Seasonal long-distance migration of striped marlin associated with sea surface temperature in the western North Pacific

Abstract Striped marlins ( Kajikia audax ) are broadly distributed in tropical and temperate waters. However, their long-term movements in the western North Pacific remain poorly understood. To investigate these movements, 10 individuals (162–191 cm eye-to-fork length) were equipped with pop-up satellite archival transmitting tags and released in the northern East China Sea in August 2023. Nine tags successfully transmitted data after 9–241 days at liberty, including five that remained at liberty for 118–241 days. Tagged marlin remained in the northern East China Sea during summer–autumn, where high productivity may provide favorable foraging conditions, before initiating rapid southward movements exceeding 2,000 km (total travel distance: 2,836–7,719 km; mean horizontal speed: 16.6–82.7 km d − 1 ) from late November to early December. These departures coincided with a decline in sea surface temperature to approximately 21 °C, and tagged individuals rarely occupied waters cooler than this temperature. This study provides the first electronic tagging records of seasonal migration in striped marlin at the northwestern edge of their distribution range, showing that declining sea surface temperatures coincide with rapid southward movements and suggesting that seasonal cooling is an important environmental factor associated with the timing of seasonal migration.