Centennial fish stocking at Mount Rainier now studied with DNA to protect native wildlife

Between 1915 and 1972, Mount Rainier National Park introduced more than nine million fish into its naturally fishless streams and lakes to support sport fishing, fundamentally altering aquatic ecosystems. Today, about 35 lakes still sustain breeding populations of non-native fish, which prey on amphibians and compete with the federally threatened bull trout. Scientists are now using environmental DNA (eDNA) techniques to efficiently detect species presence by filtering water samples, complemented by traditional capture methods and fin-clip genetics to distinguish stocked from native lineages.

The joint research program, involving the National Park Service, USGS, the Puyallup Tribe of Indians and the U.S. Fish and Wildlife Service, has collected dozens of eDNA samples and hundreds of char genetic specimens across watersheds such as White, Puyallup, Mowich, Carbon, Huckleberry Creek, Ohanapecosh and Nisqually. Their goals are to map aquatic species distributions, assess genetic diversity, and confirm whether Dolly Varden inhabits the park, information that could shape future fishing regulations and amphibian habitat protection.