The life cycle of the nine-spined stickleback Pungitius pungitius from Airolo Lake, Alaska, was studied using samples taken during 1993–1994 and 1997–1998. Pungitius pungitius was actively reproducing in late May and ceased reproductive activities by late June. Spawning adults were 2+ years old. Contrary to an earlier report, the data indicate that an individual female oviposits all of her ovulated eggs (i.e. an entire clutch) into a male's nest during one spawning episode. There was a trade-off between clutch size and egg size without concomitant variation in clutch mass between two years. The results are compared to those from other studies.