Stocking Density, Strain Performance, and Feeding Method Evaluation of Cage Reared Rainbow Trout (Salmo gairdneri) in Eastern South Dakota

Methods for cage rearing rainbow trout (Salmo gairdneri) were investigated to assist in the development of a landowner aquaculture program for eastern South Dakota. Rainbow trout when stocked as small fingerlings in the spring did not reach a marketable weight (200 g). The fish did attain a size acceptable to some landowners for personal consumption. Maximum stocking density (fish/m3) was not determined. Densities greater than those used would have been needed to determine the optimum stocking rate. The use of a deeper culture cage (3 m) was justified in this area due to the high water temperatures that were common. Growth and survival of three strains of cage reared rainbow trout were compared in a gravel pit environment. The Hildebrand strain performed significantly better (p\u3c0.01) than the Kamloops and Growth strains for the variables length, weight, survival, and relative weight. An automatic fish feeder and a demand feeder were developed for use in remote locations with cage culture. The automatic feeder treatment produced larger fish than either the demand feeder or hand feeding treatments. Cage culture of rainbow trout in eastern South Dakota is presently not economical in the type of water bodies investigated due to a short growing season imposed by high lethal water temperatures in late June or early July