The Efficacy of Ultraviolet Sterilization for Sterilizing Tools Used for Surgically Implanting Transmitters into Fish

Telemety is commonly used throughout the world to examine the behavior of fish and transmitters are commonly surgically implanted into the coelom of fish.  This requires the use of surgical tools such as scalpels, forceps, hemostats and sutures.  When implanting several fish for large telemetry studies, it is common for surgical tools to be sterilized or at least disinfected between use so that pathogens are not spread among fish.  However, autoclaving tools can take a long period of time, and chemical sterilants or disinfectants can be harmful to both humans and fish and have varied effectiveness.  Ultraviolet (UV) radiation is commonly used to sterilize medical tools and water in aquaculture facilities.  However, this technology has not been widely used to sterilize tools used to surgically implant transmitters in fish.  To determine its efficacy for this use, a UV sterilizer was used to sterilize surgical tools that were exposed to four aquatic organisms that typically lead to negative health issues in salmonids.  These organisms included:  Aeromonas salmonicida, Flavobacterium psychrophilum, Renibacterium salmoninarum, and Saprolegnia parasitica.  Surgery tools were exposed to the bacteria by dipping the tips of the forceps into a confluent suspension of three varying concentrations.  After exposure to the pathogen culture, tools were placed into a mobile Millipore UV sterilization apparatus.  The tools were then exposed for three different time periods; 2, 5, or 15 min.  After exposure to the UV light, the forceps were rinsed with sterile nutrient broth into sterile culture tubes and allowed to incubate at each pathogens appropriate temperature and time period.  The only growth that occurred happened in the positive control groups that were not exposed to UV light.  No evidence of pathogen growth was evident after exposure to UV sterilization.  This technique appears to provide a quick alternative to other sterilization techniques that may be less harmful to both humans and fish while not producing chemical waste.