THE ROLE OF URINE IN SIBLING RECOGNITION IN ATLANTIC SALMON SALMO-SALAR (L) PARR

The ability of Atlantic salmon (Salmo salar L.) parr to discriminate between the urine from sibling and non-sibling fish was studied by using electrophysiological and behavioural techniques. Urine was collected from four sibling groups of Atlantic salmon parr which had been reared separately. Urine from all four groups were potent odorants in the Atlantic salmon parr, eliciting responses that were recordable from the olfactory epithelium. However, the mean recorded responses were significantly greater in Atlantic salmon parr that were stimulated with the urine from sibling than from non-sibling fish. Urine from all four groups elicited display behaviour in the Atlantic salmon parr which often occurs during aggressive interactions between parr when defending territories. Atlantic salmon parr also moved towards the source of sibling urine but moved away from non-sibling urine. The results are discussed in relation to the role of urine and the adaptive significance of sibling recognition in the Atlantic salmon.