Findings from 111 satellite tags deployed on Indian Ocean billfish during the FLOPPED project
Résumé
The FLOPPED project (2019-2023) aimed to investigate the reproduction zones of five billfish species in the Indian Ocean through a comprehensive data collection initiative, including satellite tagging. Within this project, 111 satellite tags were deployed around the Indian Ocean on blue marlin (Makaira nigricans; n=51), black marlin (Istiompax indica; n=16), striped marlin (Kajikia audax; n=6), swordfish (Xiphias gladius; n=7), sailfish (Istiophorus platypterus; n=30) and a shortbill spearfish (Tetrapturus angustirostris,n=1). Tags were deployed around the Indian Ocean, including around and to the south of Reunion Island, in the waters around Mayotte, Mauritius (Rodrigues), Seychelles, and Australia. Tags were programmed to release from the fish (“pop”) after 3 months and up to 12 months. Two tags are still at sea. The other 109 tags have either popped and reported data (n=88) or have surpassed the programmed time with no data received (n=21). The average duration of tag deployment was about 34% of the programmed time, with a maximum deployment duration of 208 days. Position estimates indicate that most individuals of all species tagged in the south-western Indian Ocean tend to swim to the north-west Indian Ocean off Somalia. Though some individuals tagged in the southwestern basin appeared to have a northeastern trajectory, no observations of mixing between the eastern and western basin were observed. Marlin and sailfish inhabit the top 200 meters during the day and restrict their depth range to the upper 50-100 m at night. Swordfish in the southern Indian Ocean have a much deeper distribution and inhabit the top 600 meters during the day, and restrict their depth range to the top 200 m at night.
Domaines
Sciences de l'environnement| Origine | Fichiers produits par l'(les) auteur(s) |
|---|