In May, the Oregon Department of Fish and Wildlife received a tip that an unusual-looking crayfish was spotted in a creek around Lithia Park in Ashland. Biologists from the state agency laid out traps and confirmed the presence of Northern crayfish which are native to the Midwest. It marks the fourth invasive species of crayfish now found in Oregon waterways. Sampling conducted by ODFW scientists found that Northern crayfish had moved from the Ashland canal to Bear Creek near Medford, 15 miles away, and raised concerns that they could already be in the Rogue River. Rick Boatner is the invasive species coordinator for the Oregon Department of Fish and Wildlife. He shares with us how the aggressive crustaceans are proliferating in Southern Oregon and the threat they pose, not only to native Signal crayfish but also to endangered steelhead and salmon.
The following transcript was created by a computer and edited by a volunteer:
Dave Miller: From the Gert Boyle Studio at OPB, this is Think Out Loud. I’m Dave Miller. In May, the Oregon Department of Fish and Wildlife (ODFW) received a tip that an unusual looking crayfish was spotted in a creek near Lithia Park in Ashland. Biologists at the agency eventually confirmed that they were Northern crayfish which are native to the Midwest. They are the fourth species of invasive crayfish that’s been found in Oregon waterways. Now, biologists are concerned that they’ll spread further into the state, outcompeting Oregon’s only native crayfish. Rick Boatner is the Invasive Species Coordinator for ODFW, also the Chair of the Oregon Invasive Species Council. He joins us to talk about these crustaceans and more. Rick Boatner, welcome.
Rick Boatner: Thank you, Dave. Thank you for having me.
Miller: Thanks for joining us. Can you describe what these Northern crayfish look like?
Boatner: They’re about four to six inches long. The inside of their pincers look like little teeth. So they look pretty gnarly. And they’re fairly aggressive.
Miller: There are teeth inside their pincers?
Boatner: Well they look like teeth. They’re called tublicers but they’re used for crushing things.
Miller: How are they different from Oregon’s only native crayfish species which are called Signal crayfish?
Boatner: Well the Signal crayfish can be a little bit bigger. They also live a little longer than the non-natives. Our native species have a smooth claw and then between their pincers, right at the joint, they have a white patch and that’s how they got their name. They’re native all through Oregon and Washington.
Miller: So if folks see a smooth clawed crayfish that has a little white patch, then they can be assured that that is Oregon’s only native crayfish species?
Miller: What do the Northern crayfish eat? Are their lives and behaviors different from native crayfish?
Boatner: Well, crayfish in general, they’re opportunists. So they’ll eat anything pretty much they can grab. So that includes eating fish, eggs, tadpoles, small fish, invertebrates like snails and mayfly nymphs. So they’re kind of the clean up crew of the streams and rivers and lakes
Miller: For good and for ill, depending on whose side you’re on here saying in terms of steelhead or salmon. I’ve also heard that crayfish are cannibals. Is that true across the board?
Boatner: Yeah, they’ll cannibalize on each other. Our Signal crayfish is notorious for that. And a crayfish through when they grow, they basically walk out of their exoskeleton, their outside shell. And that’s when they’re most vulnerable to prey because they don’t have a hard shell to protect them. And that’s when they can be cannibalized on by other crayfish.
Miller: Would Northern crayfish prey on other species of crayfish?
Boatner: Yes, Northern [crayfish] and another one, the Rusty crayfish are very aggressive and they’ll prey on our native Signal crayfish, with no problem.
Miller: And that’s more likely than the other way around where the Signal crayfish, the native ones preying on the non-natives?
Miller: I noted that somebody called in a tip saying, ‘hey, I’ve, I’ve seen an odd looking crayfish near Ashland,’ back in the spring. Can you tell us that story of what happened after you got that call?
Boatner: Like you said, a person was walking along the creek and noticed these crayfish. Fortunately, her husband is also a biologist with the U. S. Forest Service and they know a professor at Southern Oregon University. So they took the crayfish to them and they identified it as the Northern crayfish and then reported it to us. After we got that information, we went down and did some sampling with crayfish traps in Ashland Creek and then we moved outside of Ashland Creek into Bear Creek. Ashland Creek is a tributary to Bear Creek. And we looked all the way down to the Medford area. And we found Northern crayfish all the way down almost into the Rogue River. So they were distributed farther than we were hoping for.
Miller: Because you were hoping for them to not be there at all?
Boatner: Well, we knew they were there, but we were hoping they were just in that small area and then we might have a chance to do something. But when they distributed over 15-20 miles of streams, it makes it pretty difficult to do anything.
Miller: How do you think Northern crayfish got into southwestern Oregon?
Boatner: Possibly it might have come through classrooms, which do a curriculum on crayfish, or in through fish bait with fishermen using them as bait for salmon or steelhead trout or the other, through the pet trade. So it’s kind of hard to come down with the exact reason they got there.
Miller: There’s a lot of different things you mentioned there. People have crayfish as pets?
Boatner: Yeah. And they are generally advertised as neon blue freshwater lobsters or something like that. But people keep them for pets sometimes.
Miller: And then the thinking would be that they get bored or tired or whatever and then just throw them out the back window and they end up in streams?
Boatner: Yep and a lot of them, especially in crayfish, they store the sperm. So you may have a crayfish that looks pretty innocent, but you put it in the water and it actually is a female that is holding eggs. In the spring she’ll release 200-800 eggs. So you get a population very quickly.
Miller: And what about the school hypothesis? How might invasive species of crayfish end up in Oregon or any other state because of schools?
Boatner: In schools, as part of their curriculum is studying crayfish. Some schools are really responsible and euthanize the animal after it’s done, others will release it into the water thinking their one or two crayfish are going to cause any harm
Miller: As if it’s the kind of thinking,’we’ll be kind and we won’t kill this animal?
Miller: Has that happened in any documented places in Oregon?
Boatner: Well, we believe the Rusty crayfish in the John Day Basin was started from a middle school release.
Miller: After something like that happens, what kinds of education campaigns do you do as the invasive species coordinator for the Oregon Department of Fish and Wildlife? I ask this because these are not people who are intentionally trying to muck up Oregon’s ecosystem, right.
Boatner: Crayfish are prohibited in Oregon. You need a permit to have them, even the schools. So we educate them through the permit process. We also use a brochure called ‘Don’t Let It Loose.’ And we work with that campaign. And Oregon Sea Grant also works in the school system for not letting critters from curriculum get loose. So we’re trying to educate them that way.
Miller: I want to go back to the surveys that you did in the spring after you’ve gotten the tip from folks that the Northern crayfish had been found near Ashland. When you found that particular invasive crayfish in various streams around there did you also find the Signal crayfish, Oregon’s native species?
Boatner: No, we didn’t pick up any native Signal crayfish. We did pick up the other two non- native species that are in southwest Oregon, the Red Swamp crayfish and the Ring crayfish.
Miller: Do you think that the fact that you found those other invasive crustaceans, but not the native species. I mean, is that causal?
Boatner: Yeah, I believe that that’s the reason the Signals aren’t there anymore. And you can see that in the John Day with the Rusty crayfish. It’s hard to find Signals any more unless you get outside of where they’re at.
Miller: And that goes back to the aggressiveness and opportunistic nature of these introduced crayfish that they’re just outcompeting the native species?
Miller: So let’s turn to what you could do about this. I mean, what would it take to get rid of a particular invasive species of crayfish in some particular basin?
Boatner: Well, it depends on where it’s found. Now, in the case of the Northern crayfish, it’s in the creek and a tributary of, eventually, the Rogue River. So there’s not a lot you can do with them once they’re so distributed because in a lot of our streams we have threatened and endangered salmon and steelhead. So that limits what you can do.
Miller: Why does the presence of endangered or threatened salmanites make it hard to get rid of crayfish?
Boatner: Because it limits the tools you can use. I mean, you might be able to use trapping, but that really is not going to eradicate them. But you can’t use chemicals or stuff like that in the water to eradicate crayfish because they’ll kill the salmon and steelhead and other salmanites, or whatever species are in the water.
Miller: And the trapping, you’re saying, is just not enough once these species are really established?
Boatner: When they’re really established, it’s very difficult. There’s only been a couple of cases in the nation where they’ve eradicated crayfish from a system and those are isolated water bodies, not a moving water type system.
Miller: So it really does seem like part of your job is not actually thinking about eradicating. You’re thinking more about mitigating or living with these species?
Boatner: At this point, it’s more of living with the species. Now we looked at the species, the Rusty crayfish. We did find them in the isolated water body in the Malheur basin. So we have been doing experimental chemical treatment of that water body to eliminate them and we’re almost there. But it’s difficult even with chemicals.
Miller: We’ve talked for 15 minutes and we haven’t talked about eating them yet, which is a glaring omission because these, I mean, these can be delicious. Are all of these different species, native and invasive all edible?
Boatner: Yes, the Northern and the Rusty are about the same size. Our Signals are a little bigger, but they all can be eaten. The Ringed are a little smaller. But yeah, they can be eaten too. You just don’t get much meat.
Miller: Can we eat our way out of this problem?
Boatner: Most likely not. I mean it would take a very intense trapping effort to remove them completely. And so I think it would be slim.
Miller: But I guess every one that Oregonians find and get rid of is not going to hurt?
Boatner: It’s not gonna hurt the landscape. Definitely won’t hurt it.
Miller: Do they taste different?
Boatner: The Signal and the Rusty and the Northern. I have not found any difference. I haven’t eaten the Northern yet. But the Rusty and the Signal and I can’t tell any difference. But everybody has their preference. I guess.
Miller: Rick Boatner, it was a pleasure talking to you. Thanks very much for your time.
Boatner: Thank you, Dave. Have a great day.
Miller: He is the chair of the Oregon Invasive Species Council and the invasive species coordinator for the Oregon Department of Fish and Wildlife. He was talking to us about the number of invasive crayfish species that are now in Oregon and that are outcompeting Oregon’s native crayfish.
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