Efficacy of 2-phenoxyethanol as an anaesthetic for the musky octopus, Eledone moschata (Lamarck 1799), (Cephalopoda: Octopodidae)

Abstract

The efficacy of 2-phenoxyethanol (2-PhOH) as an anaesthetic for the musky octopus, Eledone moschata (Lamarck, 1799), was examined. Different doses (1.0, 1.2, 1.4, 1.6, and 1.8 mL L^{-1}) of 2-PhOH were prepared in 20 L transparent plastic containers containing 10 L of continually aerated seawater (pH 8.2, O2 8 mg L^{-1}, salinity 37.2 per thousand at 15.3 °C). Six individuals were used in each experiment. After quantifying the anaesthetic time for each animal, which was defined as the loss of sucking intensity (Stage A3), the specimens were transferred to a plastic recovery tank (430 L of aerated seawater), defined as regular breathing (Stage R4; 12-13 breaths min^{-1}), where they were observed for 48 h to document any mortality. There were significant differences in induction and recovery time among the various 2-PhOH concentrations (ANOVA, P < 0.05). The musky octopus was anaesthetised effectively at 1.2, 1.4, and 1.6 mL L^{-1} of 2-PhOH (P > 0.05) and no mortality was observed within 48 h. However, 50% mortality occurred at 1 mL L^{-1}2-PhOH within 24 h after anaesthesia, and 100% mortality at 1.8 mL L^{-1} of 2-PhOH within 48 h. Based on the recovery time, a dose of 1.6 mL L^{-1} of 2-PhOH was considered the most effective dose for anaesthetising the musky octopus.