Drifting Fish Aggregating Devices (DFADs) as ecological traps: no evidence displayed by a long-term analysis of yellowfin tuna condition

Amaël Dupaix (1) , Laurent Dagorn (1) , Antoine Duparc (1) , Aurélie Guillou (1) , Jean-Louis Deneubourg (2) , Manuela Capello (1)

1 UMR MARBEC - MARine Biodiversity Exploitation and Conservation - MARBEC
2 ULB - Université libre de Bruxelles

Habitat modifications are one of the major human-induced rapid environmental changes. Drifting Fish Aggregating Devices (DFADs), used by industrial purse seine tropical tuna fisheries, significantly increased the number of floating objects with which tropical tuna associate, raising concerns over the risk of modifying the behavior and altering the biology of these fish (the so-called ecological trap hypothesis). Relying on a time-series of more than 25,000 length-weight samples collected in the western Indian Ocean (1987-2019), we reject the hypothesis that the body condition (Le Cren’s relative condition factor Kn) of yellowfin tuna (Thunnus albacares) decreased concurrently with the increased number of DFADs. This result suggest the absence of negative long-term impacts of DFADs on the biology of tuna. However, as other factors may have counteracted possible negative effects of DFADs, we recommend a long-term monitoring of habitat, biological and behavioral parameters of tunas to detect any critical change.

Mots clés: Indicator log; relative condition factor; Thunnus albacares; Indian Ocean; industrial tuna fisheries; floating objects

Domaines: Biodiversité et Ecologie; Milieux et Changements globaux; Environnement et Société

Amaël Dupaix, Laurent Dagorn, Antoine Duparc, Aurélie Guillou, Jean-Louis Deneubourg, et al.. Drifting Fish Aggregating Devices (DFADs) as ecological traps: no evidence displayed by a long-term analysis of yellowfin tuna condition. 2022. ⟨hal-03690665v2⟩