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Purse seine fishers extensively deploy drifting Fish Aggregating Devices (FADs) to aggregate and catch
tropical tuna, with 46,000 to 65,000 FADs deployed in the Pacific Ocean annually, and 16,000–25,000
FADs in the eastern Pacific Ocean (EPO) only. Main concerns related to the loss and abandonment of
FADs are i) marine pollution; ii) the potential risk of entanglement of sea turtles and other marine
fauna in FAD netting while drifting at sea or when stranded; and iii) the potential to cause ecological
damage to vulnerable ecosystems via stranding events, including reefs, beaches, and other essential
habitats for sea turtles. To explore and quantify the potential connectivity between FADs and
important oceanic or coastal sea turtles habitats in the Pacific Ocean, a series of passive-drift
Lagrangian simulation experiments were undertaken based on possible FAD drifting behaviour.
Corridors of connectivity between industrial FAD fishing grounds and zones of important habitats for
sea turtles were identified. For FADs deployed in the EPO, the main areas of concern appear to be the
turtle habitats in the south-eastern Pacific Ocean, corresponding to oceanic leatherback turtle
(Dermochelys coriacea) migration and feeding grounds. Moderate accumulation of FADs was also
detected in the equator, coastal and oceanic habitats and nesting sites around Mexico, Costa Rica and
Panama. Finally, a large equatorial area, south of Hawaiʻi, important leatherback turtle foraging
habitat, exhibited large numbers of FADs transiting when deployed in the equatorial zones north of
the equator, from both the EPO and WCPO. It should be noted that the connectivity patterns detected
appear to be somewhat mitigated against by the current deployment distribution of FADs in the EPO.
Additional research and analyses should be performed i) to better understand at-sea interactions
between FADs and sea turtle populations and potential entanglements; and ii) to quantify the likely
changes in connectivity and distribution of FADs within the equatorial fishing grounds and higher
latitude sea turtle habitats, under proposed non-entangling and Biodegradable FAD measures or
changes in FAD deployment strategies.
