Biology of Lake Sturgeon Spawning Below a Dam on the Richelieu River, Quebec: Endocrinology, Behaviour, and Egg Deposition

Knowledge of the reproductive biology of wild populations of sturgeon is critical to ensure the perpetuation of this unique group of animals. We combined intensive netting surveys, non-lethal blood sampling, radio telemetry and egg collection to examine the reproductive biology of lake sturgeon (Acipenser fulvescens) at a suspected spawning ground below a dam on the Richelieu River, Quebec, Canada. Using the aforementioned techniques we quantified and described the timing of spawning, the characteristics and location of a spawning ground, the composition and residency of reproductive and non-reproductive individuals, and temporal trends in reproductive hormone titers. Lake sturgeon were present at the site when sampling began at the start of May, however spawning was not detected until 30 May, with back calculated embryonic ageing indicating that spawning took place from 26 May – 5 June when water temperature averaged 13.4 ± 0.1^oC (range 11.5–15.5^oC). We estimated the spawning population at 1629 individuals (1129–2452; 95% C.I.). These results indicate that suitable spawning habitat for lake sturgeon exists downstream of a dam equipped with a fishway and have important implications for passage which will be discussed in the broader context of sturgeon fishway passage.