Physiological Stress Responses to Prolonged Exposure to MS-222 and Surgical Implantation in Juvenile Chinook Salmon

摘要

This study simulated large-scale monitoring program operations to evaluate the responses of age-1 Chinook Salmon Oncorhynchus tshawytscha to tricaine methanesulfonate (MS-222; 80 mg/L) exposure and intracoelomic acoustic microtransmitter implantation. The MS-222 exposure effects and appropriate exposure times for juvenile Chinook Salmon undergoing intracoelomic implantation were determined using blood analytes (Na+, K+, Ca2+), blood pH, plasma cortisol, and survival immediately following anesthetic exposure (3, 6, 9, and 12 min on day 0) and over a recovery period (days 1, 7, and 14). In addition, effects were examined in surgically implanted and nonimplanted fish (but exposed to MS-222 for 3 min) over a 14-d recovery period. Regardless of anesthetic exposure time, there were no mortalities during exposure on day 0 or over the recovery period. On day 0, MS-222 exposure treatments of 9 and 12 min resulted in significantly higherNa(+) and Ca2+ and lower K+, indicating a reduced ability to maintain osmotic balance; however, MS-222 effectively dampened the cortisol release following surgical implantation and anesthetic exposure. Cortisol concentration was significantly higher in surgically implanted fish than in those not surgically implanted over the recovery period. Given these results, we recommend MS-222 exposure (80 mg/L) times of 6 min or less for compliance programs and studies involving age-1 Chinook Salmon. In addition, we recommend for other monitoring programs, regardless of species, that maximum MS-222 exposure times are implemented to minimize stress and surgical effect and that exposure times are specific to a species' life stage to prevent overexposure and long-term effects. Furthermore, the knowledge of effects and the development of maximum exposure times are beneficial for hatchery programs, fish barging or transportation programs, and most studies in which fish behavior and physiological responses would need to be dampened using MS-222 without adverse side effects