Evaluation of the efficacy of potential anesthetic agents on cuttlefish (Sepia pharaonis) juveniles

Abstract Anesthesia is often used to relieve stress and reduce mortality rates in aquaculture systems. Here, we assessed the efficacy of four anesthetic agents on cuttlefish (Sepia pharaonis) juveniles. Concentration-response trials were performed to evaluate the induction time and recovery period after short-term anesthesia. MS-222 (5−100 mg L−1) was unable to induce anesthesia in cuttlefish juveniles. Treatment of the cuttlefish with 0.2−3 ml L −1clove oil induced death. By contrast, the anesthetization of cuttlefish with magnesium chloride solution (0.0125−0.2 mol L−1) and ethanol (2.5−30 mL L−1) was successful and the cuttlefish recovered well. Analysis of water quality index during simulated transportation revealed that 0.0125 mol L−1magnesium chloride solution was effective for cuttlefish transport for at least 12 h. 1H NMR spectroscopy coupled with multivariate data analysis and univariate data analysis were performed to reveal the metabolites in the cuttlefish central nervous system influenced by MgCl2. A total of 23 metabolites including amino acids, carboxylic acids, choline, betaine, nucleosides and nucleotides were identified. Levels of isoleucine, leucine, valine, tyrosine and glutamate were altered following anesthetization. Magnesium chloride indirectly increased the content of the inhibitory neurotransmitter glycine. It also reduced the content of excitatory neurotransmitter Dopamine by increasing the content of tyrosine thereby achieving anesthetization.