Feasibility of using pop-up satellite archival tags (PSATs) to monitor vertical movement of a Sebastes: A case study

Pop-up satellite archival tags (PSATs) were deployed on eight blackspotted rockfish (Sebastes melanostictus) (37-54 cm fork length) caught in southeast Alaska at depths from 148 to 198 m. Six of these fish were tagged and released immediately after capture in a commercially available inverted, weighted crab ring, descended quickly to what was assumed to be the seafloor, and remained at that depth until the PSATs released early (after 12-14 days). The remaining two fish were held in a laboratory after capture, one for 8 months and one for 46 months, and were then released at the surface nearby the capture site. One of these two tags released after 12 days while the tag deployed on a 37 cm fish was retained for 190 days. Both fish moved to deeper depths initially and then moved back to more shallow depths, indicating that rockfish may require time to acclimate to increased pressure if the swim bladder is not currently ruptured. For the tag that was retained for 190 days, we identified six phases of vertical movement behavior. During the longest phase (122 days) the fish made rapid descents, sometimes in less than 15 min, which were deeper during the day and during high-tide, but more frequent at night. During some of the shorter phases (lasting from 8 to 28 days) the fish was more sedentary or was deeper at night. Our results show that it is possible to tag a deepwater rockfish with a PSAT.