An assessment of the nutritional, physiological and health condition of brindle and red adult Jasus edwardsii rock lobsters and their survival after extended emersion exposure

There is a widely held perception within the industry that Jasus edwardsii rock lobsters from deeper areas (brindle colour) have greater mortality rates than shallow-water, red-coloured lobsters. Mortality events in Tasmania occur mainly around the time of season openings in mid-November and price often falls sharply at this time because of the combined effect of increase in supply and damage to market reputation that occurs when impacted shipments are received. This study aimed to determine if there were any differences in condition between brindle and red lobsters that could affect lobster’s vulnerability related to extended emersion exposure at the start of the 2015 fishing season. Three trials were conducted in which lobsters were exposed to an emersion period of 64 hours. Non-invasive haemolymph indicators of nutritional (Brix index, protein, triglyceride), physiological (haemocyanin, metabolites, electrolytes and minerals) and health (total haemocyte count and carotenoids) condition were examined. No effect of lobster colour on condition and the vulnerability to emersion was found. Nutritional and health indicators were not useful predictors of lobster vulnerability but the concentration of calcium, bicarbonate and haemocyanin in the haemolymph were significant predictors of survival. The nutritional condition of both brindle and red lobsters during the study period was found to be better than published data from previous years suggesting clear inter-annual variation in the timing of moulting or post-moult recovery time. Further research targeting specifically low condition lobsters vulnerable to transport stress is needed to develop a non-invasive predictor of transport vulnerability.