Lower entanglement risk fish aggregating devices
Fish aggregating devices where only small mesh netting is used (< 7 cm stretched mesh) and rafts are tightly wrapped with small mesh netting. The underwater structure is tightly tied into bundles (called “sausages”) so that the risk of entanglement for non‑target species is much lower.
Highest entanglement risk fish aggregating devices
Fish aggregating devices that are constructed with any netting materials, including old large‑mesh purse seine netting, used to cover rafts or suspended beneath in open panels. These FADs are known to cause the highest rate of entanglements with turtles and sharks.
Fish aggregating devices
Man‑made floating objects specifically designed to encourage fish aggregation at the device. They can be anchored to the ocean floor (anchored FADs) or set to drift in the open ocean (drifting FADs).
FADs are widely used as a fishing method due to its high efficiency, although they have been associated with several negative ecosystem impacts, such as bycatch and overfishing. Today, they support a large number of fishing vessels, especially purse seine fleets targeting tropical tunas in open oceans, but also artisanal pole‑and‑line vessels in shallow nearshore waters.
The deployment and use of FADs allows skippers to fish in remote areas where tuna schools were not very abundant or easily accessible before, to plan trips with greater certainty and efficiency, to make fewer “skunk sets” (sets where the school of tuna escapes) and to catch more skipjack tuna (a very productive and abundant tuna). FADs are equipped with some type of location device, ranging from simple radio beacons to sophisticated GPS, enabling the skipper or fleet manager to locate them remotely. The number of FADs deployed by a vessel or company increases their capacity because of increased options for “cherry picking” the FADs with more biomass underneath. But, there may come a point where high FAD density in an area is counter‑productive because of a saturation effect that reduces aggregation size.
See also HERFADs, LERFADs, NEFADs, BFADs, Bio-FADs, Jelly-FADs.
FAD strategy
Vessels that largely rely on FADs (floating objects) to catch tunas, primarily skipjack.
See also SKJ.
Drifting fish aggregating devices
Fish aggregating devices not tethered to the bottom of the ocean. A DFAD typically has a floating structure (such as a bamboo or metal raft with buoyancy provided by buoys, corks, etc.) and a submerged structure (made of old netting, canvass, ropes, etc.). Its use has rapidly expanded in all the oceans. The most sophisticated DFADs include sonar and GPS capabilities so that the FAD can be geolocated and the fish population under the FAD estimated.
Anchored fish aggregating devices
They usually consist of a very large buoy, anchored to the bottom of the ocean with a chain. AFADs are called ‘payaos’ in some regions.
