Abstract
Several species of fish, aggregate around DFADs in marine tropical waters. We captured three predatory species: yellow fin tuna (Thunnus albacares), wahoo (Acanthocybium solandri) and dolphinfish (Coryphaena hippurus) from aggregations under DFADs in the Western Indian Ocean to characterize their diet and determine whether they fed on other DFAD associated organisms. Yellowfin tuna did not feed on DFAD–associated prey, while wahoo and dolphinfish did exploit resources aggregated by the DFADs, though they predominantly fed on other non–associated organisms. Opportunistic feeding on surface swarming stomatopod crustaceans was observed in yellowfin tuna and dolphinfish associated with FADs, but was not observed in wahoo.
Highlights
Floating objects are known to aggregate fishes in tropical oceans
This study describes the diet of three pelagic, predatory species associated with drifting Fish Aggregating Devices (FADs) (DFADs) in the Western Indian Ocean: yellowfin tuna (Thunnus albacares), dolphinfish (Coryphaena hippurus) and wahoo (Acanthocybium solandri), and addresses the ‘concentration of food supply’ hypothesis for DFADs in this environment
Yellowfin tuna did not feed on fishes aggregated under DFADs in the Western Indian Ocean
Summary
Floating objects are known to aggregate fishes in tropical oceans. There has been an increase in the use of DFADs in tropical tuna fisheries in the past two decades, especially in the Western Indian Ocean (Fonteneau et al, 2004), the mechanisms underlying these floating objects are unknown (Fréon & Dagorn, 2000). Many hypotheses have been suggested to explain why these aggregations form, one of which is the ‘concentration of food supply’ hypothesis (Fréon and Dagorn, 2000). This hypothesis states that certain pelagic predators aggregate around FADs to feed upon the fauna of smaller fishes that aggregate under these floating objects (Klima & Wickman, 1971; Fréon & Dagorn, 2000)
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