Movement and habitat use of striped marlin Kajikia audax in the Western Indian Ocean

• Published in: Journal of fish biology 2020-11, Vol.97 (5), p.1415-1427
• Main Authors: Rohner, Christoph A., Bealey, Roy, Fulanda, Bernerd M., Pierce, Simon J.
• Format: Article
• Language: English
• Subjects: Africa, Eastern; Animal Migration; Animals; billfish; biotelemetry; Chlorophyll; Chlorophyll a; Commercial fishing; Conservation of Natural Resources - methods; Distance; Ecosystem; Electrophoretic mobility; Fish; Fisheries; Fisheries management; Fishery data; Fishing; Fishing areas; Fitness Trackers - veterinary; Habitat selection; Habitat utilization; Hot spots; Indian Ocean; Indian Ocean Islands; Kajikia audax; movement ecology; Overfishing; Perciformes - physiology; Prey; Remote sensing; Remote Sensing Technology - veterinary; Satellite Communications; satellite tag; Satellite tracking; Satellites; Sea surface; Sea surface temperature; Seasons; Somalia; Stock assessment; Surface temperature; Sustainability; Swimming; Tagging
• ISSN: 0022-1112; 1095-8649
• DOI: 10.1111/jfb.14508

Striped marlin Kajikia audax are globally Near Threatened and their stock in the Indian Ocean was last assessed as “overfished and subject to overfishing”. Significant gaps in our understanding of their ecology remain, hampering the efforts of fisheries managers to ensure stock sustainability. There is a particular lack of fisheries‐independent data. Here we present the results from the first large‐scale satellite tracking study of K. audax in the Indian Ocean. We tagged 49 K. audax with pop‐up archival satellite‐linked tags off the Kenyan coast from 2015 to 2019. Individuals were highly mobile, covering horizontal distances of up to 9187 km over periods ranging up to 183 days, with a mean daily distance of ~48 km. Long‐distance movements were recorded to the east and north of East Africa, with the most distant tracks extending north to the Arabian Sea and east to near the Maldives. None of the K. audax swam south of East Africa. Kernel utilization distributions of fish locations demonstrated their shifting seasonal activity hotspots. Over the sport‐fishing season (and tagging period) in Kenya, from December to March, K. audax typically stayed off the East African coast. After March, the activity hotspot shifted north to a region close to the Horn of Africa and Socotra Island. Remotely sensed sea surface temperature and chlorophyll‐a maps indicated that this seasonal movement could be driven by a shift in prey availability. Our results show the high mobility of K. audax in the Western Indian Ocean, and that individuals seasonally range between two major fishing areas.