Effects of clove oil, tricaine, and CO2 on gamete quality in steelhead and white sturgeon

This study examined the direct impact of three commonly used anesthetics-clove oil (86% eugenol), tricaine (tricame methanesulfonate [MS-222]), and CO2-on egg quality for steelhead Oncorhynchus mykiss and that of clove oil and tricaine on the motility of sperm from both steelhead and white sturgeon Acipenser transmontanus. Exposure of unfertilized eggs for 6 or 24 h to 150 mg clove oil/L, 225 mg tricaine/L, or less than 100 mm Hg CO2 resulted in no reduction in egg fertility or embryo survival to batch. However, higher doses (1,500 mg clove oil/L; 2,250 and 22,500 mg tricaine/L; or more than 125 mm Hg CO2) negatively impacted egg quality. Similarly, a 3-h exposure to clove oil (150 mg/L) or tricame (225 mg/L) produced no significant effect on sperm motility in steelhead. White sturgeon sperm showed a modest decline in motility after incubation in clove oil. Thus, the data suggest that clove oil and tricame can be used on fish prior to gamete harvesting without significant adverse impacts on gametes. Although CO2 is unlikely to have deleterious effects on eggs, CO2-associated declines in ovarian fluid pH may be of concern when ovarian fluid pH is used as an indicator of egg quality.