On the Female Sex Pheromones and Courtship Behaviour in the Salmonids, Oncorhynchus masou and O. rhodurus

Abstract

It was demonstrated that males of Yamame Oncorhynchus masou were able to discriminate post-ovulatory females from pre-ovulatory ones on the basis of a chemical cue. And also males of Amago O. rhodurus were able to discriminate between post-ovulatory females and pre-ovulatory ones on the basis of a chemical cue. Some important aspects derived from the experiments are listed as follows;
1. Post-ovulatory females of each species released a female sex pheromone respectively, which males detect by olfaction.
2. Female sex pheromone of each sepcies played some essential roles in the courtship behaviour of each species, such as informing males of the occurrence of ovulation in females, at-tracting males and eliciting persistent courtship of males.
3. Courtship behaviour of males of each species was elicited only by post-ovulatory females of their own kind. And males of each species discriminated post-ovulatory females of their own kind from those of other species by olfaction. Therefore the species-sepcificity of the pheromones was observed in the two salmonids.