Midwest Fish & Wildlife Conference 2019

AUTHORS. Margaret Thomas, Eastern Illinois University; Anabela Maia, Rhode Island College; Eloy Martinez, Eastern Illinois University; Robert Colombo, Eastern Illinois University

ABSTRACT. The process of sedating fish is necessary for a variety of procedures in research and within field or laboratory settings. Information regarding chemical sedatives, such as MS-222 (99.5% tricaine methanesulfate), suggests that it is often insufficient for field use due to extensive recovery time and withdrawal. Subsequently, alternatives to chemical sedatives are being explored, of which electronarcosis is a popular option. Electronarcosis applies particularly to “immediate-release” situations, as it is found to have rapid recovery times and minimal lasting effects on fish. Few studies provide an overview of the effects of sedation on its subjects, and large gaps remain with regard to the species-specific responses to the treatment. Therefore, we sought to compare the short-term physiological effects of bluegill sunfish (Lepomis macrochirus) subjected to electronarcosis and MS-222 sedation techniques. We hypothesize that sedation achieved by electronarcosis will provide an overall decreased stress response in its subjects. Bluegill sunfish were exposed to species-specific doses of MS-222 or electrical stunning to achieve complete sedation. Immediately following sedation, basal metabolic rates of fish were monitored with indirect calorimetry. Basal metabolic rates were employed as indicators of aerobic physiological activity on fish. Cortisol levels in blood were assayed after metabolic screening and gathered over a period of 1, 2, 4, and 6 hours following treatment on each group and compared to a pre-treatment control. Plasma cortisol levels and metabolic rates are expected to have an overall decreased value in subjects treated with electrosedation, deeming it a more practical alternative to chemical treatments.