The technology used in harvesting of tuna resources is adjusted to the characteristic and behavior of the fish target. Tuna fish is the fast-swimming pelagic fish that can be found in large shoals. Therefore, the fishing gear used must be in accordance with the behavior of the fish. There are five types of tuna fishing gear i.e. tuna long line, huhate (pole and line), hand line, purse seine, and gill nets.
Tuna long line is the most effective fishing gear for harvesting tuna. It consists of mainline with branch lines with hooks attached. One tuna long line operated 1.000 – 2.000 hooks in one setting. Generally, tuna long line operated in high seas or near the ocean area. Tuna long line is a passive fishing gear that waiting for the bait be eaten by fish target. Once the hooks are set in the water, the vessel engines will be shut down so the vessel and the fishing gear will drift with the ocean current. Drifting will last for estimated 4 hours, and then the vessel crew will haul the main line into the vessel. The long line bait has to be attractive i.e. fish with shiny scales, can survive in the water, and has strong bones. The bait that used in long line fisheries works as fish lure. Basically, the fishermen will use small pelagic fish as bait fish such as Sardinella (Sardinella sp.), scad (Decapterus sp.), mackerel ( Rastrelliger sp.) and milk fish (Chanos chanos).
Huhate or pole and line is a tool consist of a hooked line attached to a pole. Pole and line is used to catch fish especially skipjack tuna. No wonder if this fishing gear is often called “skipjack fishing rod”. Huhate can be operated throughout the day when there are schooling fish around the vessel. Pole and line is an active fishing gear. There is unique aspect from this fishing gear, the hooks will be covered with chicken feather or dummy feather made from plastic in order not to be seen by fish.
The pole and line vessel have a special construction, the vessel’s bow is longer than other fishing vessel because that area will occupied by fish anglers. Generally, pole and line vessel is smaller than other fishing vessels. This vessel have sprayer to make water splash and fish hold to gather the live bait. The fishing process is carried out together by all fish anglers. They will sit at the bow based on their competence. The first team is the excellent angler who can lift the fish 50 – 60 fish per minute. The first team will sit in the bow. The second team will sit at the left or right vessel hull. The third team or the beginner angler will sit at the stern. The anglers need to pay attention to it so there is no fish that fall back into the water, because it will cause the schooling fish move away.
Pole and line fishing use the live bait to attract skipjack fish swim closer to the surface. The water will be sprayed from the back of the fishing vessel and bait fish are scattered onto the surface of the water, creating the illusion of an active school of prey fish. Pole and line vessel usually use anchovy as live fish bait (Stolephorus spp.).
Hand line can be operated during the day. The construction of the hand line is very simple. There are 2 – 10 hooks in one main line. The hand line operation usually associate with FADs (Fish Aggregating Devices), it helps to collect the tuna fish in small area. During the fishing activities, one FAD will be surrounded by 5 hand line vessels, each vessel contains 3 – 5 fishermen. They use fresh fish as bait. The main target of hand line operation is tuna fish (Thunuss spp.)
Purse seine is a kind of net in which have number of rings or iron bracelets are attached at the bottom. Currently, there are not too many tuna catches using purse seine, even if there are only small-scale tuna catches. Purse seine operated by surround the schools of fish. The loop is done quickly, and then quickly pulls the purse line between the existing rings, so that the net will form like a bowl. High speed is needed so that the fish cannot escape. After the fish are in the net bowl, then the catch is taken using a scoop. Purse seine can be operated day or night. Operations during the day often use FADs or payaos. The purse seine vessel usually use lamp during the night operation to attract and collect the fish. Payaos or FADs also can be used for prevent tuna migration so that the fish will stay around the payaos longer (Gafa et al., 1987). Uktolseja (1987) stated that payaos can keep skipjack tuna stay longer at the FAD area for 340 days. Gill net is rectangular net that have similar mesh size. It named gill net because it works by trapping the fish gill. The size of the fish caught is relatively in the same size.
Gill net is a passive fishing gear. It will placed into the water, the vessel and the fishing gear will drifting with the flow for 2 -3 hours. After several hours, the fishermen will lift the gill net to collect fish caught into the fish hold.