The spawning habits of the sea ravenHemitripterus villosus were investigated by scuba diving at shallow rocky bottom sites around Bolshoi Pelis Island (Peter the Great Bay, Sea of Japan). Spawning occurs in September, when the surface water temperature drops. The optimum spawning temperature is 17–18°C. The fish density in nest sites reaches 120/300 m2. The mean individual fecundity is about 10000 eggs. Over 35% of the egg masses ofH. villosus are eaten by echinoderms, primarilyPatiria pectinifera andStrongylocentrotus nudus. Since fecundity is relatively low and parents do not take care of the egg masses, predation can strongly affect the abundance of this species.