I read a great article titled ‘Too Warm For Trout?’ a couple of weeks ago by Kim Barto in Compass - a publication by the US Forest Service’s southern research station. I’ll do my best to summarize the article in a short paragraph or two.

Trout fishing is a deeply entrenched tradition of the southern Appalachian Mountains. The globe’s current warming trend (notice I did NOT say global warming - that term is way too politically ‘loaded’ to be meaningful anymore) poses a threat to trout populations if it continues, especially in lower elevation rivers and streams throughout the Southeast. Being a coldwater species, trout depend on low stream temperatures to survive. Given the slight temperature increases of past decades and the fact that trout are already at the southern limits of their range, trouble might be brewing in the future. Add in the fact that woolly adelgids are hammering the mountain’s hemlock tree populations (a dominant canopy species along many mountain streams that provides shade and cooler water temperatures), stream temperatures are also the rise. Using 2 different models, researchers found that 53% (conservative model) - 97% (extreme model) of trout habitat could be lost to land cover disturbances, sedimentation, road building, and most importantly water temperature increases.

Now, the likelihood that trout will suffer a 97% decline is certainly not likely, but the research does reveal an inevitable trend that has happened some already and will surely pick up speed if average temperatures increase. Warm weather species that used to be restricted by cold temperatures along their northern range boundaries will extend their distribution to the north, and the southern boundaries of cold temperature species will simultaneously be driven farther north.

The researchers made it clear that small populations of trout in low elevation streams surrounded by dying hemlock trees will be at the highest risk of local extinction.