Ciscoe, a prey species of gamefish such as lake trout, are experiencing die offs more frequently in recent years. This is likely to be caused by raised water lake temperatures and run off from surrounding areas that depletes the water of oxygen. Populations are significantly declining in some lakes. 

Some studies have predicted that the climate of Minnesota will become equivalent to Kansas in 85 years. For coldwater fish such as Ciscoe this is bad news since this would increase the die offs even more. 

For more on this story goto the StarTribune. Its very interesting reading the comments. Some good examples of ignorance about global warming.