Movements and Behaviors of Blue Marlin (Makaira nigricans) in Northwestern Pacific Ocean Examined Using Pop-Up Satellite Archival Tags

Blue marlin are highly migratory species and have a wide distribution ranging from~48°N to 48°S. To investigate their movement patterns, pop-up satellite archival tags (PSATs) were deployed on blue marlin using the traditional harpoon method of southeastern Taiwan (Taitung). Depth, temperature and ambient light data were recorded by the PSAT. In total, 10 black marlin were tagged from Feb 2010 to July 2013. Period of time that PSATs remain affixed on the animal ranged from 26 to 360 days-at-liberty. Linear displacements ranged from 58 to 1,529 km from deployment to pop-up locations. Diving depths ranged from the surface to~423 m and ambient water temperatures occupied ranged from 33.5°C to 6.8°C, and the distributions of time spent at depth were significantly different between day and night. Tagged blue marlin spent the majority of daytime in the surface mixed-layer to ~50 m , and at nighttime were exclusively confined to the surface. Depth distribution appeared primarily limited by an 8°C change in water temperature from the warm surface layer. Diel diving patterns at daytime and nighttime also suggested basking behavior. Blue marlin diving behavior makes them particularly vulnerable to surface fishing gears.