ANCHORAGE, Alaska — The toxic algae blooms in the Pacific Ocean stretching from southern California to Alaska — already the largest ever recorded — appear to have reached as far as the Aleutian Islands, scientists say.

“The anecdotal evidence suggests we’re having a major event,” said Bruce Wright, a scientist with the Aleutian Pribilof Island Association, the federally recognized tribal organization of Alaska’s native Aleuts. “All the populations [of marine mammals] are way down in the Aleutians.”

While algal blooms are not uncommon in the Pacific, 2015’s blooms appear to be the largest on record, scientists say. Stretching from Southern California to Alaska, the blooms are responsible for unprecedented closures of fisheries and unusual deaths of marine life up and down the Pacific coast.

Pseudo-nitzchia is one species of algae that produces domoic acid, a neurotoxin that can be lethal to humans and wildlife. The toxin is ingested by shellfish and krill that, when consumed, pass the toxin onto the predator — in some cases, people.

Raphael Kudela, a professor of ocean sciences at the University of California, Santa Cruz, said climate change may be a factor enabling the blooms to thrive. “I think, personally, it’s quite possible that these warm conditions just set up the ideal incubator conditions for this organism. It’s doing really well and lasting a lot longer than usual.”

In California, researchers in Monterey Bay observed some of the highest levels of the toxin ever seen. Oregon’s Department of Agriculture has shut down recreational harvest of razor clams along much of its coast. In Washington, authorities instituted an unprecedented closure of the state’s lucrative Dungeness crab fisheries. A fishery near Vancouver was closed in June over concerns of the algae’s toxin, which can cause seizures and death if consumed by humans.

“In Monterey, things have kind of calmed down a bit,” said Kudela. “We have been monitoring several times a week now. We still see toxin, so it hasn’t gone away.”

He added that the bloom may have moved further offshore and deeper in the ocean.

The algae were detected in southeastern Alaska in June. The discovery of nearly a dozen dead whales in the Gulf of Alaska near Kodiak also raised suspicion.

A dead sea lion that washed up near Unalaska in the Aleutian Islands is what prompted the most recent round of testing, Unalaska’s community broadcast network KUCB reported. Other die-offs of species have been reported along the Aleutian chain, stretching nearly 1,500 miles across the north Pacific, 2,000 miles north of Seattle.

“The best thing to keep an eye on is if they keeping seeing it in Alaska,” Kudela said. “And that would be a pretty clear indication of if the bloom has extended.”

“There’s just not a lot of resources going into understanding these big algal blooms,” Wright said. “The government doesn’t spend a lot of money on it, and I think that’s a big mistake. And in the future I think that’s going to be a big mistake as waters continue to warm in the Gulf of Alaska and Bering Sea.”

Wright added: “[Algal blooms] have the potential of taking out fisheries.”

Late last month, the National Oceanic and Atmospheric Administration gave the state of Washington nearly $100,000 to continue to monitor the bloom.

Vera Trainer, a University of Washington researcher and manager of NOAA’s Harmful Algal Blooms Program, said expeditions are underway to try to map the bloom. What remains to be seen is whether or not there is one contiguous bloom, or several large ones.

“It does appear to be rather contiguous,” Trainer said. “What we’ve seen in past years is that we’ll have a bloom in California, and a little bit later in the year we’ll have a bloom in Washington. This one seemed to happen all at the same time.”

Kudela said researchers have found the toxin in anchovies and other fish. “We know that can happen, but generally the blooms don’t last long enough to see that transfer occur.” Trainer said that sea lions had never before been seen having seizures off the coast of Washington, a symptom of poisoning from the algae.

Research expeditions are underway along the Pacific coast and into the Gulf of Alaska to try to map the bloom. The last ship is due back in September, and Trainer expects a clearer picture of what exactly is happening by the end of the year.

Kudela said whether or not this year’s bloom is the “new normal” is “the million dollar question,” said.

“We could go into three years in a row of having really toxic algae out there and it getting into the food web,” he said.

Shellfish and other seafood are a staple in the diet of coastal communities up and down the Pacific coast, including many Native communities.

Wright, who has been studying toxic algal blooms since the 1970s, said many elders in Alaska Native communities have been alarmed by the increasing frequency of the toxic algae blooms, which threaten their traditional way of life.

“But those are the kinds of changes we’re going to see with climate change,” Wright said. “We’re going to have to change and adapt and we’re going to have to lose some of our traditions, and that’s just the way it is.”