a threat to this species since they inhabit a wide range of temperature gradient throughout the United States. However, one human activity that affects them is runoff from mining, which particularly is harmful to the newly hatched larvae and developing eggs. Nothing is being done for current management for the mottled sculpin because it is a very abundant fish where it occurs. Future management could focus on the different metals that leak into the water from mining. The absence of the mottled sculpin from an area could tell us that the area has high levels of zinc, cadmium, or copper. Geographic distribution of species The mottled sculpin, Cottus bairdii, is known to inhabit a large geographical range in North America. Their natural habitat range is from Northern Canada down to the Mobile and Tennessee River drainage systems. They are also commonly found in streams in the Rocky Mountains along with many streams found throughout the Midwest United States. The mottled sculpin has historically been found throughout all the environments listed above. For the most part, the geographical range of the mottled sculpin has not changed throughout the years due to it is being a resilient fish and because it has a large temperature gradient in which it can reside. However, in a study by Besser and others in 2007, mottled sculpins have been absent in streams thought to be populated by them in the past due to the species being more sensitive to toxic levels of cadmium, copper, and zinc than species of salmonids. Of these three metals zinc seems to be the most threatening to the mottled sculpin. One study found mottled sculpins to be the third most sensitive aquatic species to zinc. Therefore, the biggest threat to the species would be high mining areas or areas where coal is burned frequently. Ecology Mottled sculpins are known for living in fast moving current areas where they feed primarily on bottom dwelling aquatic insects. One study found that bottom dwelling aquatic insects make up 99.7% of the mottled sculpin's diet, with dipterous larvae and pupae being the most common type found. The remaining 0.3% was made up of snails, fingernail clams, water mites, sculpin eggs and fish. Thus the mottled sculpin is not a major threat to game fish though it has been found to eat trout eggs.<ref name=Dineen>Dineen, C. F. 1951. A comparative study of the food habitats of