Performance and fertility of triploid Atlantic salmon and Atlantic salmon x brown trout hybrids

Experiments were conducted to assess the performance characteristics and sterility of triploid all-female Atlantic salmon and Atlantic salmon x brown trout hybrids. One series of experiments involved comparisons of viability to initiation of feeding, and of survival and growth in fresh and saltwater of mixed-sex diploid and triploid Atlantic salmon and Atlantic salmon x brown trout hybrids. Viability of the diploid hybrid to initiation of feeding was equal to that of diploid Atlantic salmon, and triploidization in both crosses caused comparable decreases in survival. Survival in freshwater and saltwater was similar and high in all crosses. Growth of triploid hybrids was slower than, similar to, or faster than that of diploid and triploid Atlantic salmon, depending on the trial.; Diploid and triploid Atlantic salmon x brown trout hybrids were raised to maturity and backcrossed to both parental species to assess the potential for introgression via hybridization. Progeny of backcrosses with male diploid and triploid hybrids all died prior to or shortly following initiation of feeding. Viable progeny were obtained from backcrosses with female diploid hybrids, but these fish were all triploid, and therefore sterile.; A second series of experiments compared survival and growth of diploid and triploid all-female Atlantic salmon in fresh and saltwater. Early freshwater growth in separate rearing tanks was significantly faster for triploids, but was slower during subsequent communal rearing to the age of smoltification. Mortality of triploids was greater than that of diploids following transfer to saltwater. Growth of triploids during communal rearing in a saltwater net-pen was similar to or slightly less than that of diploids.; The performance characteristics and sterility of triploid all-female Atlantic salmon and triploid Atlantic salmon x brown trout hybrids make them of interest as alternatives to diploid Atlantic salmon for use in commercial saltwater net-pen culture. Commercial scale studies are recommended to more completely assess this potential.