Testosterone is a potent odorant in precocious male Atlantic salmon ( Salmo salar L.) parr

Abstract Electrophysiological recordings from the olfactory epithelia have shown that testosterone is a potent odorant in precocious male Atlantic salmon (Salmo salar L.) parr. However, the olfactory epithelia of these fish only appeared to be responsive for a limited period during the year (in O ctober). Immature fish did not respond at any time. The precocious male parr were unresponsive to a large range of other steroids, including testosterone glucuronide. Free testosterone was not found in the urine of ovulating female Atlantic salmon. The results are discussed in relation to the role of testosterone in the physiology of the salmon and its possible role as a behavioural pheromone.