Understanding olfactory and behavioural responses to dietary cues in age-1 lake sturgeon Acipenser fulvescens
Detection of environmental cues is essential for all vertebrates and is typically established by the olfactory epithelium and olfactory sensory neurons (OSNs). In fishes, microvillous and ciliated OSNs are the principal types, typically detecting amino acids and bile salts, respectively. Activation of OSN receptors by specific ligands initiate downstream signal processing often leading to behavioural responses. In this study we used electrophysiological and behavioural techniques to evaluate olfactory detection and behaviour in juvenile lake sturgeon Acipenser fulvescens in response to hatchery- and natural dietary cues. We hypothesized that electro-olfactogram (EOG) and behavioural responses would be dependent on diet type. We predicted that inhibition of the phospholipase C/inositol 1,4,5-triphosphate (PLC/IP3) secondary transduction pathway would reduce EOG responses to dietary cues and, inhibition of the adenylyl cyclase/adenosine 3,5-cyclic monophosphate (cAMP) pathway, would have no effect. Furthermore, we predicted a strong EOG response would be manifested in a change in behaviour. We observed that both the PLC/IP3 and cAMP pathways were significantly involved in the detection of dietary cues. However, EOG responses did not manifest to behavioural responses, although the foraging activity to the hatchery cue was significantly greater compared to the control. Our results support the notion that lake sturgeon raised in a hatchery and fed a commercial pelleted diet may become accustomed to it prior to release into the wild. Further, this study suggests that, in conservation aquaculture settings, lake sturgeon should be exposed to natural dietary cues prior to release as one strategy to promote food recognition.