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The Battle to Save Yellowstone from Invasive Fish [Slide Show]

The National Park Service is scoring some victories in its fight to eradicate nonnative lake trout from Yellowstone’s largest lake

By Ben Goldfarb

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LAKE INVADERS:

Released by an anonymous angler in the 1980's lake trout have come to dominate Yellowstone Lake—sending native cutthroat trout into steep decline and wreaking havoc on this iconic ecosystem. Now, the National Park Service (NPS) believes its intensive gillnetting efforts are turning the tide against the invader.....[ More ]

GONE FISHIN’:

Cody Bex research captain for Hickey Brothers Fisheries, a commercial fishing company hired by the NPS, pilots the Freedom into Yellowstone Lake’s south arm. When Bex and his crew fished this site earlier in the spring, they netted nearly 1,800 lake trout in a day.....[ More ]

NET GAINS:

As Tom Petty and the Beatles blare over the ship's stereo, Hickey Brothers fishermen extract small lake trout from a 2,745-meter-long gillnet. "A few years ago they used to spend all day picking one gang of nets because there were so many fish," says Bex.....[ More ]

REELING ‘EM IN:

These nets had been submerged for four days at around 50 meters. In the fall, when lake trout move closer to shore to spawn, the gillnet boats will turn their attention to the shallows.....[ More ]

CATCH AND RELEASE:

NPS biologist Phil Doepke releases a native cutthroat trout—displaying the distinctive red slash mark that gives the fish its name—that had become entangled in a gillnet. Cutthroat tend to inhabit shallow waters whereas lake trout prefer depths below 50 meters, allowing crews to selectively target the invaders by setting nets deep.....[ More ]

SMALL FRY: 

A few of the 421 lake trout caught by the Hickey Brothers boat in a single net. Smaller lake trout, like these 20-to-28-centimeter-long specimens, remain abundant but large lakers are increasingly scarce.....[ More ]

CATCH OF THE DAY:

An eight-kilogram lake trout emerges from Yellowstone Lake, trapped in an NPS gillnet. According to one study, the average lake trout eats 41 cutthroat each year; this one had three in its belly.....[ More ]

SPAWNING SECRETS:

Justin Walley, an intern with the Student Conservation Association, holds up the eight-kilo specimen. Back at the NPS’ Fisheries and Aquatic Sciences laboratory, scientists with the U.S. Geological Survey find this fish contains 12 ounces of roe, eggs it would have released this fall.....[ More ]

CALF CONSEQUENCES:

​An elk grazes in the floodplain of the Yellowstone River. As cutthroat have declined, grizzly bears’ spring diets have shifted from fish to elk calves, a change that could reduce the growth rates of Yellowstone's migratory herds.....[ More ]

HYBRID WATCH:

Lake trout aren’t the only nonnative fish affecting cutthroat trout populations. Here, an NPS fisheries technician examines a cutthroat for signs of hybridization with rainbow trout, a Pacific coast native introduced to Yellowstone by park administrators in 1889.....[ More ]

CUTBOW CRISIS:

The view from Cache Creek, a tributary within the Yellowstone River watershed in which cutthroat trout are threatened by hybridization. Recent research suggests that cutthroat–rainbow hybrids, called cutbows, are not as fecund as genetically pure fish—and that hybridization could increase as climate change allows rainbows to move higher up mountain streams.....[ More ]

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