Blueback trout (or Arctic charr Salvelinus alpinus) of Rangeley Lake, now extripated from this lake due to the stocking of Atlantic salmon. This illustration is from a 1915 monograph by W.C. Kendall on the fisheries of Rangeley Lakes.

Human-associated dispersals of fish species date back to pre-colonial times, but the movement of regionally-native species to watersheds and waterbodies in which they were not originally present did not become commonplace until the late 19th century. The introduction of non-native species can have drastic effects on the lake or stream system to which they are added. In the case of Rangely Lake, Atlantic salmon were stocked as a game fish, and became direct competition for the native coldwater species, Arctic charr (pictured above). Salmon were able to out-compete the charr, and as a result, Arctic charr are no longer present in the lake. Today, the problem of introduction of non-native species continues as both gamefish and baitfish are introduced illegally into lake and stream systems in Maine. As a result, Maine's native freshwater species are threatened and becoming increasingly homogenized.