Submitted to: Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/3/2003
Publication Date: 6/1/2004
Citation: Davis Jr, K.B., Griffin, B.R. 2004. Physiological responses of hybrid striped bass under sedation. Aquaculture. 233:531-548. Interpretive Summary: Very low concentrations of several aquatic anesthetics were evaluated for their effectiveness in reducing stress in sunshine bass. Clove oil, Aqui-S, metomidate, MS-222, quinaldine and quinaldine sulfate were used alone or combined with 5 g/l NaCl, and the fish evaluated after exposure and to stress during exposure. The stress was imposed by lowering the water in the aquarium for 15 minutes and the stress response was evaluated by measuring plasma cortisol, glucose and chloride concentrations before during and after recovery from the chemicals and stress. Exposure to all the compounds tested, except metomidate, resulted in an increase of cortisol stress increased the response. Plasma glucose was not markedly changed after exposure to the test compounds but was increased after stress. The cortisol response to sodium chloride was transient and returned to control levels after 30 minutes, but this salt did not lower the stress response. No consistent changes in plasma chloride were apparent. Similar results were observed when the test compounds were combined with sodium chloride. Metomidate may have some promise in reducing the cortisol response to stress in fish; however, only MS-222 and sodium chloride are presently approved for use in aquaculture, and neither reduced the cortisol or glucose response.
Technical Abstract: Several aquatic anesthetics provided in doses low enough not to change the swimming behavior alone and in combination with NaCl were evaluated for their effectiveness to suppress the stress response in sunshine bass (Morone crysops X M. saxatilis). Clove oil, Aqui-S, metomidate, MS-222, quinaldine, and quinaldine sulfate were used alone or combined with 5 g/l NaCl. The stress response was evaluated by measuring plasma cortisol, glucose and chloride concentrations in fish after exposure to each of the compounds and after exposure in fish subjected to stress while exposed to each of the compounds. Stress was induced by lowering the water in the aquarium for 15 min. Exposure to all of the compounds, except metomidate, resulted in a significant increase in plasma cortisol and glucose. The cortisol increase induced by exposure to NaCl alone was transient, but salt did not reduce the response due to stress. The same pattern of response occurred when the anesthetics were given with NaCl. Only exposure to quinaldine resulted in an increased glucose concentration and plasma glucose was higher than controls in stressed fish exposed to clove oil and quinaldine sulfate. Metomidate may have promise in suppressing the stress response in hybrid striped bass; however, the only approved anesthetic for use in food fish is MS-222. Exposure of fish to MS-222 induced the stress response and did not suppress the magnitude of the stress response in fish exposed to low water stress. These data point out the importance of continuing to develop and approve compounds for use in aquaculture.