Results of 2016 pop-off satellite archival tagging of Antarctic toothfish in the Ross Sea region

In 2016, scientists from the USA and New Zealand undertook a collaborative initiative to deploy pop-off satellite archival (PSAT) tags on Antarctic toothfish (Dissostichus mawsoni) on the southern shelf (SSRUs 88.1M,J,L) and northern seamount (SSRUs 88.1B,C) areas of the Ross Sea region. The objectives  were to characterize movement and habitat preferences, compare two different commercially available types of PSAT tags, and to develop methods to support research and monitoring of the Ross Sea region Marine Protected Area. All fish were tagged as part of research longline efforts under CM 24-01 after the 2015/16 toothfish fishing season had ended. A total of 10 PSAT tags from two manufacturers were released on the southern Ross Sea shelf in the austral summer, and 5 PSAT tags were released on the northern seamounts in the austral winter, for a total of 15 PSAT releases. Of the 10 PSAT releases in the southern Ross Sea, data from two tags were reported via Argos (one with full data, one with partial). On the northern seamounts, two of 3 PSAT tags scheduled to pop-off on February 1, 2017 reached their housing crush depth (1800 m) shortly after they were released. Although some useful data was collected during this experiment, data recovery in general was poor. As this is a developing technology proposed to be implemented by a number of Members, we suggest that additional work, including product development, is urgently needed to develop best practice guidance for tagging toothfish with PSAT tags.