|Equipment Class: Fishing technology||Equipment Type: Aggregating device|
|Fish Aggregating Device (FAD) is a permanent, semi-permanent or temporary structure or device made from any material and used to lure fish.|
They have been used for thousands of years in various forms. The earliest surface/midwater FADs were elements from nature such as driftwood and trees.
Now surface and midwater artificial FADs are systematically used in a large number of countries. Present practices vary considerably, sometimes involving advanced technology.
Generally speaking, buoys and floats close to the surface comprise the major part of the aggregating system but some models exist with the aggregating device in mid-water - so called midwater FADs – where the only surface component is a small marker buoy (which is less subject to stress from wind and waves and the risk of damage by ships).
The deployment and proliferation of FADs has influenced harvesting practices and become the concern of fisheries managers.
Almost all existing documentation on the use of various types of FADs in different areas indicates that, after a short period, fish are observed around the structure, irrespective of its design.
Traditional FADs, based on long-term fishing experience, are made on-the-spot with local materials and used in shallow coastal waters (depth 50-200 m) by small-scale fishers to catch small pelagic fish and bait, e.g. payaos (Philippines), unjang (Malaysia), rumpon (Indonesia). Modern FADs, the result of imported technology and materials, can be anchored to over 3 000 meters. Certain models have large surface dimensions.
Simple or advanced FADs are left drifting in deep waters to help offshore, artisanal and industrial fleets catch big pelagic fish, mainly tuna. Hundreds of simple, traditional types of drifting FADs are used by each large, modern tuna purse seiner operating in certain areas.
FADs can be used in either a single or multiple arrangement. Common practice is to use more than one with enough distance between each. The most suitable distance between each FAD depends on the abundance and type of species targeted: between several hundred and one thousand metres for small pelagic fish in coastal or shallow waters; or 5 to 10 nautical miles for deep-water tuna FADs.
Some FADs are permanent structures while others are moveable. The former are set mainly in deep waters and relocation is virtually impossible. Present experience shows that the expected life of a permanent FAD would be 2 to 3 years. The mobile, lighter structures can be moved to attract fish to a particular point. Still others can be removed from the water during certain seasons when the fish are not in the area or when the weather is rough, e.g. monsoon.
The profitability of the FAD depends on its lifespan. Of course there can be frequent early losses not always due to vandalism or theft.
For the permanent deepwater FAD, the mooring line and the aggregating device are very costly because of the depth and the necessity for heavier anchor blocks which must be strong enough to resist the forces of wind, waves and currents on the whole structure. They must also be carefully built as, once set, control and maintenance will be limited almost entirely to the upper part not far from the surface. The lighter movable structures require continual maintenance as they are made from natural materials (such as bamboo or palm) which rot in the water.
The life expectancy of a FAD is much greater if proper ocean engineering expertise and related technology are used for the construction of the mooring line (which must be strong and exclude risk of snags and kinks), for the surface buoys and structure (for easy location, day and night, easy avoidance by large vessels, but also to make theft more difficult), possibly, attractors at various levels of the mooring line.
The process of aggregation (to be related to the fouling on the structures, at the surface and on the mooring line of the FAD) is often made in two steps: firstly small fish are attracted and secondly large fish arrive. The bulk of the aggregation can sometimes be at some distance from the FAD.
Using the buoys as a FAD
Courtesy of FAO/FIIT
It is also important to note that, in many cases, the fish aggregation is found not only close to the buoy on the surface but also in deeper water where the species are generally different from those observed near the surface or at a distance from the FAD. In general, larger fish are found in deeper waters. In spite of intensive research the reason fish are attracted to these devices is still not known with certainty. However, the fact is that FADs play the role of offshore banks (moored FAD have to be set far enough from the coast).
It may take around 2-4 weeks for a new FAD to attract big fish. In general, a given FAD can be fished every 10-30 days. As far as operation of fishing gear in relation to the FAD is concerned either the FAD is encircled by the gear or the gear is used at a short distance from it. When the FAD is encircled, different situations can occur:
In shallower waters, setting FADs in conjunction with an artificial reef has proven, in several places, to be a profitable arrangement. When setting FADs offshore the objective is to let fishers catch more fish, which often means encouraging them to go and fish further offshore (in cases, leaving a very coastal overexploited area, lagoon; a FAD provides an exact location, for instance an offshore bank, to head for and a certain guarantee of safety for artisanal craft which can even remain moored to the FAD overnight and fish for several days at a time). FADs may induce the development of a new fishery e.g. for large pelagic resources.
- a light drifting FAD is just towed or lifted out of the net;
- when moored, permanent, FAD are used, the upper part (where most of the fish is aggregated) from the mooring.
Industrial and artisanal fishers often share the same FAD. In some places, not only the commercial sector but also sports fishers benefit from the FADs.
Consideration must be given to the fact that fish behaviour around a FAD differs from one species to another and this determines the different aggregating ability of the FAD for the various species. The FAD may make different species to those generally caught available to the fishers and as a consequence different fishing methods might be needed. Methods used in the open sea may not be suitable for fishing around the FAD.
It has been observed that the use of FADs often alters the exploitation of the resources with more juvenile stocks of fish were being taken when fishing around the FADs.
Legal aspects related to surface/midwater FADS include: ownership of the FAD, ownership of the aggregated fish, adverse effects on other fisheries, resource utilization and management, shipping and navigation. The international standards and guidelines regarding surface/midwater FADs are still very few. So far most FADs are deployed without due regard to any regulations but a number of countries have set up their own, relevant, strict regulations (regulations concerning the number of FADs per owner, position, proper marking, issue of a Government authorization, amount of fishing gear authorized, regular reporting of activities around FAD, etc.).
Any national regulation must take into consideration the provisions of UNCLOS (The United Nations Convention on the Law of the Sea), conventions on navigational safety, shipping routes, conventions on dumping at sea, and decisions by fisheries management bodies.