Fish Aggregation Dynamics in Tuna Fisheries

Fish aggregation dynamics in tropical tuna fisheries centre on the deployment and monitoring of floating structures that draw pelagic species. These devices exploit natural behavioural tendencies of tunas and associated fauna to congregate beneath floating objects, thereby enhancing detection and capture. Over recent decades, the widespread use of drifting and anchored fish aggregating devices (FADs) has transformed purse‐seine operations, improving fishing efficiency but raising ecological and management challenges. Aggregation processes are governed by a complex interplay of physical oceanography, device design and species‐specific behaviour, leading to variability in colonisation times, species composition and retention. Concurrently, the proliferation of artificial FADs has modified pelagic habitats and altered stock assessments, as aggregated fish may remain in the vicinity of devices longer than under natural conditions. Understanding these dynamics is critical for balancing exploitation with conservation, informing spatial management, biodegradable device design and responsible deployment strategies. Recent advances in satellite tracking, acoustic discrimination and ecological modelling have deepened insights into aggregation patterns, device trajectories, beaching events and by-catch assemblages, underpinning more adaptive fishery management and emerging applications such as conservation FADs within blue-water marine protected areas.

Research from Nature Portfolio

One study has quantified the environmental and operational drivers that lead to the beaching of drifting devices in the Western and Central Pacific. By combining observed beaching records with Lagrangian simulations, researchers have shown that prevailing currents largely determine stranding hotspots, while deployment choices play a secondary role. This work highlights the limited efficacy of simply altering deployment locations and points to integrated measures such as biodegradable materials, at-sea recoveries and targeted removals. A complementary analysis of device trajectories in the Indian and Atlantic Oceans revealed that over 40 percent of drifting aggregating devices ultimately become abandoned, lost or discarded. Tracking buoy data demonstrated key exit points from fishing grounds and proximity to major ports, suggesting that port-based retrieval programmes and targeted recovery in high-exit zones could substantially reduce marine debris and ecological footprints.

Fish Aggregation Dynamics in Tuna Fisheries publication trend

The graph below shows the total number of articles in fish aggregation dynamics in tuna fisheries across all publications each year (not limited to Nature Index journals).

Technical terms

Fish Aggregating Device (FAD): A floating structure deployed to attract and aggregate pelagic fish, enhancing detection and fishing efficiency.

Drifting FAD (dFAD): A FAD left to drift with ocean currents, often equipped with satellite buoys to monitor fish aggregation in open waters.

Anchored FAD: A fixed FAD tethered to the seabed to support localised aggregation of fish near shores.

Beaching: The event of a drifting FAD running aground on coastal areas, with implications for habitat damage and pollution.

Abandoned, Lost or Discarded (ALD) equipment: FADs no longer under active use or retrieval, contributing to marine debris and ecosystem impacts.

References

1. Floating objects in the open ocean: Unveiling modifications of the pelagic habitat induced by forest cover change and climate variations. Global Environmental Change (2024).
2. Fish aggregating devices could enhance the effectiveness of blue water marine protected areas. Conservation Letters (2023).
3. Aggregation process of drifting fish aggregating devices (DFADs) in the Western Indian Ocean: Who arrives first, tuna or non-tuna species?. PLOS ONE (2019).
4. Towards acoustic discrimination of tropical tuna associated with Fish Aggregating Devices. PLOS ONE (2019).
5. Biodiversity and Habitat Characteristics of the Bycatch Assemblages in Fish Aggregating Devices (FADs) and School Sets in the Eastern Pacific Ocean. Frontiers in Marine Science (2017).
6. Environmental versus operational drivers of drifting FAD beaching in the Western and Central Pacific Ocean. Scientific Reports (2019).
7. Recovery at sea of abandoned, lost or discarded drifting fish aggregating devices. Nature Sustainability (2022).
8. Quantifying drifting Fish Aggregating Device use by the world's largest tuna fishery. ICES Journal of Marine Science (2021).