YELLOWSTONE — On Thursday, May 2, Yellowstone National Park announced updates to its Native Fish Conservation Program, a plan which works to reverse the decline of native fish populations in Yellowstone and restore ecosystem integrity.
During the Native Fish Conservation Program Update event, which took place earlier this week, Leader of Yellowstone’s Native Fish Conservation Program Todd Koel and Yellowstone Aquatic Invasive Species Biologist Mike Canetta discussed lake trout control and cutthroat trout recovery in Yellowstone Lake, native fish restoration in park streams, 2024 angling regulations and aquatic invasive species prevention.
Koel shared some of the history of nonnative fish species being introduced into the park in a short on-location video presentation.
“Yellowstone National Park sits along the continental divide, and is the headwaters of Yellowstone River, Madison River, Gallatin River and the Snake River, and these are really pristine aquatic environments within which are native fish that have been able to persist for thousands and thousands of years,” Koel said in the video. “When the park was first created in 1872, there were 12 native species…and the most known are the cutthroat trout, white fish and arctic grayling, which are native sport fishes of Yellowstone.”
Koel explains in the video that approximately 12,000 years ago, the receding of glaciers created a barrier for fish to access approximately 50% of the waters in the park. In 1889, when people started to settle in the region, they took it upon themselves to stock the park’s waters with nonnative fish. For decades, fish from outside of Yellowstone were moved into the park to colonize these historically fish-less waters. At the time, it was not recognized what the impact of non-native fish species would be on native fish communities and natural ecosystems. By the 1930s it was understood that nonnative fish such as brook trout, brown trout and rainbow trout began displacing the native cutthroat trout.
According to YNP, the stocking of nonnative species ended in the mid-1930s but by that time, irreversible harm had already been done to native fish species.
In 2010, the National Park Service (NPS) implemented the Native Fish Conservation Plan, to address threats to Yellowstone’s native fisheries. Updates to the plan include targeted actions in native fish recovery, public education and ecosystem monitoring. Plan updates also focus on the conservation of native fish species from threats of nonnative species, disease and the impacts of climate change.
In Yellowstone Lake, gillnet operations are utilized to control fisheries, and to collect data, including lake trout population, age, maturity and potential spawning areas. A gillnet is a wall of netting that hangs in the water, typically made of multifilament nylon. The net is designed to allow fish to fit their head through the netting but not their body. Since 1994, over 4.5 million lake trout have been removed from Yellowstone Lake with gillnets.
In other Yellowstone lakes, rivers and streams, headwater refuges are created. Natural waterfalls are enhanced or artificial barriers are constructed to block nonnative fish from moving upstream. Fish toxins (piscicides), like rotenone, are often used to control nonnative fish. Rotenone is toxic to gill-breathing organisms but relatively safe for humans and wildlife. Remote site incubators and live fish stocking are the two methods used for native fish reintroduction.
Since 2007, over 200,000 westslope cutthroat trout and 400,000 Arctic grayling have been introduced to 67.2 stream miles and 281 lake acres in the Gallatin and Madison watersheds, according to YNP.
YNP says that assistance from visiting anglers is also a critical part of the conservation effort. Anglers can remove nonnative fish, but all native fish must be released unharmed, including cutthroat trout, mountain whitefish and Arctic grayling.
“If the Yellowstone cutthroat trout were to disappear, and we were to allow the lake trout to thrive within the lake, many of the animals that depend on the cutthroat trout would also be displaced or gone,” Koel said on Yellowstone’s website.
The recording of the Native Fish Conservation Program Update is now available to the public, and is located at the bottom of the page, in the question and answer section.
