Depth and temperature preferences of Antarctica toothfish (Dissostichus mawsoni) from a pilot popup satellite archival tag study in the Mawson Sea

Data retrieved from five popup satellite-tagged Antarctic toothfish (Dissostichus mawsoni) released in the Mawson Sea were analyzed. Toothfish were at liberty for 36-366 days, and yielding yearlong, 15-second data records from a single, recaptured individual.  These fish occupied an overall depth range of 326 to 1824 m and a temperature range of -1.95 to 0.7°C.  Through available depth and temperature data, and albeit limited ability to accurately geolocate deep-diving toothfish, all tagged fish appeared to have remained in the Mawson Sea area for the majority of time at liberty. The recaptured individual exhibited distinctive vertical ascents only in September, during the presumed spawning season, and was estimated to be near shore in the Mawson Sea. These ascents could represent characteristic spawning behavior and suggested Mawson Sea is a potential spawning ground. Future investigation is warranted to observe similar ascents in other individuals, and be analyzed in the greater context of reproductive ecology of Antarctic toothfish. To this end, a tagging configuration is proposed to target logging of putative spawning behavior, and is recommended to put forward to the greater CCAMLR community as standard protocol for popup satellite tagging studies