1Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, University of Georgia, Athens, GA, USA; 2Warm Springs Regional Fisheries Center, U.S. Fish & Wildlife Service, Warm Springs, GA, USA; 3Channel Islands Marine and Wildlife Institute, Santa Barbara, CA, USA
Two projects involving endoscopy of sturgeon have been undertaken as a collaborative research effort between the College of Veterinary Medicine, University of Georgia and the United States Fish & Wildlife Service, Warm Springs, Georgia.
The first project involved seventeen Gulf of Mexico sturgeons (Acipenser oxyrinchus desotoi) that underwent endoscopic sex determination, gonadal biopsy, and various reproductive surgeries as part of a conservation development plan.1 The fish were anesthetized with tricaine methanesulfonate (MS-222) buffered with sodium bicarbonate and maintained on a recirculating water anesthesia circuit. A 6-mm Ternamian EndoTIP cannula, placed through the ventral midline, midway between pectoral and pelvic fins, permitted the introduction of a 5-mm telescope. Swim bladder aspiration and CO2 insufflation of the coelomic cavity provided excellent visualization. Second and third cannulae were placed under direct visual control lateral and cranial or caudal to the telescope cannula. Sex determination was successfully performed in all fish; however, five of 17 sturgeons (29%) required endoscopic gonadal biopsy to confirm sex. Bilateral ovariectomy or orchidectomy was successfully performed in three males and four females. Unilateral ovariectomy and bilateral ligation of the Müllerian ducts using an extracorporeal suturing technique was accomplished in an additional three females. No apparent morbidity was associated with the anesthesia or endoscopic surgery in any fish.
A second, more invasive surgical procedure was undertaken in 12 female short-nosed sturgeon (Acipenser brevirostrum). These fish were first subjected to a visual appraisal of their reproductive tract, and any fish undergoing major reproductive activity were removed from the study. In 10 sturgeon, bilateral ovariectomy and Müllerian duct ligations using intracorporeal and extracorporeal techniques were employed. At the time of writing these fish were still recovering from their endoscopic procedures; however, plans for radio transmitter implantation and release are anticipated.
Minimally invasive endosurgery in fish offers exciting possibilities and might have significant applications in fish management, research, and conservation.
1. Hernandez-Divers, S.J., R.S. Bakal, B.H. Hickson, C.A. Rawlings, G.H. Wilson, M. Radlinsky, S.M. Hernandez-Divers, and S.R. Dover. 2004. Endoscopic sex determination and gonadal manipulation in Gulf of Mexico sturgeon (Acipenser oxyrinchus desotoi). J. Zoo. Wildl. Med. 35: 459–470.