USE OF ELECTROPHYSIOLOGICAL TECHNIQUES IN EVALUATING EFFECT OF TAURINE DEFICIENT DIET ON OLFACTORY FUNCTION IN SABLEFISH Anoplopoma fimbria

The sense of smell is important to fish, connecting them to the environment by relaying chemical information that plays a role in triggering behaviors associated with feeding, predator avoidance, reproduction and migration. Understanding how fish respond physiologically to different odors can help inform what components are beneficial in inducing these behaviors, and how factors such as diet and ambient water chemistry may affect the functioning of the olfactory system.

Elecrophysiological techniques make it possible to measure physiological responses to various substances. Amino acids are essential nutrients and are important stimulants of searching and feeding behaviours. Sensitivity to different types of amino acids has been shown in fish and varies among species. Using the electro-olfactogram (EOG) and the electroencephalogram (EEG), it is possible to measure the neurological responses to these compounds at the receptor sites in the olfactory bulb.

Development of alternative, terrestrial plant-based feeds raises issues with the proper balance of essential amino acids. Taurine functions very similarly to an amino acid and is absent in plant proteins. The figure shows an example of how electrophysiological techniques can be used to study a diet lacking in taurine.

In this pilot experiment, Sablefish were fed diets with either 0% or 1.5% taurine, or a reference diet. Fish receiving the diet with 0% taurine tended to have EEG responses that were shorter in duration than diets with taurine.

Taurine plays a part in a variety of physiological functions. Altered olfaction responses from taurine deficiency may be an indicator of further systemic problems.