Chemoreception of taurocholate in anosmic and sham-operated cod, Gadus morhua.

This study investigated the role of the olfactory system in cod, Gadus morhua L., on the general activity level and the responses to the bile salt taurocholate. Ten cod were rendered anosmic by section of the olfactory tracts, while another 10 control fish were sham-operated. The cod were stimulated in a seawater olfactometer which permitted reproducible administration of diluted samples of taurocholate at 5 concentration levels. The activity scores for both groups of cod increased with increasing concentrations of taurocholate. The detection threshold in the sham-operated cod for taurocholate was 7 nM, while the anosmic cod detected the presence of taurocholate at 70 nM. Taurocholate induced orienting reaction and snapping, both in sham-operated and in anosmic cod, indicating convergence of olfactory and other chemosensory pathways to nerve centers mediating these kinds of behavior. The bottom food search was observed only in the control fish. The seawater blanks induced a lower total activity score in the anosmic than in the sham-operated cod, which suggests that the olfactory input augments the general activity level.