The Great Lakes are 1.6 degrees Celsius warmer than they were in the 1940s, according to daily temperature readings from the City of Belleville’s pumping station that draws water from the Bay of Quinte.
For fish, that’s a significant change that affects all aspects of their physiology, from spawning rates to growth to feeding patterns. Casselman’s research shows rising temperatures have caused a two-and-a-half fold decrease in the population of cold water fish such as northern pike or trout, while fueling a population boom for warm water fish such as bass.
https://thenarwhal.ca/out-in-the-great-lakes-an-alarm-is-sounding/