Transboundary Flathead Fisheries Baseline Data Collection

Deleray, Mark; Cavigli, Jon; Steed, Amber; Selch, Trevor

In May 2008, the National Park Service, Glacier National Park (GNP), and Montana Fish Wildlife and Parks (FWP) entered into a cooperative agreement for the purpose of supporting fisheries investigations in the Transboundary Flathead River drainage prior to implementation of proposed mining and other development activities in British Columbia, Canada (BC). The work plan consisted of three separate projects. The first investigated baseline contaminant levels in fish tissues in the Transboundary Flathead River and Elk River drainages. The second determined baseline fish species distribution and genetic status of westslope cutthroat trout in the Transboundary Flathead River and GNP. The third implemented a monitoring strategy for fisheries resources in BC and GNP. The agreement received one year of proposed three year funding resulting in partial completion of the proposal. The monitoring strategy was not developed. Results from the contaminant level investigation showed differences in selenium (Se) concentrations in fish tissues from different water bodies. Westslope cutthroat trout from Flathead Lake had the lowest mean Se concentrations in both muscle and liver tissues while those from the Elk River showed the highest concentrations. Sites near the proposed Cline Mine in the upper Flathead River and Wigwam River drainages (Flathead River, Lodgepole Creek, and Foisey Creek) showed intermediate concentrations, all lower than the Elk River sample. The Elk Valley Selenium Task Force largely comprised of representatives from private coal mining companies and the BC government found elevated selenium levels in water, sediment and biota downstream of coal mines that were directly attributed to coal mining activities. This included elevated selenium concentrations in fish tissues. Coal mining in the Flathead River Drainage would likely result in elevated selenium concentrations in downstream fish populations, including migratory fish species. We found bull trout in all Flathead River tributaries sampled to date as part of the tissue analysis survey. Migratory fish species are widely distributed throughout the Flathead River drainage in BC. The headwaters of the Transboundary Flathead River and its tributaries as well as tributaries within GNP were surveyed for fish species distribution, habitat characteristics, and genetic structure during 2008. Westslope cutthroat trout and sculpin were found throughout much of the upper system, including near proposed mining locations. Bull trout were also found in close proximity to potential mining sites. Genetic analyses of westslope cutthroat trout indicated no introgression with rainbow trout in the headwaters of the drainage. Length frequency histograms of westslope cutthroat trout indicate a likely resident component with a potential migratory form present. Too few bull trout were detected in a given patch to construct very informative length frequencies, though fish present likely represent rearing fluvial and/or adfluvial juveniles. Habitat parameters characterized include gradient, reach length, average stream width, presence of large woody debris, temperature, elevation, and substrate dominance. The third part of the proposal implemented a fisheries monitoring strategy for the BC portion of the Flathead River Drainage. This was not implemented due to funding limitations; however, FWP completed bull trout redd counts as part of basin-wide surveys intermittently conducted since 1980, every three to five years. FWP also annually surveyed the river near the proposed mine site since 2006.