Sturgeon food searching behaviour evoked by chemical stimuli: a reliable sensory mechanism

Abstract

Summary Using behavioural assay, the effects of partial and complete long-time anosmization on the ability of sturgeon to respond to food odour were investigated. After the bilateral cauterization of olfactory rosettes it was found that juveniles of both stellate sturgeon, Acipenser stellatus [8–15 cm total length (TL)], and Russian sturgeon, A. gueldenstaedtii (9–20 cm, TL), do not respond to food odour (Chironomidae larvae water extract, 10 )4 –10 )1 gL )1 ) and glycine (100 lM) in the first month. Three and 6 months after bilateral cauterization, behavioural reaction and level of sensitivity to food odour were partially restored. The threshold concentration for Chironomidae larvae extract was 10 )2 gL )1 in stellate sturgeon, being two orders of magnitude higher than in intact fish. Fish, after unilateral as well as partial destroying (80–85%) of olfactory rosettes, revealed food searching behaviour and level of sensitivity to food extract, comparable to intact fish. Acipenser baerii, Siberian sturgeon juveniles (5– 20 cm, TL) 3 months after bilateral cauterization revealed extraoral taste responses for a higher number of free amino acids (17) than intact fish (14) out of 19 free amino acids tested. These findings suggest that the extraoral gustatory system is responsible for the restoration, to a certain degree, of the ability of fish to respond to food odour after anosmization. The sensory mechanisms of reliability for olfactory-mediated food searching behaviour in sturgeon are discussed.