Sibling recognition and olfactory sensitivity in juvenile coho salmon (Oncorhynchus kisutch)

Previous experiments indicated that juvenile coho salmon (Oncorhynchus kisutch) can distinguish the chemical traces of siblings from nonsiblings of their own population. The present study confirmed the finding that coho salmon use chemoreceptor systems to distinguish tankmate siblings from nonsiblings that they have not been reared with. However, salmon did not distinguish siblings from nonsiblings or maternal half-siblings if they had been reared together. Electrophysiological experiments demonstrated that the olfactory sense of young coho salmon can detect certain amino acids and a bile acid at concentrations of about 10−8 to 10−9 M. Additional tests suggest that bile acids are probably of primary importance in chemically characterizing conspecifics and amino acids play a secondary role.