Age and growth of the tropical nearshore loliginid squid Sepioteuthis lessoniana determined from statolith growth-ring analysis

Age and growth parameters of the tropical loliginid squid sepioteuthis lessoniana in eastern Australian waters were determined from statolith growth-ring analysis. Juvenile specimens were captured, maintained alive, and their statoliths were chemically makred in situ with either tetracycline or calcein. These chemicals produced a flourescent mark within the statolith microstructure when viewed under UV light. Statoliths were mounted in thermoplastic cement and subsequently ground and polished. This process allowed rings to be visualized without any further preparation. It was thus possible to validate that distinct statolith rings were formed daily and that less-distinct thinner rings were, in fact, subdaily rings. The results of the age analysis of field-captured individuals revealed that the population of S. lessoniana in the study area grows at a very fast rate. Maturity in both sexes was achieved in less than 100 days. All specimens aged were less than 6 months old. The size of large individuals was within the range of S. lessoniana captured in other areas, with size ranges being 75-213 mm and 75-184 mm for males and females, respectively. Growth rates determined for S. lessoniana based on statolith ageing are considerably different from previous estimates based on length frequency data