There are two major types of longline, namely; the bottom set longline and the tuna longline. The bottom set longline is the most common for small-scale fishermen as it is used to catch sparsely distributed demersal species. It is set in shallow muddy-sandy bottom to catch hairtail, grouper, snapper, shark and nemipterids. The components of a longline consist mainly of floatline, mainline and branchlines. The branchlines consist of the mainline proper, swivel, wire leader and hook. The set longline is made of nylon monofilament. The twine and hook sizes depend on the target species. Usually, there are 200 to 1,000 hooks per set. Sliced fish is the common biat. Prior to setting, the hooks are baited and arranged in the hook rach. Sometimes, sand is placed in the box to prevent the lines from entangling. Operations maybe done early in the morning or before sundown. During setting, weights are tied along the mainline at intervals of 100 hooks or more to let the line lie on the sea bottom. A specific kind of catch is the spiny dogtooth shark which are available in some specific fishing grounds. Its oil has many uses. An improvised line hauler is utilized by the fishermen during hauling.
The original tuna longline is made of hard-laid nylon multifilament mainline with a combination of polyester rope hard laid and monofilament nylon in the branchlines. Nowadays, the mainline and branchline are made of PA monofilament. The branchlines consists of the branchline proper, secondary branchline, swivel, wire leader and the hook. A flagpole with float, or a radio buoy are accessories used during fishing operations.
The tuna longline is operated by commercial fishing boats of 30 to 50 GT using Taiwanese-technology. The unit is divided into baskets or containers. The length reaches 20 to 30 miles long when set. Development in tuna longling is also very fast. Targeting bigger tuna especially the big-eyed tuna which inhabit the deeper water makes the fishermen increase the depth of the floatline and the branchline. Originally, the length of the floatline is 15 m. and the branchline is 20 m. Nowadays, the floatling length is increased to 30 m. and the branchlines from 40 to 50 m. deep. Caught tunas are immediately stocked in the fish hold. In some companies, tunas are gutted, gilled and wased with sea water to remove blood and slime.
Live milkfish or frozen squid are used as baits. The shiny and moving fish bait attracts the tuna, hence, the catch rate has increased effectively. With still wide area of the Exclusive Economic Zones not exploited by commercial fishermen, tuna longline might be the method to increase production and exports.