![]() ![]() Instead, nonnative trout use improved stream habitat to expand their own populations. Further, these nonnative trout can reduce or eradicate native brook trout by excluding them from any new prime habitat created by stream enhancement projects. This is because nonnative trout have been shown to exclude brook trout from those thermal refuges and other prime habitats, as demonstrated in multiple studies. This is why there is no such thing as conservation of an invasive species. Invasive species decrease biodiversity and destabilize ecosystems. “Conservation” aims to maintain biodiversity because ecosystems that have more different species are less susceptible to instability. Wild native brook trout, on the other hand, are listed as a species of greatest conservation need in the 2015-2025 Pennsylvania Wildlife Action Plan. Brown and rainbow trout are listed by the International Union for Conservation of Nature on their top 100 world’s worst invasive species list due to harming many native species around the world. It’s time we face the threat that nonnative trout pose to wild native brook trout in Pennsylvania. Per EBTJV, “Regional experts cited competition and predation from brown trout as the third highest ranked impact across the state.” ![]() However, they rate nonnative trout introductions as the third biggest issue-ahead of urbanization and sedimentation. According to the EBTJV, those are the top two issues. If you guessed that poor land use practices and warming water were to blame, you would be only partly right. A 2006 Eastern Brook Trout Joint Venture (EBTJV) report stated that Pennsylvania had fewer than 1% of historically wild native brook trout sub watersheds “intact” (>90% occupied). Pennsylvania isn’t doing enough to save its remaining native brook trout. This article was originally titled "Pennsylvania Natives" in the "The Migration" column of the April-May 2023 issue. ![]()
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