By SARAH ROY
Here in the Swan Valley, this is the resounding question. It is one of the top conservation concerns for biologists, but seems to be one of the least addressed questions in the general public.
So, why should we care about these fish? Instructor Andrea Stephens has truly been the perfect person to help students explore this question. Having spent the last 6 years in the field studying Westslope cutthroat trout, she offers a valuable insight into why these species are so special, and why they are worth saving. In order to convey this message from various perspectives, Andrea set up two full days of meetings with professionals in the field. We even made a camping trip out of it! On the first day, we toured the Creston National Fish Hatchery, and met with Wade Fredenberg of the U.S. Fish and Wildlife Service. Wade is the regional Recovery Coordinator for Bull Trout and has been working on the bull trout issue since they became listed. He informed the students about the complex (and sometimes tedious) process of dealing with a species that is listed under the Endangered Species Act. Wade also showed us some breathtaking photos of Bull Trout that were taken by National Geographic photographer, Joel Sartore:
Photos taken by Joel Sartore. (Property of USFWS)
After meeting with Wade, we headed to meet our next presenter: Clint Muhlfeld, a researcher for the U.S. Geological Survey. Clint studies aquatic ecosystems in Glacier National Park and the surrounding areas. He is currently working on a hot topic right now with westslope cutthroat trout: Hybridization. One of the biggest threats to the native cutthroat trout populations in Montana is inter-breeding with invasive (non-native) Rainbow trout. Rainbow trout have infiltrated a majority of critical habitat for westslope cutthroat trout and hybrids between these two species are actually fertile, able to reproduce with both parent species and with each other. So why is this problematic? Hasn’t hybridization always been present in biological systems? After all, it is a mechanism of creating new species. Yet this hybridization has happened in a way that is completely unnatural to the ecosystem. If it weren’t for our intentional introductions of rainbow trout, Montana’s native cutthroat populations would have never been in contact with rainbow trout. While rainbow trout are sought after as a game species, they actually pose a huge threat to the native populations of fish. And here’s why:
When the Westslope cutthroat breed with Rainbows, it causes the cutthroat’s gene pool to actually lose their local adaptations. This is a delicate thing to disturb. All species on Earth have evolved to fit into their environment, in their own unique way; when their adaptations are taken away from them (in this case via hybridization), species become less able to live successfully in their home environment. This is exactly what is happening to the westslope cutthroat trout. Because humans placed rainbow trout into an ecosystem it would not have naturally occurred in, they are causing (as Clint’s research demonstrated) a reduction in fitness of the native cutthroat trout population. In order for the students to get a closer look at this current conservation issue, we visited a site adjacent to Glacier National Park where partners from the Flathead Lake Biological Station were check fish traps for cutthroat. The students were able to view a few cutthroat-rainbow hybrids and even a bull trout.
On day two of our Flathead Valley trip, we visited with Leo Rosenthal, the Montana Fish, Wildlife and Parks area management fish biologist for the Swan and Flathead Rivers. He described the state’s plan to improve bull trout numbers by netting invasive lake trout from Swan Lake. Later we drove to the shore of Flathead Lake to talk with Barry Hansen and Evan Smith, fisheries biologists for the Confederated Salish and Kootenai Tribes. Evan took us on a tour of the tribes’ warehouse at Blue Bay where lake trout are processed for the food bank after being brought in by anglers during the popular Mack Days contest. Barry explained how Mack Days is a tool used by the state and tribes to control lake trout numbers in Flathead Lake.