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_2α and 13, 14-dihydro-PGF_2α 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_2α. Lake whitefish exposed to 10⁻⁸ M PGF_2α and 15-keto-PGF_2α 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_2α, with a threshold concentration of 10⁻¹¹ M. Lake whitefish were most sensitive to both 15-keto-PGF_2α and 13, 14-dihydro-PGF_2α. 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_2α and its metabolites suggest these compounds function as reproductive pheromones in brown trout and lake whitefish.