Fish aggregating devices, or FADs, have reshaped the way the world catches tuna. Built to mimic natural flotsam, these artificial rafts drift through tropical oceans, drawing fish into dense clusters that are then easily captured by industrial purse seine fleets. What began as a clever fishing tool has now become one of the most widespread and contentious technologies in commercial fishing.

Between 2007 and 2021, an estimated 1.4 million of these devices were deployed globally, drifting through more than a third of the world’s oceans, Phys.org reports.

FADs offer clear benefits. By concentrating fish in one place, they reduce the time and fuel required to find and catch tuna. This efficiency lowers costs, increases catches, and reduces the carbon footprint compared to other fishing methods like longlining or pole-and-line fishing, according to Sustainable Fisheries UW. For skipjack tuna in particular—the staple of canned tuna—drifting FADs have become indispensable, with more than a third of global purse seine sets now associated with these devices, as noted in a 2023 study published in Fish and Fisheries.

Drifting fish aggregating devices (FADs) are plastic traps for ocean life.

The ecological trade-offs

But this convenience carries steep ecological consequences. The biggest concern is bycatch—non-target marine species like sharks, turtles, and juvenile tuna that are swept up with the rest. While bycatch is a concern in nearly all fishing methods, FAD-associated purse seine sets see significantly higher levels than sets on free-swimming tuna schools, Galapagos Conservation Trust reports. Shark mortality, in particular, is alarmingly high—reaching 84% in some FAD fisheries, according to the Fish and Fisheries study.

Juvenile tuna also face heightened risk. FADs tend to attract younger, smaller fish—especially yellowfin and bigeye—that haven’t had a chance to reproduce. This undermines the goal of sustainable harvests and can drive stock declines over time, researchers report. And because many fishers target the same tuna species using different gear, this practice sparks economic tension between fleets using FADs and those relying on traditional methods.

Most drifting FADs are lost or abandoned, polluting the sea.

Ghost gear and habitat destruction

Once abandoned, FADs become ocean waste. Made largely from plastic, nets, ropes, and even electronic echosounder buoys, they drift aimlessly—often for years. An estimated 10% or fewer are ever retrieved, says Galapagos Conservation Trust. They entangle marine life, damage coral reefs, and pollute remote coastlines. Some FADs have been found thousands of miles from their point of origin, washing ashore in over 100 countries, Phys.org reports.

These rafts may also alter fish behavior. Some scientists worry FADs act as “ecological traps,” luring fish into nutrient-poor or dangerous areas under the false signal of shelter or food. There’s evidence that tuna associated with FADs have emptier stomachs and lower fat reserves than those found in the wild, according to Fish and Fisheries.

The climate change curveball

Layered on top of all this is the looming challenge of climate change. A study published in ScienceDirect predicts a 36% decline in global tuna productivity by 2050, with body sizes shrinking by as much as 15%. This means that while FADs may currently help optimize harvests, the very fish they’re designed to catch will be less plentiful and smaller in the decades ahead. That raises serious concerns about the long-term viability of FAD-dependent fisheries and their economic return.

Bycatch from FADs includes threatened and endangered species.

To ban or to manage?

Some have called for an outright ban on drifting FADs. Advocates point to their bycatch rates, marine pollution, and role in juvenile overfishing. But experts warn that banning FADs could cause unintended harm. Skipjack tuna, which dominate FAD catches, are still managed sustainably in most regions, according to stock assessments referenced in Fish and Fisheries. A ban would likely shift pressure to other species or force fishers to use less efficient, higher-emission methods, raising seafood prices and reducing supply—especially for low-income populations that rely on tuna for protein, notes Sustainable Fisheries UW.

The better answer may lie in smarter regulation. Scientists and fishers have already collaborated on low-entanglement and biodegradable FAD designs. Regional fisheries management organizations are now piloting FAD registries, deployment limits, spatial closures, and recovery programs. Yet progress remains slow, hindered by political gridlock, inconsistent enforcement, and a lack of transparency in FAD tracking data, as Galapagos Conservation Trust reports.

Plastic components from FADs enter the marine food chain.

The way forward

Despite their problems, FADs are unlikely to disappear. The key question is whether we can make their use sustainable. Solutions exist—many developed in partnership with the fishing industry itself. But they require buy-in from regulators, fleets, and consumers alike. As climate change squeezes marine productivity, and as the environmental costs of industrial fishing rise, we’ll need tools that balance economic efficiency with ecological responsibility.

The ocean is vast, but not limitless. Managing the global footprint of FADs—rather than ignoring it—may be our best hope for protecting the species they target, the ecosystems they affect, and the people who rely on both.

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