Effects of the first two months of ranching on the health of southern bluefin tuna Thunnus maccoyii

A weekly monitoring project was designed to improve our understanding of the dynamics of southern bluefin tuna health, immune response, and performance during the first two months of ranching. In addition, results were compared to the data for wild fish to highlight any effects of captivity. Weight, length, condition index, hemoglobin concentration, and immune response were all found to change significantly over this period. SBT were found to be relatively healthy prior to a mortality event which resulted in a cumulative mortality of 8.5%. The mortality event was associated with decreased hemoglobin concentrations and changes in immune response.