View Details

Louisiana crawfish caught in waters in and around Berlin are on display at Fisch Frank fish restaurant in Berlin. They are an invasive species and authorities recently licensed a local fisherman to catch them and sell them to local restaurants.

Carsten Koall / Getty Images

In a shaded stream in the middle of Berlin's rambling Tiergarten park, fisherman Klaus Hidde lowered himself into the water recently. Several children stood on a platform above him and watched him wade in, wearing high rubber overalls. Hidde pulled a netted trap out of the water and shook it in the air.

"There's too few," Hidde says, shaking his head.

Hidde and his son are the only people licensed to catch thousands of Louisiana crawfish that have invaded the waters of two parks in Berlin. The goal is to solve the problem by selling the catch to chefs and businesses. But on this day, there are a scant 100 crawfish between three nets.

"They're not even a hundredth of a percent" of the solution to the problem, Hidde says, as he shakes the dark red crustaceans into a black bin.

This is the third year Louisiana crawfish have been seen in Berlin. City wildlife officer Derk Ehlert says when crawfish first appeared, the city released eels into the waterways, hoping they'd catch the crawfish and eat them. But then the next year, there were still 3,000 crawfish in the parks. This year there are 10 times as many and they seem to be spreading. At one point, hundreds of crawfish clambered out of the lake and ambled along the Tiergarten's shaded paths.

"It's normal for them but [ab]normal for the people in Germany," Ehlert says.

Crawfish are not entirely foreign to Germany. But the Louisiana crawfish, Procambarus clarkia, crowd out the native Astacus astacus European variety and carry a disease that kills them, Ehlert says.

"The home animals and plants must be saved," he says.

Louisiana crawfish have become a familiar problem elsewhere in the world, too: They have scarfed down freshwater fish and other animals in Egypt, Kenya and South Africa. They turned up in Michigan. And a species of Washington State crawfish threatens trout in Scotland. There, authorities caught and killed the crawfish, to avoid creating a market for them.

Berlin's experiment with eating the invasive crawfish is still a work in progress. To the west of the Tiergarten, in the Spandau borough, Olaf Pelz cracked the shell of one of Hidde's red crawfish in his restaurant, called Fisch Frank. Across town, the trendy Markthalle Neun food market hosted a Louisiana-style crab boil in mid-July, cooking the crawfish in a piquant broth and serving them on trays with corn and potatoes. But Pelz said most of his customers are older and prefer a simple recipe.

"When we serve it here we make it with salad and bread and typical sauce," he says. He puts dollops of mayonnaise and cocktail sauce on the plate, and tops the crawfish with a thin slice of lemon.

Despite his efforts, customers are skeptical. Erika Klugert rises from her outdoor table to watch Pelz uncover the soft tail meat of the crawfish.

"This food requires too much work," Klugert says. She says she just ordered shrimp from Pelz and ate it. And it was much easier. "Without a shell, but it was delicious."

Hidde, the fisherman, notes another challenge: matching supply with demand. When he caught thousands of crawfish earlier this year, he says he struggled to find buyers. In late July he got an order for about 100 pounds of crawfish, but he could only find a few of the creatures in the one stream he checked in the Tiergarten. He guessed the rest were hiding from a Berlin heat wave.

"It gets on your nerves," he says of the uncertainties he faces on the job. "I raise expectations with people for a lot of crawfish, and I can't always fulfill them." He says he has about 25 traps strung across the Tiergarten and Britzer Garten, and hopes some of the others might help make up the order.

He has also bought a few more days of flexibility by using a swimming pool in his backyard as a holding tank.

Hidde acknowledges it may be impossible to clear all the invasive crawfish out of the waters of the two parks he has targeted. He finds five Louisiana crawfish for every Berlin crustacean, he says.

"There are so many that the effect is very small," he said. "It's like a hamster race."

Still, he says, he hopes his culinary fishing mission might at least hold the line and protect the rest of Germany's waters.

Copyright 2018 NPR. To see more, visit http://www.npr.org/.

Story does not include AP content

food #news #business #world #science #europe #environment #germany #berlin #louisiana #invasive species #crayfish #crawfish

World News Science Environment Normal Tweet

View Details

Signal crayfish in Lake Washington in Gene Coulon. This crayfish has several branchiobdellida annelida attached to it.

Roger Tabor

SciWorks Radio is a production of 88.5 WFDD and SciWorks, the Science Center and Environmental Park of Forsyth County, located in Winston-Salem.

I love Cajun cooking. There’s nothing like a gumbo crawling with crawdads! While this thought may bring you back to the bayou, the Southeast – and North Carolina especially – is where it’s at if you’re a crayfish.

The center of biodiversity for crayfish is in the Southeastern United States, so we have the highest diversity of crayfishes worldwide. North Carolina itself has coming up on 50 known species of crayfishes, but there are still several in the state of North Carolina that have yet to be described, which I think is very exciting.

That’s Dr. Bronwyn Williams, Research Curator of Crustaceans at the North Carolina Museum of Natural Sciences.

In general, North Carolina is among the most biologically-diverse states, for several reasons that have previously been discussed here on SciWorks Radio.

RELATED: Diversity of Species in North Carolina​

Along with that, there are a couple of thoughts as to why we we live in the the Mudbug Mecca.

You have one hypothesis: that this is the center of origin and then there was dispersal out. The other one is because they haven’t been cyclically wiped out by these huge, massive glaciers coming down and running everything off, and they have to recolonize again.

In a way, crayfish are islands unto themselves, kinda. Most species carry with them Branchiobdellida, a species of worm that live life on the clawed critter. Check them out in this video:

Dr. Williams sees the worms as an opportunity.

Can we use these species of worms to actually track or better understand the relationships among crayfish? Or interactions among crayfish?

To better understand a relatively quick, 125-mile upstream migration of a crayfish population, Dr. Williams hypothesized that the worms’ short life-cycle would give a fine-scale resolution of the migration pattern.

So, with the crayfish, we found a fair bit of variation that fit to the landscape very well, but the worms we found nothing. Everybody from Alberta to Ontario and Minnesota shared that same sequence.

Meaning there was none of the mitochondrial variation you would expect after many generations of worm reproduction.

It was just jaw-dropping. Yeah. No idea.

The crayfish host an integrated society; the worms share the neighborhood with a smaller species called ostracods, or seed shrimp.

The largest ones are about a half-a-millimeter in length, and they just look like little kidney beans with legs and antennae. As one of my interns says, they’re microscopically adorable!

Both of these groups would be what we would call obligate ectosymbionts of these crayfishes so, they are obligated to live on that host in some way, shape, or form.

Interestingly, neither the worms nor the seed shrimp actually feed on the crayfish; rather it’s the best neighborhood to raise a family.

When they lay their eggs, those embryos actually won’t develop unless they’re actually on a live crayfish, which is wacky. But nobody has been able, in a lab situation, to rear these off of a live crayfish host. So it’s some sort of uptake, some need from that live crayfish that they get to sustain those embryos.

So, you have these two completely different groups; these little arthropods, these little crustaceans and these worms, that have adopted this very similar, kind of needy lifestyle, as it were.

The highest species diversity that I’ve seen is six different species of worm on a single crayfish, and two species of these little ostracods, so eight total symbiont species on a single crayfish. And they do seem to have their own little territories for the most part. They seem to partition out. You know, “I’m going to claim between the eyes, and you’re going to go down on the tail,” and so on and so forth. They’ve got these territories worked out.

They perceive the crayfish as a landscape. You go out and log at the various buildings and the hills and so on and so forth. To them, that’s the “I’m going to plant my house here on this crayfish.”

This Time Round, the theme music for SciWorks Radio, appears as a generous contribution by the band Storyman and courtesy of UFOmusic.com.

science #biology #crayfish #crawdads #mudbugs #north carolina museum of natural sciences #branchiobdellida #ostracods #dr. bronwyn williams #duke #dna #molecular #genes #chromosome #dr. beth sullivan

Science Normal Tweet

View Details

In the northwestern United States, this crayfish would be just a friendly bit of local fauna. But in Scotland, it's an invasive species wreaking havoc on trout streams.

Ari Shapiro / NPR

Forget Nessie: there's another insidious creature living in the waters of Scotland.

The story starts in the streams and lakes of the northwestern United States, where North American signal crayfish are a familiar sight. Turn over a rock and you may well encounter one.

But in Scottish streams and lochs, these creatures are intruders.

In the United States, we often hear about invasive Asian carp, zebra mussels or snakehead fish from China that take over American waterways. It's a two-way street: American species are causing chaos in other parts of the world, too.

And in Scottish waters, home to prize-winning trout, American crayfish may be destroying the catch.

'Hundreds And Hundreds And Hundreds Of Them'

Allen Pleus, with the Department of Fish and Wildlife in Washington State, says that the signal crayfish is an important species in his region. It's the only native crayfish species, and the freshwater crustaceans are are just another part of the ecosystem.

"They play well with others," he says. "They've learned to be good neighbors with the other native species."

They eat aquatic insects and larvae; raccoons and herons, in turn, eat them. The system works.

But those same crayfish wreak havoc in Scottish waters like Clyde's Burn — a stream in Scotland where anglers from all over the world come to fish.

Matt Mitchell has been casting his line into these waters for about 40 years. "This area is probably, if not the best, certainly one of the best trout fisheries in the world," he says.

One day Mitchell got a call from an angler friend. The conversation changed Mitchell's life.

"He phoned me and said, 'I think we have a problem. You'd better come look at this,' " Mitchell says.

He jumped in the car and headed to the river.

"I could not believe the number of crayfish that were in this part of the river," he says. "You could literally walk across the river standing on crayfish. You couldn't walk without standing on a crayfish, they were so numerous!"

The North American signal crayfish, which had been introduced to English waters decades ago and spread steadily north, were taking over.

"What we did initially was just hand-catch them," Mitchell says, "hundreds and hundreds and hundreds of them."

There was some pinching involved. "I'll not repeat what the language was like," Mitchell says. "But they were big animals. I mean, some of these things were about 10, 12 inches long."

At that size, they don't even look like crayfish; they look like lobsters. Animals that big, Mitchell says, are more than a decade old; he guesses they've been in the river for 12 years.

No Trout Food, No Trout

The problem isn't just the size or quantity of the intruders; it's that the signal crayfish eat the same insects and larvae as the prize-winning trout that are native to these streams.

Mitchell's colleague Ian Miller is the man who first placed that concerned phone call from the Clyde Burn all those years ago; Mitchell calls him the best Clyde angler alive.

With the arrival of the crayfish, Miller says, "Stoneflies are gone — basically wiped off the face of the Earth."

That's a problem, because stoneflies are an important food for the fish. No trout food means no trout.

At the river, Miller pulls up a trap from the water to demonstrate. The plastic cage is alive with crawling, clacking crayfish — about a dozen of them, dark reddish-brown with giant claws, climbing all over each other inside the trap.

Crayfish like these can be a delicacy, but Scotland has decided that encouraging people to eat them would just create a market and make people spread them more widely.

As a result, anyone who pulls crayfish out of a Scottish river is legally required to kill them. The quickest way, Ian says, is to stomp them beneath a boot.

Fighting Invaders In Home Territory

Allen Pleus, the naturalist back in the Pacific Northwest, commiserates with the Scottish anglers.

Turns out, Washington State is struggling with a similar problem.

"Unfortunately, we now have our own invasive-species crayfish in this area — mostly red swamp crayfish from the southern United States," he says.

That's right. At the same time that the North American signal crayfish are taking over rivers and streams in Scotland, they're being crowded out of rivers and streams in their native habitat by other invasive crayfish — interlopers from Louisiana.

And those signal crayfish that are dominating streams in Scotland? In America, Pleus says, "They're considered wimpy in some cases — that they don't put up enough of a fight with these non-native species."

The serpent — or in this case, the crayfish — eats its tail.

Copyright 2015 NPR. To see more, visit http://www.npr.org/.

Transcript

ARI SHAPIRO, HOST:

Now we have a real-life fish tale about an insidious creature living in the waters of Scotland. And we're not talking about Nessie. This story actually begins in the United States.

Years ago, when I was a kid in Portland, Oregon, my brothers and I would go to nearby Fanno Creek. We'd turn over rocks or lower a piece of raw meat on a string into the water. And we'd pull out a crayfish - specifically a North American Signal Crayfish.

ALLEN PLEUS: They're important species in our streams and lakes. They are the only native crayfish that we have.

SHAPIRO: Allen Pleus is at the Department of Fish and Wildlife in nearby Washington state. He's very familiar with this species of freshwater crustacean.

PLEUS: They play well with others. They've learned to be good neighbors with the other native species.

SHAPIRO: So I would imagine that raccoons and herons eat them. They eat aquatic insects and larva and everyone lives happily ever after until they get eaten by someone else.

PLEUS: That's a good way to say it. Yeah, it's part of that system.

SHAPIRO: I never imagined that as an adult, I would find those same creatures wreaking havoc in Scottish waters.

MATT MITCHELL: This area is probably - if not the best - certainly one of the best trout fisheries in the world.

SHAPIRO: We're standing next to stream called Clyde's Burn. Anglers come from all over the world to fish here. Matt Mitchell has been casting his line into these waters for about 40 years. One day he got call from an angler friend that literally changed his life.

MITCHELL: He phoned me and said I think we have a problem. You better come up and look at this.

SHAPIRO: Mitchell jumped into the car and headed to the river.

MITCHELL: I couldn't believe it myself. I could not believe the number crayfish that were in this part of the river.

SHAPIRO: What did you see?

MITCHELL: I mean, you can literally walk across the river standing in crayfish. You couldn't walk without standing on a crayfish. They were so numerous.

SHAPIRO: These were not just any crayfish. The North American Signal Crayfish were taking over. They had been introduced to English waters decades ago and spread steadily north. And these guys were big.

MITCHELL: What we did initially was just hand catch them - hundreds and hundreds and hundreds of them.

SHAPIRO: Did you get pinched?

MITCHELL: Oh, initially, of course you did. (Laughter) I'm not going to repeat what the language was like. But they were big animals. I mean, some of these things were about 10 inches, 12 inches long.

SHAPIRO: That's a lobster. That's not a crayfish, that's a lobster.

MITCHELL: That's a big animal. That's an animal that's about, you know, 10, 12 years old. They've been in our rivers for about 12 years we reckon.

SHAPIRO: In the United States, we often hear about invasive asiatic carp, zebra mussels, or snakehead fish from China that take over American waterways. Turns out it's a two-way street. American species are causing chaos in other parts of the world too. In Scotland, the North American Signal Crayfish eat the same insects and larva as the prize-winning trout that are native to these streams.

MITCHELL: Here's a friend and colleagues of mine, Ian.

SHAPIRO: Hi, Ian. I'm Ari. Nice to meet you. Welcome.

IAN MILLER: Hi. Hi.

SHAPIRO: Ian Miller is the man who placed that you'd better get over here phone call from Clyde's Burn all those years ago.

MITCHELL: I would say Ian is the best Clyde angler living at the moment, by far.

SHAPIRO: And what kind of changes have you seen with the arrival of the crayfish?

MILLER: Stoneflies are gone - basically wiped off the face of the earth.

SHAPIRO: And that's an important food for the trout.

MILLER: That's an important food.

SHAPIRO: No trout food means no trout. The night before we met him, Ian Miller dropped a couple of traps in the water using a dead fish for bait. As we peered over the banks, he pulled the first plastic cage out of the stream. It was alive with crawling, clacking crayfish.

MITCHELL: A dozen or more crayfish in it.

SHAPIRO: Oh, my God. They're huge. Oh, there's - yeah, there's, like, a dozen of them climbing all over each other. They're beautiful. I mean, they've got these enormous claws. They're dark reddish brown with a hint of blue at the joint of the claw.

Crayfish can be a delicacy. But Scotland has decided that encouraging people to eat them would just create a market and make people spread them more widely. So anyone who pulls crayfish out of a Scottish River is legally required to eliminate them.

So these now have to be killed having been removed from the river. How will you do that?

MITCHELL: Under my boot.

SHAPIRO: Really?

MITCHELL: That's the quickest and convenient way.

SHAPIRO: All right, well, with apologies to any squeamish listeners, let's get the sound of this.

I described this scene to Allen Pleus, the naturalist back in the Pacific Northwest. He commiserated with the Scottish anglers. Turns out, Washington state is struggling with a similar problem.

PLEUS: Unfortunately, we now have our own invasive crayfish species in this area - mostly Red Swamp Crayfish from the southern United States.

SHAPIRO: Wait a minute. I'm doing a story about the North American Signal Crayfish taking over rivers and streams in Scotland. And you're telling me they are being crowded out of rivers and streams in their native habitat by other invasive crayfish that have been brought in from Louisiana?

PLEUS: Yes. The native Signal Crayfish - they're considered wimpy in some cases - that they don't put up enough of a fight with these non-native species.

SHAPIRO: The serpent eats its tail - or in this case, the crayfish. This is WEEKEND EDITION from NPR News. Rachel Martin is back next week. I'm Ari Shapiro. Transcript provided by NPR, Copyright NPR.

world #science #europe #animals #united states #world story of the day #trout #scotland #crayfish

World News Science Normal Tweet