Behavioural and electrophysiological responses to F-prostaglandins, putative spawning pheromones, in three salmonid fishes

Behavioural and electro-olfactogram (EOG) responses to synthetic F-prostaglandins (PGFs) were recorded in the three salmonids: brown trout Salmo trutta, lake whitefish Coregonus clupeaformis and rainbow trout Oncorhynchus mykiss. Exposure to 10(-8) M PGF(2alpha). and 13, 14-dihydro-PGF(2alpha), increased swimming activity in individually exposed brown trout in a flow-through tank. Digging and nest probing behaviours were further observed in brown trout females exposed to PGF(2alpha). Lake whitefish exposed to 10(-8) M PGF(2alpha) and 15-keto-PGF(2alpha) also increased their locomotion. In rainbow trout, the absence of behavioural responses to PGFs correlates with a lack of olfactory sensitivity to these chemicals. PGFs triggered behavioural responses distinct from the feeding stimulant in brown trout. EOG measurements demonstrated that brown trout were most sensitive to PGF(2alpha), with a threshold concentration of 10(-11) M. Lake whitefish were most sensitive to both 15-keto-PGF(2alpha). and 13,14-dihydro-PGF(2alpha). Cross-adaptation and binary mixture experiments suggest that only one olfactory receptive mechanism is involved in PGFs detection. The behavioural and olfactory responses observed with exposure to PGF(2alpha) and its metabolites suggest these compounds function as reproductive pheromones in brown trout and lake whitefish. (C) 2003 The Fisheries Society of the British Isles.