By JULIA GOODHART
After our venture into the Bob Marshall, we plunged headlong into the first few days of our Watershed Dynamics and Management course!
We began by exploring the stretch of the Swan River we pass whenever we travel to and from the barn. It was really interesting to begin to understand the river features we see so often!
We walked to the edge of the extensive floodplain, and found the ancient river terraces coursing through our own pastures – remnants of the river’s shifting path over thousands of years. Like the glaciers, we can trace the historical journey of the river based on all it has left behind.
To put their knowledge to the test, students were asked to carve within the sand a river system that included specific physical features.
In the photo above, Sophie describes the cut banks and point bars, mid-channel bar, lateral scour pools, eddies, riffles and pools they included in their diagram.
We investigate human-constructed features on the river too! Above, students gaze into the pool below Cold Creek Bridge. The bridge confines the river’s movement at this point, which causes the force of the water to carve down into the river bed rather than away at either bank where the bridge is significantly reinforced.
We continued with river features, exploring Elk Creek’s riffles and pools until we reached Elk’s confluence with the Swan River. We focused on the importance of these gravel-bed rivers to fauna in the valley. This includes creatures like invertebrates and young-of-the-year sculpin living between the gravels, as well as the ungulates and carnivores that rely on the floodplain for plant forage or grounds for hunting.
We were fortunate to come upon some beautiful mountain lion tracks! On the same muddy shore, we found evidence of grizzly bear and a group of coyotes – all evidence of the critical habitat that a meandering river and its extensive floodplain provides.
On to snorkeling! The students spent several hours snorkeling the Swan River, in part to document the individual fish they were able to see, but also to better understand habitat structure. What constitutes great fish habitat? Where are most of the fish found when snorkeling? What happens under water when one tree falls into the stream?
Though we didn’t see as many fish as we were expecting, we saw many sculpin, groups of juvenile mountain whitefish, and a handful of rainbow and brook trout. You can tell how awesome the afternoon was from Evan’s pose in the photo above.
To finish out our first few introductory days, we went electrofishing! Swan Valley Connections has been working for 6 years throughout the Swan watershed to understand the distribution, abundance, and genetic purity of our native westslope cutthroat trout. The students helped us to finish out our last site on Dog Creek on the Swan Front.
Andrea can be seen in the photo above with the backpack electroshocker, directing students before moving into the pool. The electric current stuns fish for a few seconds, so there is only a brief window where they are easy to net! We tried to block any escape routes, and had several people behind the initial netters to catch any fish that may have slipped through.
We carried our fish along with us in a bucket of fresh water until the end of the reach, where we documented the species and length of each fish. For the one- and two-year-old westslope cutthroat, we took a tiny snip of tissue from the caudal fin. This small fin clip will be sent to the University of Montana Conservation Genomics lab to help determine if the fish are genetically pure, or if they have been hybridizing with rainbow trout. These samples will be compared with those from 4 years ago to also understand if levels of hybridization are increasing. The fish are returned to the stream after this minor processing.
The genetic samples we collected on Dog Creek will be combined with all the others the SVC field staff gathered over the course of this field season, as well as samples collected by our partners at the Forest Service, Montana Fish, Wildlife and Parks, the University of Montana and the US Geological Survey. All together these tiny bits of hard-won data will help paint the picture of the status of the Swan’s remaining westslope cutthroats.
By identifying our genetically pure cutthroat trout populations, which have been reduced to less than a fifth of their historic range, we can better direct our management resources and help protect those remaining populations. Since the hybrid fish are actually less able to survive in the cold, rocky, high-elevation tributaries where cutthroat thrive, we may lose important biodiversity if the populations hybridize until westslope cutthroat disappear.
It was an important learning experience for all, and an awesome look at what “field work” can look like. We can’t wait to learn more about our watersheds and the policies that govern them during our upcoming trip to the Mission Valley!