Clove oil as an anaesthetic for adult sockeye salmon: field trials

Wild migrating sockeye salmon Oncorhynchus nerka exposed to 20, 50 and 80 mg 1 −1 of clove oil could be handled within 3 min, recovered within 10 min, and survived 15 min exposure trials. Fish tested at 110 mg 1 −1 did not recover from 15 min exposure trials. Response curves developed for induction and recovery time considered the following predictors: clove oil concentration, sex, fish length and depth. A significant positive dependence was observed between induction time and fish length for 20, 50 and 80 mg 1 −1 test concentrations; no dependence was observed between induction time and length at 110 and 140 mg 1 −1 . Recovery time differed as a function of clove oil concentration, but not fish size. A concentration of 50 mg 1 −1 is recommended for anaesthetizing sockeye salmon ranging in length from 400 to 550 mm at water temperatures averaging 9–10° C.