Matures at increasing ages with increasing latitude (Ref. 88171). Both sexes do not spawn yearly and spawning intervals may vary according to area. In the St. Lawrence River, males spawn every 1-5 years, females every 3-5 years (Ref. 89103). Adults from the sea begin to ascend the lower reaches of large rivers in spring with the majority ascending immediately prior to spawning. Spawning occurs between March and August (Ref. 59043), when water temperature is 13.3-17.8 °C (Ref. 89118). Spawning occurs over bedrock, boulders or gravel bottoms, in depths exceeding 10 m at current velocities of 0.5-0.8 m/s (Ref. 59043, 89103). Exact time of spawning depends on temperature (Ref. 26938). Per female 0.4-8 million eggs may be spawned (Ref. 45706, 84845, 89137). Eggs demersal, sticking to stones, measuring 2.55 mm in diameter and hatching in 1 week at 17.8 °C (Ref. 4639, 9980). Adults return to the sea after spawning (Ref. 59043). Sturgeons in general have a high capacity for hybridization and most species are able to cross-breed (Ref. 89103, 89117).