These small trout are an ideal disease free forage for the host fish of the endangered Higgins eye Pearlymussel. The remaining fish are reared to a catchable size of 11 inches and released for recreational fishing. - USFWS photo

The Genoa National Fish Hatchery (NFH) received 330,000 rainbow trout eggs on Jan. 31, 2006 from the Ennis NFH. The majority of the resulting fry will be reared to two inches in length by April 2006. They will then be used as forage to feed approximately 12,500 largemouth bass and walleyes which will be used as host fish for the endangered Higgins eye pearlymussel.

These 5” to 6” host fish have been held in an icy one-acre pond throughout the winter at the Genoa NFH. In early April, these fish are harvested from the pond and are placed in rearing tanks until the time is right to artificially inoculate larval mussels on their gills for restoration and recovery efforts within the upper Mississippi river basin. By the end of the cold winter, these host fish are in excellent condition, however as temperatures rise, so does their hunger.

One problem that biologists face is the possibility of compromising the health of the host fish if the fish are fed a forage species of fish which may harbor fish diseases and parasites. Fortunately, this chance can be eliminated by feeding a rainbow trout to the bass and walleye. This is possible due to the fact that the rainbow trout eggs are received from the Ennis NFH which has a disease free classification, and that rating is maintained throughout the rearing process at the Genoa NFH. Thus, the rainbow trout forage ensures healthy and well fed fish throughout the mussel propagation season. The remaining 25,000 rainbow trout, that are leftover from the feeding program, are grown to a size of 11 inches over 12 months for recreational fishing programs on tribal lands and federal military bases.