Anesthetic and sedative effects of plant-derived essential oils on red swamp crayfish (Procambarus clarkii) at different concentrations and temperatures

Abstract

Limited studies have been conducted on the use of anesthetic agents during handling, cooking, and transportation of crayfish species. This study was carried out to evaluate the anesthetic effects of clove (Syzygium aromaticum), spearmint (Mentha spicata) and chamomile (Matricaria chamomilla) essential oils on red swamp crayfish (Procambarus clarkii (Girard, 1852)) at temperatures of 17 and 23 °C. The study was performed in 10 L plastic containers filled with 3 L of dechlorinated freshwater to determine induction and recovery times and stages under laboratory conditions. Five concentrations (200, 350, 500, 750, and 1000 µL/L) of essential oils were used. This study found that the induction time at 1000 µL/L was significantly lower than 200 and 350 µL/L at 17 °C (p < 0.05) and there was no statistical difference between the five concentrations at 23 °C (p < 0.05). Recovery at 1000 µL/L was markedly higher than 200, 350, and 500 µL/L at 23 °C (p < 0.05). Red swamp crayfish exposed to clove oil reached Stage 6, which is identified as a total loss of equilibrium, using 1000 µL/L at both temperatures. For spearmint oil, induction time at 1000 µL/L was significantly lower than 200, 350, and 500 µL/L at 17 °C, induction time at 200 µL/L was the highest at 23 °C (p < 0.05), and Stage 5 (partial loss of equilibrium) was recorded as the maximum stage reached. Recovery time at 1000 µL/L was the highest at 17 °C, and recovery at 200 and 300 µL/L were lower than 750 and 1000 µL/L at 23 °C (p < 0.05). No significant differences were recorded in the induction and recovery times of chamomile oil for all the concentrations at both 17 and 23 °C (p > 0.05) and the crayfish reached a maximum of Stage 3 (deep sedation) at 1000 µL/L at 23 °C. Overall, clove and spearmint essential oils were proven to be the most successful at providing effective anesthesia to the red swamp crayfish. However, the length of induction and recovery times may be a disadvantage for some procedures. In addition, it has been revealed that chamomile oil may have only a sedative effect and is therefore unsuitable to be used as an anesthetic.

Keywords:
Carcinoculture; chamomile; eugenol; herbal anesthetics; spearmint