Mate choice and cannibalism in a natural population of a stream goby, Rhinogobius sp.

Breeding ecology of the stream goby, Rhinogobius sp. LD (Large Dark), was i nvestigated under natural conditions. Males selectively courted females of similar size to lead them to the nests, whereas females followed courting m ales preferentially when the relative male size was greater. Male-male comp etition for a female was relatively infrequent and not severe. Developmenta l stages of eggs and egg numbers in one nest indicated that males receive 1 -3 clutches during one breeding cycle. Males guarding multiple clutches fre quently ate some of the eggs, but those guarding single clutches rarely did so. Gravid females in the nest also frequently cannibalized eggs laid by a previous female, probably in order to extend the area available for egg de position. Mate choice in this species is discussed in relation to paternal ability, limitation of available spawning area and the female-biased sex ra tio.