Океан балығын тартуға арналған жасанды құрылғылар

Man made object used to attract ocean going pelagic fish
A fish aggregating (or aggregation) device (FAD) is a man made object used to attract pelagic fish such as marlin, tuna and mahi mahi (dolphin fish). They usually consist of buoys or floats tethered to the ocean floor. Various types of FADs have been employed in the traditional fishing cultures of Island Southeast Asia (especially in the Philippines), Japan, and Malta for centuries. Modern FADs are increasingly being used in modern commercial and sport fishing. and offer refuge for juvenile fish from predators. The juvenile fish, in turn attract predators. A study using sonar in French Polynesia, found large shoals of juvenile bigeye tuna and yellowfin tuna aggregated closest to the devices, at distances of 10 to 50m. Further out, 50 to 150m, a less dense group of larger yellowfin and albacore tuna gathered. Yet further out, to 500m, was a dispersed group of mature tuna. The distribution and density of these groups was variable and overlapped. The FADs were also used by other fish, and the aggregations dispersed after dark.

Drifting FADs float with the currents, are not tethered to the bottom and can be man made, or natural objects such as logs or driftwood. They can include sonar and GPS capabilities so that operators can contact it via satellite to assess associated populations. 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 for fishers to locate. In some cases the upper section of rope is made from metal chain so that if the buoy detaches from the rope, the rope sinks and thereby avoids damage to passing ships.

Fish aggregating devices have been traditionally used for centuries by fishermen in Island Southeast Asia, Japan, and Malta. In Indonesia, Malaysia, Timor Leste, and among the Moken people of Myanmar, a very similar traditional method is known as rumpon or roempon in Malay. It uses an anchored bamboo raft supporting a lure line with palm leaves or bundles of grass attached along its length. Fish attracted to the rumpon are caught using dip nets or encircling nets. In modern times, kannizzati rafts are often made from polystyrene with attached palm fronds harvested from introduced Canary Island date palms (Phoenix canariensis).

Drifting FADs are widespread in the Atlantic, Pacific and Indian Ocean purse seine fisheries. They attract over 1 million tons of tuna (nearly one third of the global tuna total) and over 100,000 tons of by catch as of 2005. Skipjack (Katsuwonus pelamis), bigeye tuna (Thunnus obesus) and yellowfin (Thunnus albacares) tuna are the three primary tuna species that FADs target. Other targets include albacore, dolphin fish, wahoo, blue marlin, striped marlin, mako shark, silky shark, whitetip shark, galapagos shark, mackerel, and bonito. Both recreational and commercial fisheries use FADs. Increasing FAD since 1990 increased the productivity of the fishing fleet, but has significant side effects. The average FAD caught fish is smaller and comes with relatively large bycatch, raising concern about populations of pelagic sharks. The U. S. state of Hawaii operates 55 surface FADs around its islands to support sport fishing and marine research.