USDA - ARS

Trout-Grains Project

Improved Trout for Plant Feeds

For four generations two year classes of rainbow trout have been selected for growth when fed a diet that contains no fish meal and only protein from plant sources. Because trout take two years to reach sexual maturity we maintain two year classes of selected broodstock.

This stock was developed by introgressing eight different stocks of rainbow trout from the following sources: Housecreek and Oregon strains from the College of Southern Idaho; Arlee, Shasta, and Fish Lake from National Fish Hatchery in Ennis; Kamloop and R9 strains from the Idaho Fish and Game Hatchery in Hayspur, Idaho; and the Donaldson strain from the University of Washington in Seattle Washington.

Over 100 individual family crosses are annually generated and then evaluated for growth and feed conversion when fed plant-based diets. The top 10% of the fish from the best performing families are tagged and used as broodstock in future years. Current generations show significant increases in growth compared to domesticated control fish, when fed plant-based diets.

During the selection process we have also increased the number of eggs per spawn and survival rates of the selected fish. The improved fish have also been extensively characterized for a number of growth indices and for the expression of several genes associated with growth, protein turnover, immune function and nutrient regulation.

Families from this program have been incorporated into commercial broodstock programs and are contributing significantly in commercial production. These fish are currently available for limited release to commercial producers with broodstock programs.