Boom of invasive crayfish threaten species in Oregon’s Crater Lake

At Crater Lake National Park in Oregon, the site of the deepest lake in the country, the surface water temperature has been heating in recent years, attracting an invasive species of crayfish that is putting the lake’s clarity and native creatures in jeopardy. Correspondent Jes Burns of Oregon Public Broadcasting and EarthFix reports.

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  • MARK BUKTENICA:

    "Good candidate, perfect rock, but no salamanders."

  • JES BURNS:

    Biologist Mark Buktenica is scouring the shoreline of Crater Lake.

    Flying ants, lizards, and small toads are everywhere.

  • MARK BUKTENICA:

    "Aren't they cute?"

  • JES BURNS:

    But the critter he's looking for is much more elusive.

    Then his persistence pays off. This is the Mazama newt.

  • MARK BUKTENICA:

    "The Mazama newt found no place else in the world."

  • JES BURNS:

    Crater Lake formed nearly 8,000 years ago, after Mt. Mazama erupted and the caldera began filling with rainwater.

  • MARK BUKTENICA:

    "We don't know when newts entered the caldera but some time thousands of years ago."

  • JES BURNS:

    There were no fish or other predators in the newly-formed lake. And the Mazama newt expanded and thrived. It was the undisputed top of the food chain.

    But not anymore. Because crawling beneath the surface of the lake… A new champion has emerged. The signal crayfish.

    Their story begins more than 100 years ago. Back when getting to Crater Lake from Medford took five days by horse and wagon.

    To attract visitors early conservationists began stocking the lake with game fish like trout and salmon.

    Craig Ackerman is Park Superintendent.

  • CRAIG ACKERMAN:

    "In the past the national parks have done many things which people thought were good ideas at the time that turned out to be not so great ideas."

  • JES BURNS:

    In 1915, park managers introduced the Signal crayfish to feed those fish.

  • CRAIG ACKERMAN:

    "And that turned out to be a worse decision than stocking the fish in the first place, because the crayfish have become out of control."

  • JES BURNS:

    And this is obvious out in the lake.

    Scientists at the Park are finding that crayfish and Mazama newts don't really get along.

  • MARK BUKTENICA:

    "We have a stand-off. What's going to happen?"

  • JES BURNS:

    Not only do they compete for the same food, but studies done by park biologists show crayfish chase and harass the newts, causing them to flee.

    And in some cases, much worse.

  • MARK BUKTENICA:

    "They're virtually the perfect invader…….The Mazama newt on the other hand, is an ideal prey.

  • JES BURNS:

    After thousands of years evolving without predators, the newt lost it's best weapon – a potent neurotoxin that can kill.

  • MARK BUKTENICA:

    "With the loss of its toxicity, it's left virtually defenseless."

  • JES BURNS:

    But actually, crayfish in Crater Lake weren't thought to be such a problem until relatively recently.

    Surveying started in 2008, and scientists found newts had the advantage, occupying about half the the shoreline. The crayfish had most of the rest.

    By 2014, the crayfish had taken over 75 percent of the shallows.

  • JOHN UMEK:

    "I got it!"

  • JES BURNS:

    And that's not all, says biologist John Umek.

  • JOHN UMEK:

    "Crayfish are impacting all the organisms in the nearshore not only newts. For instance, in crayfish areas we don't find snails. You have to go outside the crayfish dominated areas to even find a snail or two. Instead of this great biodiversity area, it's down to one or two organisms and that's it besides crayfish."

  • JES BURNS:

    Without these tiny organisms eating the algae, the crystal blue clarity of Crater Lake could be at risk.

    Crater Lake biologist Scott Girdner suspects that climate change is playing a role. The surface temperature of the lake has increased about three degrees in the past 10-15 years.

  • SCOTT GIRDNER:

    "And it may just allow the crayfish to move faster. They're just more active at warmer waters. And it may allow them to have more successful reproduction, they're numbers have increased faster now."

  • JES BURNS:

    The team surveys the lake for crayfish each summer. They set traps all along the shore, and deep into lake.

  • MARK BUKTENICA:

    "Oh my gosh! That's a lot of crayfish."

  • JES BURNS:

    They count, weigh and measure their catch. And they tag and release some to find out how they travel.

    They've even found crayfish at 750 feet.

  • SCOTT GIRDNER:

    "Deepest known crayfish in any lake system. What are they doing at 250 meters?"

  • JES BURNS:

    Scientists expect that if crayfish continue to spread…

  • SCOTT GIRDNER:

    "It's very possible that the mazama newt would be eliminated from the lake if we didn't do anything."

  • JES BURNS:

    At this point no one knows exactly what to do. Trapping — even intensive trapping — hasn't made a dent.

    Yet there are a few glimmers of hope for the Mazama newt.

    There's the possibility of building underwater barriers or fences to slow crayfish expansion.

    Another solution could be provided by the lake itself.

    Spring-fed pools like this emerge when avalanches pile up rock berms along the shore. These pools are newt nurseries.

  • MARK BUKTENICA:

    "They'll come into these pools while there's still snow on the edges of the pool."

  • JES BURNS:

    The conservation promise is that while newts move across land to get to the isolated pools, Signal crayfish do not.

    If other strategies to stop the spread of the crayfish aren't effective, these pools could become a final stronghold for the Mazama Newt and other native animals.

  • JOHN UMEK:

    "We have the opportunity right now to potentially at least slow down the invasion of crayfish. If we miss this opportunity, I think it's going to be a lot of trouble for the newts."

  • JES BURNS:

    Without intervention, this unique creature could vanish from the lake within the next few decades.

    Controlling the Signal crayfish and protecting this unique ecosystem will be labor intensive and expensive.

  • CRAIG ACKERMAN:

    "But the park service's mission and mandate to do this above all else. So we will put the resources into this that we feel necessary."

  • JES BURNS:

    The sobering reality is crayfish will likely never be eliminated from Crater Lake.

    And maybe the best the National Park can hope to do is carve out a few safe havens for the Mazama newt.

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