Staff at the Vancouver Aquarium are scratching their heads over what is causing thousands of sunflower starfish to die in the waters of Vancouver Harbour and Howe Sound.

Aquarium’s dive team started noticing the overpopulated starfish wasting or completely disintegrating ever since early September.

“Now they are gone. They have disintegrated, and now there is just goo left,” says research diver and taxonomist Donna Gibbs. “So we are trying to see as much as we can really fast and get reports from divers in other areas to see how widespread this is.”

While researchers do not have any clear answers yet, they believe some sort of disease might be at the root of it.

“We think it is disease. It is overpopulation and pestilence,” says Gibbs. “The numbers grew so out of control and then a disease hit them and just wiped them out. That is what we think. We are not sure yet, but that is the first thought.”

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But, Gibbs says they are seeing baby starfish that looks healthy, so there’s hope the population may rebound.

Video: Hutt Island before and after die-off. Courtesy of Vancouver aquarium.

Gibbs says the die-off will have an effect on the ecosystem.

“It smothered everything out and now there is all this space for things to settle and grow on.”

Still, the sight of so many dead starfish is a startling find for any diver, says Gibbs.

“It is shocking to see them all dead. They are just gone. And, are they coming back? We want them back. B.C. is known for its sea stars. We have more species here than anywhere else in the world.”

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Vancouver aquarium has sent off some samples for analysis, but it will take time to know for sure what is causing the starfish to die.

“As data starts to trickle in, we will try to figure out if there is an answer… If we ever figure it out,” says Gibbs.

Meanwhile, Vancouver aquarium is asking local divers to keep an eye on starfish populations in local waters and report anything unusual to fishlab@vanaqua.org .