The heat wave is taking its toll on fish in the Upper Midwest. High water temperatures and low oxygen levels have combined to kill thousands of fish in Minnesota, the Dakotas and Wisconsin.
Thousands of northern pike died in several shallow southern Minnesota lakes since last week. Large numbers of northerns have also died in shallow southern Wisconsin lakes, as well as in the James River in southeast North Dakota and northeast South Dakota this past week.
Northerns are vulnerable because they're better suited to cooler temperatures and can't seek refuge in the depths when lakes and streams are less than 6 to 8 feet deep.
While the region's most popular fishing lakes have been spared, officials warn that additional die-offs are possible as the summer progresses.