Algal blooms, fueled by warmer Northwest waters, create toxic recipe for coastal shellfish

Lurking within the deep, blue waters that lap along the Washington state coastline and into the Puget Sound, algal blooms burst in colorful explosions when the sun shines across the surface, giving these aquatic plants life.

But these brightly colored blooms sometimes pack a dangerous punch.

It’s been an active year for toxic algal blooms within Washington’s waters. The Washington State Department of Health has detected paralytic shellfish poison in many of the state’s marine areas. That’s a naturally occurring marine biotoxin that’s produced by some algae. The toxin enters shellfish when they consume the algae. When humans consume that shellfish, they can get sick with this serious poison, which can be fatal.

Many counties have recently closed recreational shellfish harvest, as ordered by the health department. More county closures could be on the way, said Jerry Borchert, who is the marine biotoxin lead with the department.

“What I’m seeing right now is concerning in that it’s starting to move south — Kitsap County, King County are likely to go next based on what I’m seeing,” Borchert said.

The Department of Health’s Public Health Lab has said they haven’t tested this many shellfish samples for biotoxins in the first half of the year since 2016.

The department is getting multiple alerts from partner organizations that test phytoplankton in the marine waters, Borchert said, which leads them to do more frequent shellfish testing and notify potentially impacted groups.

This map from the department of health shows where shellfish harvest is allowed and not allowed. From Whatcom County, San Juan County, Clallam County, Island County, Skagit County, Snohomish County to Jefferson County, there are a lot of closures.

“We’re in the peak environmental conditions for these events to happen. We’ve got warm water, we’ve got calm weather,” Borchert said. “The conditions are more favorable for toxic algae, if it’s present, to grow rapidly, and that’s what’s happening in multiple areas right now.”

Borchert, who has been with the department for decades, said this year has been more active than those in years past.

A particularly unusual event happened in May, when a type of algae called Alexandrium bloomed. That algae traveled up from the Oregon coast into Washington, and shut down commercial shellfish operations there.

“We sent the samples in that morning, and by that afternoon we had gotten calls that everything was going to be shut down,” said Kathleen Nisbet Moncy, who is the chief operating officer of Goose Point Oysters in Willapa Bay. “It was a very fast onset of this (paralytic shellfish poisoning) bloom.”

The algal bloom had a real impact on coastal shellfish growers like Nisbet Moncy. She is also the president of the Willapa-Grays Harbor Oyster Growers’ Association, and said growers in the region estimate about $1 million worth of product was lost due to recalls or being destroyed on-site because of the toxic outbreak.

“Mind you, this was on Memorial Day weekend, it was the weekend before graduation of our local schools as well, and farmers and processors here had no idea when their businesses were going to open back up,” Nisbet Moncy said.

Events like these are becoming more common. Borchert said recently, there’s been biotoxin closures every month of the year. Winter closures used to be unheard of. That leads to more costs for the department. Borchert said the agency is looking into cost saving methods to still test and ensure the products are safe.

“How do we do this and save some money and still maintain the same level of safety that we’ve always provided for Washingtonians and anybody who comes to visit here and eats shellfish?” Borchert said. “Everything is on the table.”

One way the health department keeps on top of testing is by keeping over 100 mussel sites scattered along the coast, coastal bays and Puget Sound for testing during the summer.

Mussels pick up toxic algae faster than other species, Borchert said. The department tests these mussel sites every two weeks, increasing frequency if toxins are detected. There are also organizations that do phytoplankton testing from water samples to look for toxic algae.

If, during testing, levels start to approach the limit, which is 80 micrograms of toxin per 100 grams of meat, growers have to send in samples of their harvest for testing before it can be sold.

When the algal bloom broke out on the coast in May, it was the health department and the Washington Department of Fish and Wildlife who notified growers.

Luckily, there were no illnesses in Washington from any commercial product with the late spring outbreak, thanks to careful coordination and testing by growers, the health department and Fish and Wildlife.

There have been Alexandrium blooms in the region in the past, Nisbet Moncy said, but there hasn’t been an event like this with paralytic shellfish poison uptake in shellfish since 1997.

Algal blooms certainly occur and state agencies will begin to see toxins in mussels, but it’s rare that these get into popular species for consumption like oysters and manila clams.

“In most cases, we never see toxin in commercial shellfish,” Borchert said.

While the spring event was unexpected, with climate change, the conditions that caused it are happening more often.

The state is not prepared for coastal growers to have these problems, Nisbet Moncy said.

“One of our biggest takeaways as growers is, first off, our labs aren’t set up for the coastal estuaries to go down or to have any issues,” Nisbet Moncy said.

With the sheer number of growers impacted on the coastline, the labs that sample shellfish for the toxin were overwhelmed, Nisbet Moncy said. The same problem was also occurring in Oregon. There wasn’t enough supplies to test that amount of sampling.

Borchert said the department had to focus on testing commercial samples first because of the supply shortage. While they continued to screen all samples, the department had to prioritize the testing for the areas they knew were most impacted.

Things opened up on the coast in July for commercial harvest. Washington coastlines are closed for sport harvest during the summer because of the high likelihood of a toxic event.

“Right now we’re more into the thick of really harmful algal bloom season,” Borchert said. “We’re starting to see a lot of toxin throughout the state in Puget Sound.”

While recreational harvesting is closed across much of the marine waters, it is still safe to buy shellfish from commercial operations.

Commercial harvest is regulated more strictly than recreational harvest to ensure businesses can continue operating and provide safe products to consumers. These growers have certifications with the state health department to continuously test shellfish beds for paralytic shellfish poisoning and other toxins, said Bill Dewey, the director of public affairs for Taylor Shellfish Farms.

For example, Dewey got a call this week from the health department that the lowest levels of toxin had been detected in some oysters in Samish Bay. In response, all commercial species from all beds being harvested in Samish Bay will be tested before any are sent to market.

As climate change makes harmful algal blooms more likely, bigger companies that have shellfish beds in numerous waterways will be better positioned to stay afloat. For example, the Taylor Shellfish Farms has shellfish beds all around the state. That helps because if one waterway is closed because of toxic outbreaks, the company can harvest from its other beds, Dewey said.

To be able to respond in years to come, Nisbet Moncy said the region needs more resources to monitor for harmful algal blooms.

The state Department of Fish and Wildlife, the health department and the National Oceanic and Atmospheric Administration are working with growers on the coast to get more predictive information and emergency plans in place.