Relative Return to Creel of Triploid and Diploid Rainbow Trout Stocked in Eighteen Idaho Streams

Abstract Introductions of fertile nonnative hatchery trout have led to interspecific and intraspecific hybridization of native salmonid stocks throughout North America. Use of sterile triploid hatchery trout in stream-stocking programs could reduce genetic risks to native stocks while addressing public demand for consumptive fishing opportunity. Techniques to produce triploid salmonids are well developed, and triploid rainbow trout Oncorhynchus mykiss are readily available from commercial sources. However, there is no published information on the return to creel of triploid trout in stream recreational fisheries. We purchased mixed-sex triploid and diploid rainbow trout eggs from a commercial supplier and reared the resulting fish to catchable size. Flow cytometry was used to verify triploid induction rates in the triploid group. Estimated cost to produce a triploid catchable rainbow trout was about 15% higher than for a diploid fish. We jaw-tagged and stocked 300 triploid and 300 diploid fish into each o...