Evaluation of different concentration doses of eugenol on the behaviour of Nephrops norvegicus

• Eugenol can successfully be used as an anaesthetic for Nephrops norvegicus.
• A concentration of 900 μL/L was successful in inducing full anaesthesia in under five minutes.
• Recovery took less than thirteen minutes for all three concentrations investigated (300, 600, 900 μL/L).
• The ovigerous state and length of time in captivity had significant effects on time to reach full anaesthesia and recovery.
• Sedation stages could be observed from behavioural postures displayed by the individuals.

Eugenol was tested for use as an anaesthetic on Nephrops norvegicus at three different concentrations (300, 600, 900 μL/L). Monitoring included the time taken to reach each sedation stage. Sedation stage was assessed by passive behaviours and reaction to direct stimulation. A concentration of 300 μL/L induced full anaesthesia in 56% of individuals taking on average (median time seconds ± SD) 849 ± 200 s. Concentrations 600 and 900 μL/L induced full anaesthesia in 439 ± 143 s and 277 ± 117 s respectively. Recovery times were not significantly different with an average time of 689 ± 39 s. Ovigerous (berried) and freshly captured females took longer to reach full anaesthesia and were quicker to recover compared to non-berried and captive females. Eugenol can be used as an effective anaesthetic for this species.