Biologists with the departments of natural resources in Minnesota and Wisconsin have determined that several fish kills reported in and around the Mississippi River near La Crosse are due to hypoxia, which occurs when there are unusually low levels of dissolved oxygen. This can occur during periods of high summer temps. Affected fish in the kill were primarily bluegill, yellow perch, largemouth bass, gizzard shad, common carp and northern pike. While low oxygen levels should soon improve, it is possible that other areas of the river will be affected.