Canadian researchers have discovered that fish aggregating devices (FADs) used in tuna fishing are causing environmental harm by colliding with coral reefs, even within marine protected areas. Despite fishing bans in these zones, drifting FADs have infiltrated over 1,500, or half, of the world’s marine protected areas, as per a recent study published in Science Advances.
Understanding FADs and Their Role in Tuna Fishing
Drifting FADs are instrumental in catching smaller tropical tuna, particularly skipjack, which is commonly canned.
These floating rafts, roughly the size of a boardroom table, are constructed using wood or bamboo with plastic components, explained Boris Worm, a marine conservation professor at Dalhousie University. In the past, mesh nets were suspended beneath them to attract fish, but due to wildlife entanglement concerns, these nets were globally banned in 2025 and replaced with ropes.
FADs attract small fish seeking shelter similar to driftwood, which, in turn, draws predator schools like tuna, making them easier to catch using a fishing boat.
Equipped with a plastic GPS buoy and fish detector, FADs enable fishing boats to return and fish near them using a purse seine net once a sufficient number of fish have congregated beneath.
Approximately 100,000 FADs are released into the ocean annually, with around 90% eventually lost, highlighting their disposable nature, according to Worm.
While FADs are typically operational for a year, they can continue drifting for up to five years, often ending up stranded or entangled during that period.
Environmental Impacts within Protected Areas
Entrance of FADs into marine protected areas results in beach strandings and coral reef damage, contributing to plastic pollution, stated Laurenne Schiller, lead author of the recent study and a postdoctoral researcher at Dalhousie University.
The study recorded over 6,000 FAD strandings in 174 protected areas, with reports of these rafts causing significant coral destruction.
These FADs have been known to entangle sharks and turtles, although the ban on netting aims to mitigate such incidents. However, older FADs with netting are still present in the ocean.
