Migratory Behavior for Black Marlin (Istiompax indica) and Blue Marlin (Makaira nigricans) in Northwestern Pacific Ocean

To investigate black marlin and blue marlin movement patterns, pop-up satellite archival tags were deployed on blue marlin using harpoon and longline fishery of southeastern Taiwan (Taitung). In total, 9 black marlin and 15 blue marlin were tagged from Feb 2010 to May 2014 and PSATs remain affixed on the animals ranging from 10 to 360 days. Linear displacements ranged from 73 to 3,579 km from deployment to pop-up locations with average speeds of 0.1 to 5.7 km hour^-1. Our horizontal movement tracks suggest that black marlin undergo distinct seasonal movement patterns: fishes tagged in spring and summer moved in a northerly direction to the East China Sea and those tagged in winter season moved in a southerly direction to the South China Sea. And blue marlin have not seasonal movement patterns, tracks from the longest deployments revealed highly variable movement patterns, regardless of tagging location or season of release. Diving depths ranged from the surface to ~258 m for black marlin, and surface to ~441 m for blue marlin. In the context of regional fisheries management and stock assessments, our study reports the first tagging data of wild black marlin and blue marlin in northwestern Pacific Ocean.