History and Fluctuating Asymmetry of Utah Salmonid Broodstocks

The level of potential inbreeding in Utah salmonid broodstocks was assessed by fluctuating asymmetry (FA) of five bilateral meristic characters. Counts were made of the following characters on the left and right sides of 40 fish: gill rakers on the lower first branchial arch, gill rakers on the upper first branchial arch, mandibular pores, pectoral fin rays, and pelvic fin rays. Data from state hatchery records for the last 20 years were examined for trends in development to the eyed stage, percent hatch, and percent cripples (deformity). A brief history of Utah broodstocks is also presented. The mean FA for each of the strains of five species varied from 1.25 (Sand Creek strain rainbow trout Oncorhynchus mykiss) to 3.15 (Bonneville cutthroat trout O. clarki utah), with no consistent differences among species. The meristic counts were variable, and the overlap made differentiation among strains and species based upon these counts impossible. From 1972 to 1993, percent survival to the eyed egg stage for most Utah hatchery strains did not follow any trend, except for brook trout Salvelinus fontinalis (r = –0.712) and albino rainbow trout (r = 0.457). Eggs stripped from wild stocks of lake trout S. namaycush and kokanee (lacustrine sockeye salmon O. nerka) had significantly lower survival to the eyed stage and hatching success than eggs from hatchery broodstocks, except for brook trout and albino rainbow trout. Mean crippling rates ranged from 1.5% in kokanee to 6.6% in Strawberry Reservoir cutthroat trout O. clarki. Fluctuating-asymmetry, eye-up, hatching, and deformity data indicated either low or no inbreeding in Utah broodstocks.