Glacier National Park Fisheries Inventory and Monitoring Report, 2010--2012

Downs, Chris; Woody, M; McKeon, B

Summary report of program activities, 2010-2012. Aquatic Invasive Species (AIS) efforts are summarized in addition to fisheries inventory and monitoring. In 2009, Glacier National Park began development of a monitoring program for native salmonids inhabiting park streams. The intent of the program is to establish baseline abundance levels in key streams that will serve as useful benchmarks for monitoring changes in populations over time. We continued this work in 2010-2012, conducting sampling in 13 streams. Wild Creek (St. Mary drainage) had the highest density of age-1 and older west slope cutthroat trout (wct) Oncorhynchus clarkii lewisi, estimated at 24.4 fish/100m2 in 2012. This is an unusually high estimate and was driven by a very strong age-1 year class. The next highest density estimate for 2010-2012 for wct in any streams was in Muir Creek (Middle Fork Flathead drainage) in 2010 (13.6 fish/100m2). Boulder Creek (St. Mary River drainage) had the highest density of age-1 and older bull trout, estimated at 6.6/100m2. Many sites also supported tailed frogs Ascaphus truei and spotted frogs Rana pretiosa. Some culverts along the Camas Road may be important isolating mechanisms protecting genetically pure wct from downstream rainbow trout introgression. Similarly, Autumn Creek (tributary to Bear Creek) is protected by a large culvert under the railroad line. Management and conservation of native fish in the North and Middle forks Flathead River remains complicated due to the presence of migratory and resident populations of native salmonids, and expanding distribution of non-native fish species. Until recently, Midvale Creek supported the only known remaining genetically pure wct population in the Upper Missouri River drainage in the park. Recent genetic data show the population was recently compromised by rainbow trout and suppression actions were conducted in 2010 and 2011. Wild Creek (St. Mary tributary) supports one of the only remaining genetically pure wct populations on the east side of the park, yet maintains seasonal connectivity to the mainstem river. Evaluation of seasonal connectivity of Wild Creek to the St. Mary would provide valuable information when considering management and conservation needs of this population. In general, the largest threat currently facing migratory native fish species on the east side of the park is the unscreened St. Mary water diversion, part of the Milk River Irrigation Project.

Glacier National Park Fisheries Inventory and Monitoring Report, 2010--2012

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