Data from: Environmental influences and ontogenetic differences in vertical habitat use of black marlin (Istiompax indica) in the southwestern Pacific

The black marlin (Istiompax indica) is a highly migratory billfish that occupies waters throughout the tropical and subtropical Indo-Pacific. To characterize the vertical habitat use of I. indica, we examined the temperature-depth profiles collected using 102 pop-up satellite archival tags deployed off the east coast of Australia. Modelling of environmental variables revealed location, sea-surface height deviation, mixed layer depth and dissolved oxygen to all be significant predictors of vertical habitat use. Distinct differences in diel movements were observed between the size classes, with larger size classes of marlin (greater than 50 kg) undertaking predictable bounce-diving activity during daylight hours, while diving behaviour of the smallest size class occurred randomly during both day and night. Overall, larger size classes of I. indica were found to use an increased thermal range and spend more time in waters below 150 m than fish of smaller size classes. The differences in the diving behaviour among size classes were suggested to reflect ontogenetic differences in foraging behaviour or physiology. The findings of this study demonstrate, for the first time to our knowledge, ontogenetic differences in vertical habitat in a species of billfish, and further the understanding of pelagic fish ecophysiology in the presence of global environmental change.

黑枪鱼（Istiompax indica）是一类高度洄游的旗鱼科鱼类，栖息于整个热带及亚热带印度洋-太平洋海域。为解析黑枪鱼的垂直生境利用模式，本研究对澳大利亚东海岸部署的102个卫星弹出式档案标签（pop-up satellite archival tags）所采集的温度-深度剖面数据进行了分析。环境变量建模结果显示，海域位置、海面高度异常、混合层深度以及溶解氧浓度均为垂直生境利用的显著预测因子。研究观察到不同个体大小组间的昼夜运动模式存在显著差异：体重超过50千克的大个体黑枪鱼在日间呈现出可预测的弹跳式潜水行为，而最小个体组的潜水行为则在昼夜均随机发生。总体而言，与小型个体相比，大个体黑枪鱼的水温耐受范围更广，且在150米以下水域停留的时间更长。不同个体大小组的潜水行为差异被认为反映了其觅食行为或生理机能的个体发育差异。据我们所知，本研究首次揭示了旗鱼科物种垂直生境利用的个体发育差异，并进一步加深了对全球环境变化背景下远洋鱼类生态生理学的认知。