Periodic movements of Greenland turbot Reinhardtius hippoglossoides in the eastern Bering Sea and Aleutian Islands

Understanding movement patterns of fish provides a context for making sound management decisions related to these populations; archival tags can provide this information. To better understand the depth-specific behavior of Greenland turbot Reinhardtius hippoglossoides in the Bering Sea and Aleutian Islands region, 297 temperature and depth recorders (archival tags) were implanted in fish between 2003 and 2011; 22 tags were subsequently recovered (18 with usable data). Tagged fish were at liberty from 19 to 1859 days, traveled straight line distances from 7.8-513.3 km, experienced mean temperatures from 3.23 to 3.70 degrees C, and occupied mean depths ranging from 448 to 753 m. Tagged Greenland turbot occupied their maximal depths during January and February, and their shallowest depths from July to September. Six tagged fish that were at liberty more than two years exhibited annual periodicity in depths occupied. Diel vertical migration (DVM, or 24-h periodicity) was identified for 17 of 18 tagged Greenland turbot, ranging from 4.16 %-60.12 % of an individual fish's time-atliberty. Activity levels (average rate of depth change and daily depth displacement) were relatively low in the summer and fall and highest in the winter. Four tagged females and no males occupied depths and temperatures consistent with the cold pool (< 2 degrees C) on the eastern Bering Sea Shelf (< 200 m). Fish at liberty for multiple years showed consistency in depths, activity, and DVM among years. Predictable movements of Greenland turbot in the Bering Sea and Aleutian Islands region may influence the availability and in turn catchability of this species to stock assessment surveys and should be considered by fishery managers.