2. Longlines

    The major types of long line are bottom set longlines and drift-longlines. According to the target species the construction of the longline is different, such differences are the length of the mainline, branch lines, hook sizes, numbers of hooks, etc. Some of the major longlines are as follows:

2.1. Tuna Longline

    The tuna longline is operated in offshore areas and it is the most common gear for fishermen in the Central Provinces of Vietnam. Fishing boats of 33 to 350 Hp use the tuna longline. The length of the longline varies between 18 to 25 km. The main species are bigeye tuna and yellowfin tuna. Flying fish, mackerel are used as bait. Bait are caught or are bought from fish markets or other fishing boats. Flying fish gill nets are part of the equipment in all longline boats.

Line Setting:

    When on the fishing grounds, the skipper identifies the current and wind directions and chooses the most suitable direction for setting (the setting direction is usually at right angles to the current). The hooks are baited while the branch lines are tied to the mainline and the mainline is set. Normally, during the setting, the vessel runs at a speed of 4 - 6 kts allowing the line to drift on the current flow.

Line Hauling:

    When hauling the mainline, the vessel runs along the mainline at a speed of 2.5 - 3.5 kts, the branch lines are collected separately after the ties between them are undone.

    The average catch on a fishing trip, which takes 15-30 days, is 1.2-4.3 tons of big eye tune and yellow fin tuna.

2.2. Shark Longline

     The development of the shark longline has developed in the provinces of the Central region. At present, the level of catch is low and the number of shark longline boats small. The shark longline is operated by fishing boats of 60 to 90 Hp and in offshore waters. The length of mainline can be as much as 24-32 km with 620 to 1,300 hooks.

The method of setting is similar to that of the yellow fin tuna longline. However, the ties between the branch line and the mainline are fixed.

     The shark long-liner runs in the direction of the line with a speed suitable to the conditions of the waves, wind and fishing ground. The hooks, branch lines and mainline are put stored in the hook-buckets or on hangers.

     The catch of the average trip (lasting from 20 to 30 days) can be 4 to 4.2 tons.

2.3. Bottom Longline

     The bottom longline is used to catch demersal species like grouper, snapper, conger, etc. Conger is one of the most important species for bottom longlining in the Southern region. The catch of conger is about 90% of the total catch of bottom longline in this region. The components of a longline consist mainly of float lines, mainline, branch lines, sinkers and hooks. The longline is made of Nylon monofilament. The hook size depends on the target species. Boats used for bottom longlines have engines of 20-350 Hp and operate in fishing grounds having a depth of less than 100 m. The length of the bottom longline is 2-30 km with 900-2000 hooks.

     The bottom long-liner runs at a speed of 3 - 5 kts at right angles in the direction of the current or according to characteristics of the sea bottom. Hooks are removed from the hangers and are baited one hook after another before being set.

     The vessel can move along the longline following the floating flagpoles, with the recovery speed is 2 - 4 kts according to the wave and wind conditions and the quantity of hooked fish.

     An average catch of a 30 km longline per fishing trip (8 days) is from 2 to 5 tons.