Thanks to Mike Jones for sending me the link to this journal entry which suggests that it is herbicide usage that has been killing the fish, ery disturbing if this is the case…
“According to a permit filed with Department of Natural Resources, Lake Restoration of Rogers was contracted by 33 lakeshore owners to treat the areas in front of their properties with chemicals to kill curlyleaf pondweed and algae. Under the permit, about 5 acres of the 700-acre lake were treated”