Tuna aggregation dynamics at Drifting Fish Aggregating Devices: a view through the eyes of commercial echosounder buoys

Type Article
Date 2020-12
Language English
Author(s) Baidai Yannick1, 2, Dagorn Laurent1, Amandè Monin J2, Gaertner Daniel1, Capello Manuela1, Proud Roland
Affiliation(s) 1 : MARBEC, Univ Montpellier, CNRS, Ifremer, IRD, Sète, France
2 : Centre de Recherches Océanologiques (CRO), 29 rue des pêcheurs, BPV 18, Abidjan, Côte d’Ivoire
Source Ices Journal Of Marine Science (1054-3139) (Oxford University Press (OUP)), 2020-12 , Vol. 77 , N. 7-8 , P. 2960-2970
DOI 10.1093/icesjms/fsaa178
WOS© Times Cited 1
Keyword(s) absence times, associative behaviour, colonization times, Drifting Fish Aggregating Devices (DFADs), echosounder buoys, residence times, tropical tunas
Abstract

This study addresses novel questions on the dynamics of tuna aggregations around floating objects, using echosounder buoys data collected throughout the drifts of newly deployed Drifting Fish Aggregating Devices (DFADs) in the Atlantic Ocean (AO) and Indian Ocean (IO). Time series of presence/absence of tunas were obtained by supervised classification of acoustic data. To avoid biases related to the variability in individual DFAD soak times, a new approach was developed to estimate the average colonization time of new DFADs by tuna aggregations. We showed that tunas colonize DFADs after an average of 16 days in the AO, and 40 days in the IO. Moreover, the analysis indicated that the time span during which tuna aggregations occupy DFADs is driven by a time-independent process with short- and long-term residence modes. On average, DFADs were continuously occupied by tuna aggregations for 6 and 9 days in the IO and AO, respectively. The time between two consecutive aggregations at the same DFAD averaged 9 days in the IO and 5 days in the AO. Throughout their soak time after being colonized, DFADs remained occupied for a larger proportion of time in the AO (63%) than in the IO (45%).

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Baidai Yannick, Dagorn Laurent, Amandè Monin J, Gaertner Daniel, Capello Manuela, Proud Roland (2020). Tuna aggregation dynamics at Drifting Fish Aggregating Devices: a view through the eyes of commercial echosounder buoys. Ices Journal Of Marine Science, 77(7-8), 2960-2970. Publisher's official version : https://doi.org/10.1093/icesjms/fsaa178 , Open Access version : https://archimer.ifremer.fr/doc/00659/77063/