Stress in Female Lake Trout (Salvelinus namaycush) Before Spawning Alters Offspring Cortisol and Growth

Catch-and-release angling (C&R) is a conservation strategy that assumes released fish survive and contribute to populations. However, C&R stress, particularly during spawning, may impact reproductive females and their offspring, such as changes in maternal offspring investment. Here, we studied the effects of maternal stress on lake trout (Salvelinus namaycush), a heavily targeted C&R species, and their offspring. Females were angled, blood sampled, and either held for 48 h (Bag), or held for 48 h and air-exposed every 12 h to mimic repeated C&R events (Air+Bag). A third group of fish (Control) was not held and sampled immediately after capture only (Control). Females in bagged treatments were again blood sampled after 48 h to determine stress indices (cortisol, glucose, and lactate). Following treatment, fish were euthanised and eggs were collected and incubated for 69 days post-fertilization (DPF). Eggs and larvae were temporally analyzed for cortisol, macromolecular contents (glycogen, protein, water, and lipids), and morphometrics (wet mass, dry mass, and length). Maternal cortisol levels increased in bagged treatments, showing deviation in the stress response. Similarly, in these treatments, egg cortisol was elevated at 3 and 12 DPF, and in larvae at 69 DPF. While there were limited changes in macromolecular contents between treatments, the Air+Bag treatment demonstrated increases in egg and larval mass, as well as longer larvae at 69 DPF. These findings suggest maternal stress impacts the stress axis and morphometric development in lake trout offspring. However, the long-term implications of altered larval stress response and growth on lake trout populations remain unclear and a critical area of future work to develop sustainable recreational fisheries.