Why doesn Lake Superior produce a fishery like Lake Michigan?
A. Lake Michigan is a much warmer and more productive system, which is better suited to salmon and rainbow trout that are adapted to warmer temperatures. Lake Superior is much colder and is better able to support native lake trout and lake herring as the primary predator and prey species. Lake trout and lake herring evolved in Lake Superior and are better adapted to its cold temperatures and available prey. Pacific salmon can survive in Lake Superior and have become naturalized. However, compared to Lake Michigan, their growth is slow and survival is poor. The physical environment of Lake Michigan is much more productive than Lake Superior. Lake Michigan has more in-lake shallow water habitat. Average surface temperature can be 10-15 degrees F warmer, and the optimal growing season can be 1-3 months longer, in Lake Michigan. The biological productivity of Lake Michigan is about 3 times that of Lake Superior, creating an environment better suited for growth and survival of Pacific salmo
