MATING SYSTEM AND SPAWNING CYCLE IN THE BLENNY, ISTIBLENNIUS-ENOSIMAE, AT KAGOSHIMA, JAPAN

Field observations on reproductive ecology and territoriality of the b lenny Istiblennius enosimae, were made in a tidepool at Hanaze Beach, Kagoshima Prefecture, Japan during the summer of 1988. This blenny was herbivorous, and nesting males (> 73 mm SL) maintained territories ar ound nest sites, which were located in rocky crevices of the tidepool. Males courted females wandering near their nests, and spawnings coinc ided with neap tides. Males guarded the eggs until the embryos hatched at following spring tides. It was suggested that this semilunar spawn ing cycle guarantees a maximum dispersal of newly hatched embryos away from natal tidepool. Male reproductive success was related to large b ody size and/or large nest size. There is a size-assortative relations hip between male and female among pairs. Egg predation rates by fishes , crabs and sea urchins were not correlated with the body size of male blennies.