Another important value of nongame fish is their link in complex ecological chains. For example, the disappearance of the ebony shell mussel in the upper Mississippi River has been traced to the disappearance of the skipjack herring, which assists in ebony shell distribution by transporting the mussel's larvae in its gills. In Ohio, the gizzard shad has been closely linked to bluegill reproduction and walleye growth in large reservoirs. What's more, birds such as loons, herons, and kingfishers depend on dace and shiners for food. Otters and other water-based predators feed on these smaller fish species.
Nongame fish can also belong to a group of animals known as keystone species.
These seemingly insignificant animals act like the keystone at the top of an arch, holding the entire ecological structure together. According to John Lyons, a fisheries research biologist with the Wisconsin DNR, the hornyhead chub and stoneroller are considered keystone species for Upper Midwest streams. These fish, when digging out their nests, make gravel piles used for spawning by red-bellied dace, rosyface shiners, and other stream residents. Without the hornyhead chub and stoneroller, entire stream food chains could break down. Some studies being done As is the case in most states, Minnesota has yet to formally embrace nongame fish management.