AN ELECTROPHYSIOLOGICAL STUDY ON THE EFFECTS OF PH ON OLFACTION IN MATURE MALE ATLANTIC SALMON (SALMO-SALAR) PARR

The olfactory responses of mature male Atlantic salmon (Salmo salar L.) parr to known odorants were studied after exposure of the olfactory epithelia to water of varying pH. Electrophysiological recordings from the olfactory epithelia indicated that the responses of fish to both testosterone and urine from ovulated female Atlantic salmon were significantly reduced at pH 5.5 and 4.5 and abolished at pH 3.5. Concentration response studies indicated that at pH 5.5 and 6.5 significantly higher concentrations of testosterone and urine were required to produce the same amplitude responses as controls. Both testosterone and urine have previously been shown to be important chemical cues elicting behavioural and physiological responses in Atlantic salmon. The results are therefore discussed in relation to the possible sublethal effects of acidification on reproduction and behaviour of Atlantic salmon and the effects on salmonid stocks.