A rapid onset, post-capture muscle necrosis in the Norway lobster, Nephrops norvegicus (L.), from the West coast of Scotland

A post-capture, abdominal muscle necrosis of rapid onset has been identifie d in Norway lobsters, Nephrops norvegicus (L.), captured off the West coast of Scotland. Economic losses, as a result of the mortality of these animal s in transport, were encountered by Scottish wholesalers during the summer and autumn of 1999. Affected animals show a characteristic whitening of ind ividual muscle fibres and fibre bundles of the abdomen within hours of capt ure, with a progression towards complete opacity of the abdominal musculatu re within a number of days. The pathology causes a loss of the normal funct ion of the abdomen; thus, preventing the normal 'tail flip' swimming. Elect ron microscopy failed to reveal any obvious causative agent but showed that affected tissue displayed a progressive disruption of sarcomere organizati on, loss of Z-line material, condensation of myofibrils and infiltration of necrotic regions by granulocytes. SDS-PAGE of affected muscle tissue showe d that there was a great reduction of most of the major contractile protein s. The condition most closely resembles idiopathic or spontaneous muscle ne crosis, a pathology previously reported from both wild and cultured crustac eans. Damage to the integument in conjunction with exposure to various stre ssors during and immediately after capture is the most likely cause of the pathology. The rapid onset of the pathology has implications for the post-c apture handling procedure for N; norvegicus and their subsequent vivier tra nsport to market. It may also be partially responsible for the high mortali ty rate of undersized N. norvegicus returned to the sea after capture and a erial emersion.