Tuna Fish

Tuna is a high sea fish occurring in shoals in the tropical and temperate seas. World tuna landings in 1968 amounted to 1.4 million tonnes. Intensive fishing of tuna place in the Pacific and Indian Oceans. Japan, U.S.A., Spain and Peru constitute the leading producers of tuna and have maintained this position over the last decade. Of late, Korea and China (Taiwan) have emerged as important producers. They represent about 2.5 % of the world trade in fishery commodities.

Tuna and related fish species is a major constituent of the Pelagic-Ocean Fisheries in the tropical and sub tropical seas around the world. Some of the species as the albacore, bigeye, bluefin, skipjack and yellowfin are widely distributed over a great part of the world oceans and support fisheries of considerable importance being exploited by some of the Maritimes nations.

Presently four principal species of tuna-yellowfin, skipjack, albacore and bluefin are popular in the world markets, the first being the most dominant species. Of these, only the first three namely, yellowfin, skipjack and albacore are available in Indian Ocean, the first two around 10⁰S latitude and the late south of this area.

Landings

The world tuna catch in the five-year period of 1964 to 1968 has ranged from 1.200-1,400 thousand tonnes. As against this, India’s catch of tunas ranged between 3.063 and 5.002 thousand tonnes during the period. During 1989, landing of tuna rose to 36.4 thousand tonnes. The world catch of skipjack in 1968 has amounted to 253 thousand tonnes. Skipjack fishery in India is negligible, although resources are vast. Among the maritime State Kerala ranks first and Tamil Nadu second in annual landings of tuna and related fishes.

Tuna fishing in Minicoy island

The coral island of Minicoy in the Indian Ocean is the most important tuna-fishing center in Indian union. Tuna fishery is the most important industry of the island and chief product of export is the "masmin" or the cured and dried meat of tuna.

The species that contribute to the fishery, mainly, oceanic skipjack (Katsuwonus pelamis), while, small numbers of yellowfin tuna (Neothunnus macropterus) are occasionally caught. The frigate mackerel (Auxis thazard) has also been collected from the area: but it is doubtful if this constitutes a fishery of any magnitude. It is also reported that the little tuna (Euthynnus alletteratus affinis) are caught from the sea around. Tuna fishery is operative from September to April with peak season from December to March.

At the commencement of tuna season the large fishing boats locally known as ‘masodi’ which are kept covered on the shore during the monsoon period are pulled by about 50 or more persons and launched in the lagoon.

The skipjack is invariably caught near the surface and the gear used is the pole and line with lead coated iron hooks of simple type without any bard. The pole used is of light but strong bamboo of 3-4 meters in length specially brought for the purpose from Calcutta. The length of the line is equal to that of the pole and the hook is kept fixed to the base of the later, when not in use. The first 2/3 of the line is of cotton and the rest portion close to the hook is of steel wire formerly, but now of nylon.

An essential pre requisite before tuna fishing expedition, is the collection of baitfishes, which consists of a variety of small sized fishes in the lagoon. The most important among them are pomacentrids, which occur in very large shoals. They are caught in bait nets and stored in bait baskets.

About 20-30 people go in a boat at a time for tuna fishing. The fishing ground is generally close to the island and seldom beyond 16kms, depending on the success in locating the shoals. When a shoal is sighted, vessel is steered close to it and every one gets ready for action. The captain rushes to the bait well and scooping the bait fish with a small live bait baler throw them out on either side and thus, chums the tuna, which dart about actively feeding on them. At the height of this feeding activity 4-5 men take up positions with pole and line on each side of the boat on the platform near the helm and play the unbarded naked hooks trailing on the surface of the water. In the mean while, two persons from the sides’ splash water with water splasher over the hooks to mask them. When there is good fishing, each swing of the rod brings one fish, which immediately retrieved from the hook and sent sliding into the fish, hold below. Fishing generally lasts for 10-30 minutes and if successful, this time is enough to fill the boat with fish. Any hooked fish dropping into the water would scare away the shoal. Usually it may not be sighted again in the immediate viscinity. Another thing that scatter the shoal is the presence of sailfish Istiophorus gladius, which is said to follow the skipjack. If this makes its appearance, while the shoal is chummed close to the boat, the fishermen throw a wooden dummy painted like a tuna tied to a string and weighted heavily make it sink. The sailfish is said to follow the slowly sinking wooden dummy and fish (Xiphias gladius) is also said to be caught occasionally in this manner. The vessels that go out in the morning for fishing return invariably by sunset if not earlier.

Generally the skipjack weighs about 3-4.5 kg and measures about 0.5 – 0.75 metres in length. Almost the entire catch is cured and sundried and converted to ‘masmim’, which are exported. The price of dried product in the island is around Rs. 150 – 200 per kg.

The success of pole and line fishing depends on the following factors:

Availability of fishable concentration of tuna.

Availability of live bait fishes.

Availability of experienced operative personnel.

Separate arrangements for collection and timely supply of live bait fishes will save the time and more time can be spent for the actual fishing operations.

Introduction of bigger sized boats, which can carry at least a day’s catch, can save the waste of times in coming and going and unloading catches. By doing so more time could be spent for actual operation.

By installing radio telephone equipment on board the vessels, a large number of boats can avail the opportunity of fishable concentration of tuna in different areas with in a shorter duration.

Mechanization of tuna vessels will help in minimising the cruising time to locate shoals and utilising maximum fishing time.

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Technologies
(Fisheries)