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The FLOPPED project aims to investigate the reproduction zones of five billfish species in the Indian Ocean through a comprehensive data collection initiative, including satellite tagging data and biological sampling. Within the framework of this project, 100 satellite tags are to be deployed around the Indian Ocean, on blue marlin (Makaira nigricans), black marlin (Makaira indica), striped marlin (Tetrapturus audax), swordfish (Xiphias gladius), and sailfish (Istiophorus platypterus). Tagging and biological sampling were originally focused on six study sites, including Reunion, Mayotte, Mauritius (Rodrigues), Seychelles, Sri Lanka and Indonesia. However, due to logistical complications resulting from the global COVID-19 pandemic, we search for participants from a broader range of sites among our WPDCS colleagues to maximise the coverage and representativeness of this dataset. Here, we present on the first results of the 48 tags that have been deployed since the start of the project. Of these, 34 tags were deployed via a network of sports fishers using pole and line that were trained to tag by IFREMER and COOOL personnel in Reunion Island, Rodrigues, Seychelles and Mayotte. These tags were deployed on 23 blue marlin, 5 black marlin, 12 sailfish, 1 shortbill spearfish (Tetrapturus angustirostris). An additional 7 tags were deployed via an experiment whereby tags were deployed by a fisheries observer aboard a Portuguese longliner targeting swordfish and operating in the Indian Ocean south of Reunion Island. Swordfish were caught on the longline and tagged at haul-back if they were alive and considered to be in good condition. Tags were programmed to release from the fish (“pop”) after 3 or 6 months. One of the 48 tags that were deployed is still attached to the fish, 3 tags popped after < 1 week due to a problem with the anchoring system, 3 tags popped after < 1 day, likely due to mortality and did not have sufficient data to calculate trajectories, 8 tags never transmitted a signal, and trajectories were estimated from 26 tags. The average duration of tag deployment was about 55% of the programmed time. Position estimates indicate that fish tagged in the south-western Indian Ocean tend to swim to the north-west Indian Ocean off Somalia. Some marlin appeared to have a northeastern trajectory, and one swam directly from Reunion to the southern tip of Madagascar. Marlin and sailfish appear to inhabit the top 200 meters during the day and restrict their depth range to the upper 50-100 m at night. In contrast, swordfish in the southern Indian Ocean appear to inhabit the top 600 meters during the day, and restrict their depth range to the top 200 m at night. While we were able to obtain some data from the longline swordfish tagging experiment, the tagged fish experienced a high rate of mortality, likely due to extended time on the line. We note that our tagging protocol is a living document and is improved after evaluation of each event. We use our increasing experience to train a network of sports fishers, and we encourage any IOTC colleagues interested in participating to contact our team.
