Comparison of methods for anaesthetizing Senegal sole (Solea senegalensis) before slaughter: Stress responses and final product quality

The aim of this work was to evaluate several anaesthetization methods such as clove oil, hypothermia and asphyxia in Senegal sole (Solea senegalensis), a highly resistant species to hypoxic conditions. The overall intent of the study was to determine a method that minimizes pre mortem stress and maximizes final product quality in sole for market sale. Several pre and post mortem indicators were considered for this study, namely rigor mortis, muscle pH, ATP/IMP ratios, eye refraction index and sensorial attributes. In addition, the stress experienced by the fish pre mortem was assessed by measuring cortisol, glucose and osmolality levels in blood plasma just after death (post mortem). Based on these physiological indicators, the results revealed that of the three methods considered, 1 ml·L− 1 clove oil was the best method for stunning sole because it not only ensures a good final quality product, but also is acceptable for a direct human consumption.