Robust characterisation of the age structure, growth and recruitment of toothfish in the Macquarie Island and Heard Island and McDonald Islands fisheries

Between 2010 and 2012, AAD, Australian Fisheries Management Authority and Australian fishing industry provided funds to conduct high throughput ageing of toothfish otoliths. 5780 otoliths, collected during the 2000-2011 fishing seasons in Division 58.5.2 and outside the CCAMLR area at Macquarie Island were processed. The inclusion of these datasets have improved the estimates of key parameters population dynamics of toothfish including growth rates, mean recruitment levels and interannual variability, as well as allowing more precise estimates of the selectivity of the different fishing gears used in these fisheries. The inclusion of catch at age data is shown to substantially improve the precision of the stock assessment in Division 58.5.2 compared to a scenario using only catch at length data. The ongoing collection and processing of otoliths to allow the inclusion of population specific estimates of catch at age data remains a high priority for toothfish fisheries. A costing breakdown for otolith processing at the AAD indicates that initial set up of laboratory equipment and salaries are the main expense in developing an ageing program.