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A fish aggregating (or aggregation) device (FAD) is a man-made object used to attract
ocean The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the wor ...
-going
pelagic fish Pelagic fish live in the pelagic zone of ocean or lake waters—being neither close to the bottom nor near the shore—in contrast with demersal fish that do live on or near the bottom, and reef fish that are associated with coral reef ...
such as
marlin Marlins are fish from the family Istiophoridae, which includes about 10 species. A marlin has an elongated body, a spear-like snout or bill, and a long, rigid dorsal fin which extends forward to form a crest. Its common name is thought to deriv ...
,
tuna A tuna is a saltwater fish that belongs to the tribe Thunnini, a subgrouping of the Scombridae (mackerel) family. The Thunnini comprise 15 species across five genera, the sizes of which vary greatly, ranging from the bullet tuna (max length: ...
and
mahi-mahi The mahi-mahi () or common dolphinfish (''Coryphaena hippurus'') is a surface-dwelling ray-finned fish found in off-shore temperate, tropical, and subtropical waters worldwide. Also widely called dorado (not to be confused with ''Salminus brasil ...
(dolphin fish). They usually consist of
buoy A buoy () is a floating device that can have many purposes. It can be anchored (stationary) or allowed to drift with ocean currents. Types Navigational buoys * Race course marker buoys are used for buoy racing, the most prevalent form of yac ...
s or floats tethered to the ocean floor with concrete blocks. FADs attract fish for numerous reasons that vary by species. Fish tend to move around FADs in varying orbits, rather than remaining stationary below the buoys. Both recreational and commercial
fisheries Fishery can mean either the enterprise of raising or harvesting fish and other aquatic life; or more commonly, the site where such enterprise takes place ( a.k.a. fishing ground). Commercial fisheries include wild fisheries and fish farms, bot ...
use FADs. Before FADs, commercial tuna fishing used purse seining to target surface-visible aggregations of birds and dolphins, which were a reliable signal of the presence of tuna schools below. The demand for dolphin-safe tuna was a driving force for FADs.Armstrong WA and Oliver CW (1996
Recent use of fish aggregation devices in the eastern tropical Pacific tuna purse-seine fishery: 1990-1994
Administrative report LJ-96-02, Southwest Fisheries Science Center,
NOAA The National Oceanic and Atmospheric Administration (abbreviated as NOAA ) is an United States scientific and regulatory agency within the United States Department of Commerce that forecasts weather, monitors oceanic and atmospheric conditio ...
.
In the past, people in the Pacific islands used bamboo rafts to make it easier to catch tuna that gathered below. Today, the FAD has made fishing much easier for them.


Fish behaviour

Fish are fascinated with floating objects. They use them to mark locations for mating activities. They aggregate in considerable numbers around objects such as drifting flotsam, rafts, jellyfish and floating seaweed. The objects appear to provide a "visual stimulus in an optical void", and offer refuge for juvenile fish from predators. The gathering of juvenile fish, in turn, attracts larger predator fish. A study using sonar in French Polynesia, found large shoals of juvenile
bigeye tuna The bigeye tuna (''Thunnus obesus'') is a species of true tuna of the genus ''Thunnus'', belonging to the wider mackerel family Scombridae. In Hawaiian, it is one of two species known as ahi, the other being the yellowfin tuna. Bigeye tuna are f ...
and
yellowfin tuna The yellowfin tuna (''Thunnus albacares'') is a species of tuna found in pelagic waters of tropical and subtropical oceans worldwide. Yellowfin is often marketed as ahi, from the Hawaiian , a name also used there for the closely related bigeye ...
aggregated closest to the devices, 10 to 50m. Further out, 50 to 150m, was a less dense group of larger yellowfin and albacore tuna. Yet further out, to 500m, was a dispersed group of various large adult tuna. The distribution and density of these groups was variable and overlapped. The FADs were also used by other fish, and the aggregations dispersed when it was dark.


Types

Drifting FADs are not tethered to the bottom and can be man made, or natural objects such as logs or driftwood. Moored FADs occupy a fixed location and attach to the sea bottom using a weight such as a concrete block. A rope made of floating synthetics such as polypropylene attaches to the mooring and in turn attaches to a buoy. The buoy can float at the surface (lasting 3–4 years) or lie subsurface to avoid detection and surface hazards such as weather and ship traffic. Subsurface FADs last longer (5–6 years) due to less wear and tear, but can be harder to locate. In some cases the upper section of rope is made from heavier-than-water metal chain so that if the buoy detaches from the rope, the rope sinks and thereby avoids damage to passing ships who no longer use the buoy to avoid getting tangled in the rope. ''Smart'' FADs include sonar and GPS capabilities so that the operator can remotely contact it via
satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisotop ...
to determine the population under the FAD.


Scope

Drifting FADs are widespread in the Atlantic,
Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...
and Indian ocean
purse seine Seine fishing (or seine-haul fishing; ) is a method of fishing that employs a surrounding net, called a seine, that hangs vertically in the water with its bottom edge held down by weights and its top edge buoyed by floats. Seine nets can be de ...
fisheries. They catch over 1 million tons of tuna (nearly one-third of the global tuna total) and over 100,000 tons of by-catch in the vicinity of FADs as of 2005. Skipjack ''Katsuwonus pelamis'',
bigeye tuna The bigeye tuna (''Thunnus obesus'') is a species of true tuna of the genus ''Thunnus'', belonging to the wider mackerel family Scombridae. In Hawaiian, it is one of two species known as ahi, the other being the yellowfin tuna. Bigeye tuna are f ...
''Thunnus obesus'' and yellowfin ''Thunnus albacares'' tuna are the three primary tropical tuna species that FADs target. Other fish include
albacore The albacore (''Thunnus alalunga''), known also as the longfin tuna, is a species of tuna of the order Perciformes. It is found in temperate and tropical waters across the globe in the epipelagic and mesopelagic zones. There are six distinct st ...
, dolphin fish,
wahoo Wahoo (''Acanthocybium solandri'') is a scombrid fish found worldwide in tropical and subtropical seas. It is best known to sports fishermen, as its speed and high-quality flesh makes it a prized and valued game fish. In Hawaii, the wahoo is kno ...
, blue marlin,
striped marlin The striped marlin (''Kajikia audax'') is a species of marlin found in tropical to temperate Indo-Pacific oceans not far from the surface. It is a desirable commercial and game fish. The striped marlin is a predator that hunts during the day in t ...
,
mako shark ''Isurus'' is a genus of mackerel sharks in the family Lamnidae, commonly known as the mako sharks. Description The two living species are the common shortfin mako shark (''I. oxyrinchus'') and the rare longfin mako shark (''I. paucus''). The ...
,
silky shark The silky shark (''Carcharhinus falciformis''), also known by numerous names such as blackspot shark, gray whaler shark, olive shark, ridgeback shark, sickle shark, sickle-shaped shark and sickle silk shark, is a species of requiem shark, in the ...
, whitetip shark,
galapagos shark The Galapagos shark (''Carcharhinus galapagensis'') is a species of requiem shark, in the family Carcharhinidae, found worldwide. It favors clear reef environments around oceanic islands, where it is often the most abundant shark species. A lar ...
, mackerel, and
bonito Bonitos are a tribe of medium-sized, ray-finned predatory fish in the family Scombridae – a family it shares with the mackerel, tuna, and Spanish mackerel tribes, and also the butterfly kingfish. Also called the tribe Sardini, it consists of ...
. Before FADs, pelagic purse seiners targeted free-swimming schools of tuna. Increasing FAD use over the past 30 years has increased the productivity of the
fishing fleet A fishing fleet is an aggregate of commercial fishing vessels. The term may be used of all vessels operating out of a particular port, all vessels engaged in a particular type of fishing (as in the "tuna fishing fleet"), or all fishing vessels of ...
, but has significant side-effects. The average FAD-caught fish is smaller and comes with relatively large
bycatch Bycatch (or by-catch), in the fishing industry, is a fish or other marine species that is caught unintentionally while fishing for specific species or sizes of wildlife. Bycatch is either the wrong species, the wrong sex, or is undersized or juve ...
raising concern about declining populations of several species of pelagic sharks. The U.S. state of
Hawaii Hawaii ( ; haw, Hawaii or ) is a U.S. state, state in the Western United States, Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is ...
operates 55 surface FADs around its islands to support sport fishing and marine research.


See also

*
Artificial reef An artificial reef is a human-created underwater structure, typically built to promote marine life in areas with a generally featureless bottom, to control erosion, block ship passage, block the use of trawling nets, or improve surfing. Many re ...
* Biorock *
Marine debris Marine debris, also known as marine litter, is human-created waste that has deliberately or accidentally been released in a sea or ocean. Floating oceanic debris tends to accumulate at the center of gyres and on coastlines, frequently washin ...
*
Multi-purpose reef A multi-purpose reef, also commonly known as an artificial surfing reef or surf reef, is a structure located offshore designed to induce wave breaking in a manner that creates a wave suitable for surfing or body boarding. Artificial surfing reefs ...


References


External links


FADs in Hawaii, USA

FADs in New South Wales, Australia


* Bhavani, V (2004

FAO The Food and Agriculture Organization of the United Nations (FAO)french: link=no, Organisation des Nations unies pour l'alimentation et l'agriculture; it, Organizzazione delle Nazioni Unite per l'Alimentazione e l'Agricoltura is an intern ...
: Information document: BOBP/INF/2, Rome. {{fisheries and fishing Fishing equipment