Success of two methods for long distance transport and fertilization of Bull Trout

ABSTRACT Objective The use of captive breeding programs for the conservation of freshwater fishes, be it for research or reintroduction, is becoming more common. Interspecific differences in rearing ecology make applying common rearing techniques difficult for threatened species. This becomes increasingly difficult for species in remote areas, as accessing fish for hatchery propagation can take longer. Bull Trout Salvelinus confluentus has recently been listed as threatened in Alberta and is garnering greater consideration for artificial propagation. Currently, there are no active hatchery programs for Bull Trout, and historically, very few attempts have occurred with limited success. The goal of this research was to establish a laboratory population of Bull Trout and compare the effectiveness of delayed and same day fertilization when transporting gametes or embryos over large distances. Methods Here, eggs were either fertilized in the field prior to transport (field) or 1 d after transport (green). Both treatments were collected from Smith-Dorrien Creek, Alberta, and transported to Winnipeg, Manitoba, by airplane (approximately 1,300 km). Differences between treatments were tested using a binomial generalized linear model. Results Fertilization rates were similar and high (>99%) for both treatments, and our model did not detect a significant treatment effect. Although a significant treatment effect was not observed, the green treatment had 10% lower survival over the duration of the experiment. The greatest mortality rates were observed at the swim-up stage in both treatments. Conclusions Both methods had similar fertilization rates and high survival to the fry stage (green = 36% and field = 46%). The results suggest that both methods are viable options when transporting Bull Trout gametes or embryos long distances for species recovery and research purposes.