Troubled Waters - Transcript
On the surface, Yellowstone’s waters look peaceful and pristine. But look closer, and things aren’t what they seem. There’s trouble in Yellowstone’s waters.
Aquatic invaders – including fish, snails and parasites – are waging an assault on Yellowstone’s native inhabitants. Invasive species frequently out compete native plants and animals for food and living space. Often they have few predators in their new home.
Name: Lake Trout
Origin: Great Lakes
Wanted for: Eating native trout
Having hitchhiked their way into Yellowstone with the help of humans, these invaders are thriving.
Name: Whirling Disease Parasite
Wanted for: Infecting native trout
The impacts of these unwelcome invaders ripple across the ecosystem, affecting all living things.
Name: New Zealand Mud Snail
Origin: New Zealand
Wanted for: Out competing natives
So biologists have launched a counterassault to try to stop them from taking over.
[Phil Doepke, fisheries biologist:] “I’ve been working on the gillnetting program on Yellowstone Lake where we’re trying to remove exotic lake trout from Yellowstone Lake.”
Name: Phil Doepke
Specialty: Lake Trout
[Phil Doepke, fisheries biologist:] “Lake trout found their way into Yellowstone Lake most likely through anglers bringing them from Lewis Lake to Yellowstone Lake.
“In other lakes where lake trout have been introduced where cutthroat trout were present, the cutthroat trout population has decreased by 90%. So it is very likely that would occur in Yellowstone Lake where the cutthroat trout population would be decimated by lake trout.
“Lake trout are not a very good replacement for cutthroat trout because Yellowstone cutthroat trout live in a different habitat than the lake trout. Yellowstone cutthroat trout live in the shallow waters of the lake and ascend streams to spawn where the lake trout live in deep waters of the lake and do not ascend streams to spawn. So they’re not available to predation like the cutthroat trout.
“Forty-two species of vertebrates use nutrients from cutthroat trout, such as bears, eagles, ospreys, otters.
“The last two years, we’ve removed over 30,000 lake trout from the lake each year. And including this year – it’s likely we’ll get to 40,000 this year.”
[Julie Alexander, whirling disease researcher:] “Invasive species have been a problem for a long, long time - ever since humans started moving at all. Generally, they fill a niche that no one else can compete with. There’s just nothing the native species can do. They don’t stand a chance.”
Name: Julie Alexander
Origin: Ottawa, Canada
Specialty: Whirling disease
[Julie Alexander, whirling disease researcher:] “Whirling disease is caused by an introduced parasite, actually, that we believe came from Europe. The parasite gets into the trout in the water column of the stream, it moves through the trout’s nervous system into the brain stem where it causes inflammation and puts pressure on the brain. It tends to make the fish whirl, it causes black tail. And basically they tend to die if infected young enough.
“The Yellowstone cutthroat trout, which are a high priority for conservation, are the most highly affected and highly susceptible. There really isn’t anything out there just yet to treat wild fish for whirling disease. Basically, the best available treatment option we’ve got now is to prevent spread of the parasite, prevent its introduction.”
[Jeff Arnold, fisheries biologist:] “New Zealand mud snails first showed up in the park in the mid 1990s and it’s believed that they hitched a ride on fishermen’s gear, gear that was not properly cleaned before they came to the park, and they were introduced that way.”
Name: Jeff Arnold
Specialty: New Zealand Mud Snails
[Jeff Arnold, aquatic ecologist:] “The bad thing about New Zealand mud snails is that they can reproduce asexually, meaning that they don’t need male and female snails to have babies. And it only takes one mud snail to be introduced into the park waters to produce thousands and thousands of mud snails in succeeding generations.
“Aquatic nuisance species in the park – which are basically non-native species - can drastically affect the economy – the local economies – because they can out compete native fishes, they can reduce the native fish populations like Yellowstone cutthroat trout, westslope cutthroat trout, and, as a result, fisherman may not come to the park and it can really affect the economy of the area.”
Despite our best efforts, it is unlikely that these invasive species will ever be completely eradicated from Yellowstone. If native species will survive the flood of invaders, they will need the help of another relatively new arrival: us.
[Julie Alexander, whirling disease researcher:] “We as humans and visitors to the park – especially in Yellowstone National Park which as we know is our first national park. It seems like a pretty important place to conserve the native species. We do have a responsibility to preserve what was here, at least to the best of our ability.”
[Phil Doepke, aquatic ecologist:] “This is kind of the center of the Yellowstone cutthroat trout’s range, and it’s kind of their last stronghold. So it would be shame to remove that population or reduce it any more than it has been.”
[Julie Alexander, whirling disease researcher:] “Basically, just be really careful when you’re fishing. Don’t move live fish in between areas, clean your waders with a 10-50% bleach solution, clean your fishing gear.”
[Jeff Arnold, aquatic ecologist:] “Everybody is responsible for keeping the park in the most pristine condition as possible.”