Comparison of MS-222 and Electronarcosis as Anesthetics on Cortisol Levels in Juvenile Atlantic Sturgeon

Invasive surgical procedures on sturgeon (family Acipenseridae) are sometimes conducted without anesthesia. We examined plasma cortisol concentrations in Atlantic Sturgeon Acipenser oxyrinchus exposed to the anesthetic MS-222 (tricaine methanesulfonate), electronarcosis, or no anesthetic 1 and 24h after a small incision mimicking an invasive procedure (tag implantation or laparoscopy). We also determined the feasibility of using electronarcosis in the field and the effect of salinity on electronarcosis. One hour after surgery under electronarcosis or MS-222 anesthesia, cortisol concentrations did not differ significantly from those in untreated controls but all three were significantly lower than the no-anesthetic group. There were no significant changes between 1- and 24-h blood cortisol concentrations. We recommend electronarcosis as a method to minimize stress in fish studies involving surgical procedures because it avoids the use of toxic chemicals and because induction and recovery are virtually instantaneous.