Lakewide fish population surveys are conducted each year to monitor trends and dynamics of prey fishes used by top predators such as salmon and trout. The lake herring suvey is described below.

Lake herring was the principal forage fish of Lake Superior but declined from over fishing in the late 1950s and early 1960s. Only in the last 10 years has their population rebounded through the establishment of strong year-classes.

Data generated from these surveys, increases our understanding of how fish populations fluctuate and the causes of these fluctuations. The data is also being used to estimate the number of predators that can be supported by these prey populations and that will have impact on how many salmon and trout should be stocked by management agencies.