Biotoxin affects shellfish harvesting in Oregon, Washington

The Oregon Department of Fish and Wildlife and the Oregon Department of Agriculture recently announced the closure of mussel harvesting throughout the entire Oregon coast. The agencies also announced closures for razor and bay clam harvesting along parts of the Oregon coast.

In Washington, officials have also closed recreational harvesting for some shellfish, including clams, oysters and mussels.

Agencies are checking for a marine biotoxin which can cause paralytic shellfish poisoning. The naturally occurring biotoxin affects the nervous system. People with paralytic shellfish poisoning can experience tingling of the lips and tongue, nausea and difficulty breathing.

The illness has been linked to the sickening of at least 21 people in Oregon last month. The Oregon Health Authority is also asking people who recently harvested or ate any shellfish from the Oregon Coast to complete a survey. Officials are investigating illnesses linked to contaminated shellfish.

We learn more about biotoxins and how climate change might be affecting algae that produce them from Vera Trainer, the marine program manager of the University of Washington’s Olympic Natural Resources Center.

Note: This transcript was computer generated and edited by a volunteer.

Dave Miller: This is Think Out Loud on OPB. I’m Dave Miller. At least 21 people were sickened last month after eating mussels that they harvested from Oregon’s North coast. They were victims of a marine toxin that causes paralytic shellfish poisoning. As a result, the state has closed recreational mussel harvesting on the entire coast. There are also partial closures of razor and bay clam fishing. Washington officials have closed all recreational clam, oyster, and mussel harvesting up and down the state’s Pacific Coast.

For more on this toxic outbreak, we called up Vera Trainer, the marine program manager of the University of Washington’s Olympic Natural Resources Center. I started by asking her how this toxin affects the human body.

Vera Trainer: Paralytic shellfish poisoning affects your nervous system. The toxin produced in paralytic shellfish poisoning syndrome is called saxitoxin. And, as we know, there’s the flow of ions through nerves that allows all your movement throughout your body. Well, these saxitoxin that are found in the paralytic shellfish poisoning, they act very much like a cork on a bottle, where they block the flow of ions into sodium channels of nerves. And the result in people is tingling of hands and fingers and sometimes lips, and ultimately it leads to paralysis and even death. Thus, the name paralytic shellfish poisoning.

Miller: The first symptoms are likely that tingling sensation in lips or extremities?

Trainer: Correct. And even harvesting highly toxic shellfish, you can have that tingling of your fingers when you harvest them.

Miller: You mean even if you don’t eat them?

Trainer: Correct. The poison is water soluble, the saxitoxin is water soluble, so it can even go past your skin to the nerves in your fingers and cause that tingling sensation.

Miller: How is it treated?

Trainer: Pretty much just supportive care. If by chance you do get this poisoning, you should seek medical attention as soon as possible, and doctors will put you … well, I think there’s actually one person in Oregon who was put on intubation and given fluids. But recovery is usually pretty quick.

Miller: If you recover. But how deadly is it?

Trainer: It’s highly deadly. It was even used as a nerve agent, way back when, by the US military. No longer is that the case, but there are people who have died around the world, including in Alaska. And folks have become sickened in Washington, and now Oregon, and also California. So it’s a poison that is not uncommon on these coastlines, but it’s relatively well-managed by our health departments.

Miller: I want to turn to that in just a second, in terms of how it’s managed and monitored. But just to go back to the kind of news we could all use in case, say, at some point in the future, we harvest mussels somewhere on the Oregon or Washington Coast, and have tingling fingers. Am I right … on the Washington website it says that basically, if you start to feel that way, you should take syrup of ipecac and a serious laxative as soon as possible. Is the idea to get this all out of your system as quickly as you can?

Trainer: Yeah. I would highly recommend seeking medical attention. I’m not a physician, so I don’t want to give medical advice. But I really think the best is to get to an Urgent Care or a hospital as soon as possible and let them know you think you ate toxic shellfish. They will know what to do.

Miller: Now, where does this toxin come from?

Trainer: Some very powerful microscopic organisms that live in the ocean. These are invisible to the naked eye, single-celled organisms, that are making these toxins that just so happen to be poisonous to people. These plankton that live in the sea, that are free floating, they are not making these to poison people. But when shellfish feed on the variety of plankton in the ocean, most of which are not harmful at all, some of which are highly toxic produce these poisons or toxins that can then concentrate in the flesh of shellfish which, when we eat, we can become sick or even die.

Miller: So the muscles of mussels or clams, I should say the nervous systems of these shellfish, they’re not affected the way humans are?

Trainer: That’s a really great question. I was really interested in that in my career. And what we found, at least for one species of shellfish, is that they have developed a resistance in their nervous system. There is a mutation in their sodium channel that allows them to be highly resistant to these toxins. Because the great question is why are these clams, why are these shellfish not dying? And I think that’s the case, at least in this one species. And I think with more research, we’re going to find others that are resistant.

Miller: My understanding is that there are European histories of reports of this exact poisoning, paralytic shellfish poisoning, going back 300 years or more. And that there are Native stories going back further than that. Is there anything new about these outbreaks?

Trainer: They’re naturally occurring events. And in fact, as you mentioned, in the late 1700′s, when Captain George Vancouver was exploring our waters, one of the members of his crew, John Carter, became sick and died. And there is Poison Cove in Canada that’s actually named after this event.

What we know is that these cells, these plankton, some can form cysts, very much like seeds, in the sediment of the sea. So when there is a harmful algal bloom, as we have just experienced, these cysts can then spread to other regions, most often enclosed embayments where they can cause blooms in future years. So I would expect now, with this event, these occurrences are going to become more common.

Miller: Is there a connection between climate change or ocean acidification, or warming ocean waters, and these blooms and these outbreaks?

Trainer: That’s the million dollar question. But I would say that, with warming waters especially, we’re gonna be seeing a longer window of opportunity in which these cells can thrive. So, very much like your dandelions bloom on your lawn, with warmer temperatures, they’re gonna bloom earlier in the season. By having these warmer temperatures, we create an opportunity for these cells to do really well. So that’s one example.

As far as ocean acidification or other factors, there’s a coastwide study, a multi-stressor study, that’s looking at this very thing right now. But it’s tricky to look at this multitude of factors and say, “Oh, it’s this one thing, or it’s this other thing that’s causing these blooms to become more intense.” I think for sure with increased temperatures, we’re going to see longer durations during which these blooms can thrive. And we’re going to potentially see more intense events like we’re observing now on the west coast. It’s not just Oregon but Washington that is seeing these blooms.

Miller: How much can this toxin be tracked?

Trainer: As I mentioned, these are microscopic organisms that occur naturally in coastal seawaters, so if you are able to collect a seawater sample and look in a microscope, you’re able to observe these cells. The organism’s name is Alexandrium, and it looks very much like a chain of hamburgers, so it’s pretty easily recognizable. It’s a swimming cell, so it’s also gonna move.

The challenge is that some of these cells originate from offshore. So we need boats, or we need autonomous vehicles to go out and collect samples and to tell us whether they are offshore in the coastal ocean. Then models can be used to track their movement onshore. All of this, as you can imagine, is quite expensive. But I would say that the beach monitoring is relatively easy, straightforward, and doesn’t require a huge amount of funding.

Miller: How much monitoring is happening in Washington? Can you describe the system that’s in place there?

Trainer: Through the Olympic Region Harmful Algal Bloom Partnership, which we call ORHAB, we have folks going out at least once a week and sampling, I would say, every 50 miles of coastline. They look in their microscopes to see whether harmful cells are present. If they are, then they can do rapid tests, much like you would do a COVID test or a flu test, to see whether or not these cells are toxic, and how toxic they are.

With these rapid tests, these rapid analyses, we can then partner with the health departments who are monitoring shellfish safety. But we need to have this stepwise progression, from the cells to the toxins in the water, to the toxins in the shellfish. So by looking at the water, we can give an early warning to the health departments who are monitoring the shellfish. And that’s the beauty of programs like ORHAB.

There’s also a program in Oregon called MOCHA, Monitoring Oregon’s Coast for Harmful Algae, which is currently seeking funding and is underfunded, and did not have the monitoring of the water in place because they’re between specialists. So I think that’s part of the reason why there wasn’t an early enough warning for this particular event. At no fault of the state agencies, but just illustrating that it’s super important to have the monitoring of the seawater in place.

Miller: In other words, we never know, it’s possible that if there had been a monitor in place, actually checking water regularly, more than 20 Oregonians or 20 people, after eating shellfish in Oregon, might not have gotten sick?

Trainer: Well, we might have known in advance that this bloom was coming and Fish and Wildlife could have put out the alerts to the public to say, “Hey, we’re approaching a bloom, do not harvest shellfish.” And that’s exactly what happened in Washington, I think last week. There were folks out on the beaches saying “Do not harvest shellfish.” And I was told that there were folks with buckets of shellfish in Washington, and the Health Department Specialist said “You might not want to eat them.” So the more folks with eyes on the coast and eyes at the beaches, the less chance of any illness occurring.

Miller: How long, in general, do these blooms last?

Trainer: That’s a really good question. It depends a lot on the weather and the coastal currents, as to whether or not the blooms get washed away. So if you have beautiful weather, quiescent conditions, nice sunshine, they’re going to last for a few days. But you need a balance, also, of storms that resupply nutrients to the coastal areas to fuel these blooms. So, I would say a week or two is common, then they start to dissipate.

Miller: But, if these toxins are already inside the flesh of mussels or clams, I imagine that that shellfish is going to be toxic for some time to come, even after the stuff they’re eating is no longer there.

Trainer: Yeah, that’s a really good point. And that’s the reason why you don’t want to eat shellfish, even if  you think “oh, maybe these … " – don’t try to predict on your own, because it really is very difficult to predict. And you’re right, that it takes a period of time, sometimes several weeks or even longer. There’s one, the razor clams in Washington and Oregon, who are subjected to a different type of harmful algal toxin, they can take more than a year to release all the toxins from their flesh. So, yeah, even if the cells are gone, doesn’t mean the toxins are gone from the shellfish.

Miller: The closures that prompted this conversation, they’re about, if I’m not mistaken, recreational fisheries. But, how is monitoring for commercial fisheries, which really account for, just way, way more of the shellfish that we’re all eating, or that people are eating, how does that monitoring work? And is it the same system?

Trainer: Yeah, I would say that every lot, every batch, of shellfish has to be tested. And I think that there’s really a prioritization of the commercial fisheries to ensure that they are safe so when you go to the market, you can be assured that there isn’t going to be a problem with your shellfish. There’s a very rare occasion when a recall is enacted for commercial fisheries. But a lot of times the recreational fisheries are protected because they’re close to a commercial fishery. But I truly believe more work needs to be done with the rec fishery, including having this plankton monitoring, that will just add that layer of security to the safety of the recreational harvests.

Miller: Vera Trainer, thanks very much.

Trainer: Oh, you’re very welcome.

Miller: Vera Trainer is the director of the Olympic Region Harmful Algal Bloom Partnership and the marine program manager at the University of Washington’s Olympic Natural Resources Center.

We spoke on Friday, the same day the Oregon Health Authority announced they want anyone who harvested or ate Oregon shellfish since May 13th to take a short survey. There is a link to that survey on our website: opb.org/thinkoutloud.

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