Effects of winter water quality conditions on Atlantic Salmon embryo mortality and deformity rates in the Serpentine River (New Brunswick, Canada)

Abstract

In-stream incubation of Atlantic Salmon (Salmo salar) embryos within artificial redds using Jordan/Scotty fish egg incubator boxes is an alternative to traditional hatchery-based incubation methods. Winter water quality conditions, such as temperature and dissolved oxygen vary within natural redds and influence wild embryo development and survival. The differences in landscape characteristics and in-stream habitat features at catchment-, reach-, and site spatial scales were investigated to determine how they influenced water quality conditions within the Serpentine River, New Brunswick. A total of 14,400 hatchery-fertilized salmon embryos were incubated within river substrates from November 2020 to January 2021. The proportion of embryo mortalities within our experiment was high (44.9%), but still within the range observed in the literature from other incubation experiments, and the proportion of embryo deformities between our sites was very low (2.7%). Despite variations in average water temperature, cumulative degree days, and coefficient of variation in dissolved oxygen (DO) concentration, none were statistically significant for explaining embryo mortalities or deformities. Patterns were, however, evident across sites showing trends towards a decrease in mortality with cumulative degree days, and an increase in deformities with greater variation in DO. Improving our knowledge on Atlantic Salmon incubation habitat supports future research and restoration opportunities for adaptation under a changing climate.