

The Nature Conservancy, a global conservation organization, funded the OSU project as well as the UW’s captive-breeding program at the Friday Harbor Labs in the San Juan Islands.

Walter Heady, senior scientist at The Nature Conservancy, said the likelihood that sunflower sea stars will recover on their own are slim. Further research will determine if a reintroduction program is appropriate for the species.

“This IUCN listing was the first step in our roadmap to recovery,” Heady stated in a news release. “While many of us were concerned about local extinction of the sunflower sea star, results of this study highlight the truly devastating extent of loss of this important marine species. This work provides the foundation for conservation of the species.”

Taylor Frierson of the Washington Department of Fish and Wildlife said the IUCN listing process has helped to identify key knowledge gaps and research goals for the sunflower star.

“The speed and scale of this widespread sea star die-off was absolutely perplexing,” Frierson said in the news release. “We saw these rapid changes ourselves while working underwater and immediately felt powerless to help. Then the cascading events seen throughout the range of the missing sunflower sea star had revealed their fundamental role in the nearshore ecosystem.”

The loss of sunflower sea stars has been associated with an explosive growth of purple sea urchins and a significant decline in kelp forests in several areas, including Northern California. Kelp, which is already under stress from warming ocean waters, provide critical habitat for thousands of marine animals, including fish and crabs that support coastal economies.

After the massive die-off of sunflower stars, Puget Sound has become essentially the southern portion of the range for the species, experts say. Scattered populations can be found in Hood Canal, the San Juan Islands and the Strait of Juan de Fuca. To the north, other populations can be found in British Columbia and Alaska.

The alarming decline of the sunflower sea star led some people to consider a threatened or endangered listing under the federal Endangered Species Act (see OpEd by Harvell-Gaydos) — and that is still an option — but the IUCN designation allows for more flexibility.

“The ESA works best when direct human actions are causing a species to go extinct,” noted Sara Hamilton, adding that it isn’t clear what actions are needed to counteract such a “mysterious disease” as sea star wasting syndrome. Since sunflower sea stars are occasionally caught in crab traps, the Dungeness crab industry could be affected by an ESA listing.

Because the IUCN listing is supported by scientific information, the findings can be used to raise public awareness without legal ramifications. The IUCN “Red List of Threatened Species” is a comprehensive source of information on animals, plants and fungi. It includes data on each population’s range, size, habitat, threats and conservation actions.

The captive-breeding program at Friday Harbor Labs, the first of its kind, started last year with the collection of 30 sunflower stars from local waters. After learning to feed and care for the animals, the challenge was to get the sea stars to spawn and then to help the free-swimming offspring survive and eventually settle down, according to senior research scientist Jason Hodin, who heads the project.

“To me, this is the most radical transformation of any metamorphosis in the living world,” Jason said. “The larvae feed on microalgae, and they look nothing like adults. Then, at the end of their larval period, they have to find their way to appropriate habitat and transform their bodies into a form that can live on the seafloor.”

Learning through trial-and-error and after resolving many challenges — including cannibalism among the young sea stars — the researchers were able to declare success in breeding to the juvenile life stage. Although many juveniles were lost during the program’s first year, 14 have survived and are still growing. The program will continue with another round of spawning beginning next month, as researchers watch continued growth among the inch-long juvenile starfish.