Update of 2-year tagging program for skates in the Ross Sea region

A 2-year programme was implemented in the 2019/20 and 2020/21 fishing seasons in the Ross Sea region to tag and release skates for population size estimation and to validate the thorn ageing method for Antarctic starry skate (Amblyraja georgiana). The program has been largely successful to date, with a total of 8,506 skates tagged and released over the past two seasons in the Ross Sea region, with a further 484 individual skates voluntarily tagged in the Amundsen Sea Region. Recaptures from these releases will be used to monitor trends in population size through time with additional tagging occurring periodically. In addition, 2,117 skates that were tagged and released in the 2019/20 season on Australian, Spanish, New Zealand, and United Kingdom vessels were also injected with either oxytetracycline hydrochloride or strontium chloride in order to incorporate chemical marks into the caudal thorns for age validation. A total of 44 skates tagged during the program have been recaptured to date. Results from the age validation experiments, as well as those of biological and movement analysis, will be provided to future WG-FSA meetings. Tagged skates recaptured on all vessels in the Ross Sea region in future fishing seasons should be biologically sampled and a selection of caudal thorns removed and frozen, and returned to NIWA, Wellington, for subsequent laboratory analysis.