Two-way habitat use between reefs and open ocean in adult greater amberjack: evidence from biologging data

We investigated the relationships between vertical movements and both oceanographic features and physiological factors in greater amberjack Seriola dumerili, which is a reef-associated predator in the East China Sea. S. dumerili in the coastal waters of eastern Taiwan were equipped with archival tags or pop-up satellite archival tags that recorded depth and temperature, resulting in a dataset covering a total of 1331 d from 12 individuals. To classify the vertical movement patterns of S. dumerili, we performed a hierarchical cluster analysis for the depth profile. We observed multiple vertical movement patterns. Around topographic features, S. dumerili showed short-step dives (averaging < 35 m) during both the daytime and nighttime. In contrast, S. dumerili in offshore areas showed diel vertical movements. S. dumerili occasionally performed frequent dives to approximately 150 m throughout the day. These movements may be related to foraging behaviors associated with changes in water depth. We further analyzed the response of the peri-toneal cavity temperature to variations in the ambient temperature in 7 S. dumerili with archival tags. The peritoneal cavity temperatures fluctuated according to the ambient temperature changes, indicating that the vertical movement of S. dumerili is limited by physiological con-straints for the maintenance of body temperature. Together, our results indicate that the vertical movement of S. dumerili may be affected by the trade-off between foraging and thermoregulation