Effects of Inbreeding on Rainbow Trout Populations

Abstract

Abstract An approach for measuring inbreeding depression on the basis of differences between inbred and outbred half-sib family groups is described. Using this method, estimates of inbreeding depression in populations of rainbow trout (Salmo gairdneri) following one generation of brother-sister mating was calculated for three production traits–percent egg hatchability, percent fry survival from swim-up to 150 days, and weight at 150 days. The inbreeding depression estimates obtained from male and female half-sib families were 1.7 and 4.4% for percent egg hatchability, 22.2 and 16.1% for percent fry survival, and 12.0 and 9.8% for weight at 150 days, respectively. Estimates for fry survival and weight at 150 days were significant at P < 0.01 while egg hatchability estimates were nonsignificant. Following one generation of full-sib mating, the calculated effect of inbreeding on the number of live fish and total weight of fish at 150 days of age showed a reduction of 16.1 and 24.4% in female families and 22....