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Abstract
Currently, there are no sedatives approved by the U.S. Food and Drug Administration that are considered effective, safe to a broad range of fish species, practical to use, and allow sedated fish to be returned to public waters immediately upon recovery. Availability of such a sedative is critical for many field-based fisheries activities and research, particularly when working with federally listed threatened and endangered species such as Pallid Sturgeon Scaphirhynchus albus. Therefore, we conducted an experiment to quantitatively compare induction and recovery times of Pallid Sturgeon sedated using tricaine methanesulfonate (MS-222), eugenol, or electrosedation (pulsed DC) and assess the fish’s hematological profile following sedation. Induction times varied significantly among the sedatives evaluated, of which electrosedation yielded the fastest induction times (0.2 ± 0.04 min, mean ± SE) followed by MS-222 (1.8 ± 0.19 min) and eugenol (2.3 ± 0.26 min). Times to recovery of equilibrium and responsiveness to tactile stimuli also varied, ranging from 1.4 ± 0.1 min for electrosedation to 4.7 ± 0.2 min and 6.4 ± 0.7 min for MS-222 and eugenol, respectively. Except for plasma osmolality, hematological variables (hematocrit, glucose, lactate, and cortisol) did not vary over a 6-h postsedation sampling period. Osmolality was lower in fish sedated with MS-222 and eugenol and higher in electrosedated fish compared with unsedated reference fish. Our results showed that all sedation protocols tested effectively sedated Pallid Sturgeon, all sedated fish recovered, and there was no delayed mortality associated with sedation.
Received April 21, 2015; accepted December 21, 2015 Published online May 24, 2016
Acknowledgments
We thank Smith-Root, Inc., for providing access to a portable electroanesthesia system, and Brian Gause and Bonnie Mulligan for their assistance with data collection.