A variety of both native and non-native fish are found in Lake Superior. In total, there are 89 species, of which 38 are native and 21 are non-native. The lake has fewer species than other great lakes, and lower fish density. This is because it is considered ultra-oligotrophic, meaning there are relatively low levels of nutrients in the water.
Several species of perch are found in Lake Superior. The native Brook Trout, and Lake Trout are found, as are the non-native Brown Trout and Rainbow Trout. The Brook Trout, the only stream-dwelling trout native to the Great Lakes, is around 10 to 16 inches long, and is green and brown. The Lake Trout is 17 to 27 inches and light colored. Few survive in the lake, but scientists are working to increase stocks. The Brown Trout is 16 to 24 inches long, green/brown in color, and originally from Europe. The migratory Rainbow Trout is 20 to 30 inches long, and silvery.
The main species of perch in the lake are the native Yellow Perch and the non-native White Perch. The Yellow Perch is 6 to 10 inches long and green-brown. It is adaptable and lives in a range of habitats in the lake. The White Perch was introduced to the Great Lakes in the 1950s via the Erie and Welland Canals. It is native to the Atlantic coast. It is 5 to 7 inches long and grayish-green or brown.
The main species of salmon found are the Chinook Salmon, Coho Salmon and Pink Salmon. All are non-native. The Chinook Salmon is large, up to around 50 inches long. They are known as King Salmon, and are a common trophy fish for fishermen. The Coho Salmon is 11 to 26 inches and silvery, and popular with sport fishermen. The Pink Salmon is 14 to 18 inches, blue/green and silver, and often caught commercially. The Atlantic Salmon is also sometimes found but does not reproduce in the lake.
Sturgeon measure around 3 to 5 feet long, and are known to many as 'living fossils'. They are brown and gray, and covered in bony plates. They tend to move slowly along the bottom of the lake. They are prized commercially, especially for their caviar. They live for 50 years, but only spawn every four to six years, making them vulnerable to overfishing.