SPC/ 22/WP.14 27 July 1990

ORIGINAL : FRENCH

SOUTH PACIFIC COMMISSION

TWENTY-SECOND REGIONAL TECHNICAL MEETING ON FISHERIES (Noumea, New Caledonia 6-10 August, 1990)

FISHING TECHNIQUES USED AROUND FISH AGGREGATION DEVICES IN FRENCH POLYNESIA

by F. Leproux, G. Moarii, S. Yen EVAAM, B.P. 20, Papeete, Tahiti, French Polynesia

643/90 SPC/Fisheries 22/WP.14 Page 1

FISHING TECHNIQUES USED AROUND FISH AGGREGATION DEVICES IN FRENCH POLYNESIA

Mooring FADs in French Polynesian waters, which began in June 1981, has had a favourable impact on local fishermen who, although they were sceptical to begin with, have come to use this assistance increasingly, many of them finding it very helpful.

The techniques of fishing around FADs have changed over the years and in 1990 four are still currently in use, while new techniques are constantly being developed and taught in order to obtain better yields.

1. FISHING TECHNIQUES

1.1 Handline fishing

Many small boats (3 to 6m) do deep fishing near FADs when a school of tuna is present. The handline is made of nylon line of 130 kg and a tuna hook (cf Diagram no. 1, Plate no. 1). The bait used varies with the season: thus "operu" (Decapterus macarellus), "ature" (Selar crumennhialmus), "numa" (Mulloidichihys samoensis), "marara" (Cysselurus simus), and fillet (Katsuwonus pelamis) are the most commonly used. The technique consists in placing this bait low down in the school. In order to facilitate the drop of the line, a stone is fixed to it temporarily. When the considers that he has reached the required depth, he gives the line a sharp jerk upwards which releases the stone and also some crumbs which awake the tunas' appetite. This ancestral technique still has many followers. Originally it was used in the "tuna holes" and now it is gradually moving towards the FADs where catches are more numerous. Two years ago the method was improved by the addition of buoys with buoyancy of 15 to 20 kg which retain the line on the surface thus making it possible to release several lines from one boat.

1.2 Vertical longline

1.2.1 Manual vertical longline

In order to restrict the number of lines and improve productivity, EVAAM has set up a fishermen's training programme which, amongst other things, is designed to develop the technique using a vertical longline with several hooks. This longline is made up of a mother line of monofilament 50 to 150 fathoms long, and 140 to 200 km strength, to which are fixed by rapid fasteners several branchlines of 3 fathoms' length, each ending in a self-hooking hook (Diagram no.2).

A weight of 1.5 to 2 kg ensures the drop of the line. We generally recommend that no more than 5 branchlines should be used if the longline is to be hauled in by hand. A buoy of 16kg buoyancy maintains the longline on the surface and a smaller buoy with 5 to 6 kg buoyancy acts as a pilot indicating when the fish bite. The bait most commonly used is "ature", "operu" or skipjack fillet, "operu" being the most liked. SPC/Fisheries 22/WP.14 Page 2

1.2.2 Vertical longline on a winch

The technique is exactly the same as that used with the handline with several branchlines. However there may be a greater number of hooks. We advise a maximum of 10 branchlines when a manual winch of the FAO type is being used; construction of this type of winch is included in the training given to fishermen who own small skiffs (poti marara).

Use of the manual wooden winch has developed rapidly in the Tuamotu Islands since introduction of FADs; but the "poti marara" of Tahiti are coming around to its use more slowly, for it is difficult to change people's habits even when the likelihood of larger catches is proved.

As an experiment, 10 hydraulic winches will be fitted on skipjack boats at the end of 1990.

1.3 Pole-and-line fishing

This is done almost exclusively from skipjack boats, which are 10 to 12m long, built of wood and carry a crew of only 3 or 4 men (cf. Plate no. 2). The technique consists in arriving at the FAD at dawn, when the tuna school is moving away to feed.

All the fishermen have to do is to follow the school and wait for the birds to signal the presence of a school near the surface. The captain's skill lies in situating the school exactly behind the boat. To catch small Katsuwonides (skipjack), bamboo poles are used. The lure is made of a hook without a barb to which is attached a piece of polished pearl shell. The pearl shell lies on the surface of the water and attracts the fish. Holding the pole with two hands, the fisherman gives it a sharp jerk and brings his catch into the boat; he continues likewise until they leave the school. An assistant meanwhile guts, cleans and stores the catch. When yellowfins are present, the fisherman more often uses a "mushroom" made of a leaded hook without barb, the upper extremity of which is covered with a shiny metal (stainless steel or aluminium). No bait is used. However, to keep the tuna near the boat a piece of fish maybe dropped into the wash of the propeller. It is known that tuna always rise to the source of bait when they are looking for food.

The skipjack boats do not carry on this kind of fishing very much in the neighbourhood of FADs where small skiffs are doing deep fishing.

The two techniques are in fact incompatible, because the one waits for the fish to come to the surface while the other keeps the fish at depth by placing bait at a depth of 50 to 200m. We are therefore obliged to moor DCPs more than 15 miles from ports, where the marine regulations in force prohibit small boats.

It should be noted that many skipjack boats are taking up the so-called "stone" fishing technique (Chapter 1-1) during the off-season. SPC/Fisheries 22/WP.14 Page 3

1.4

This technique is regularly used by all types of fishing boat, A hand-reel or a pole with reel is used and, although it never brings in a large yield, it provides an appreciable addition to the daily diet. However, it does involve considerable expenditure on fuel and is therefore practised only if the other techniques are really not productive.

1.5 Night fishing

This technique is used near FADs when the sea is calm, and results in larger catches of tuna than by daytime. The technique is different; it consists in situating at lm depth a source of light of 40 to 60 watts to attract the fry, bringing the fish to the surface by throwing handfuls of skipjack chopped small every two to three minutes and sinking the line or lines between 20 and 40m depth with whole fish as bait ("operu", "ature" or skipjack fillet). It is better not to get too close to the FAD because sharks would rather spoil the fishing. This technique is beginning to disappear, on account of the good results obtained in daytime fishing (Diagram no. 3).

II. SPECIES CAUGHT

They are mainly tuna: skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares) on the surface between 40 and 100m depth, a large proportion of yellowfin; between 100 and 200m depth albacore (Thunnus alalunga) and less frequently bigeye tuna (Thunnus obesus). Occasionally blue marlin (Makaira mazoira), wahoo (Acanthocybium solandri) and dolphin fish (Coryphaeus hippurus) are also caught.

Although little reliable data on this subject is available at present, we estimate the proportions of species fished at depth to be 90 per cent tuna and 10 per cent other species.

Ill. CONCLUSION

As types of vessel change so will fishing techniques. However, we try to concentrate on improving techniques that are currently in use and which should enable an artisanal to augment its productivity considerably despite very marked under-fishing at a certain period of the year. Changing from the handline to the vertical longline mounted on a manual winch is one stage, and use of a hydraulic winch is another; the principal aim is to determine and to implement the technique or techniques that are the most efficient, having regard to the type of fishing carried on around the FADs. HANDLINE WITH A SINGLE HOOK

In order to determine the depth, the line is marked off by binding in nylon cord. The first mark is placed at 40 fathoms. This mark is repeated every 10 fathoms until a depth of 160 fathoms and sometimes more is reached. To distinguish the depths, the marks are painted different colours.

buoy (15-20 kg buoyancy)

reel of nylon

monofilament nylon 130 kg

depth mark

lead sinker (200-500 gr)

swivel

monofilament nylon (90-110 kg)

ta self-hooking hook (no. 40-45)

DIAGRAM No. 1 VERTICAL LONGLINE

Descriptive diagram

16 kg buoyancy

6 kg buoyancy

self-hooking hooks No2. 36 to 40 DETAIL:

300 a 350 m

15 m (7 fathoms);

monofilament nylon (100 kg)

sinker 1.5 - 2.0kg

DIAGRAM No. 2 NIGHT FISHING

Position of boat

floating anchor

Cord holding back line, breaks when pulled

35 m line basket

\ , ^ Position of line

LINE 200 m of braided nylon 0 5-8m / LIGHTING basket No. 36-40

battery

7m nylon single

under-water lamp Placement of hook sinker 50 W 12 V ^ ' • "* M5: iJMnerse bulb self-hooking ' before connecting hook

DIAGRAM No. 3 HANDLINE FISHING

Winding line round temporary sinker

Bouy to keep line on surface PLATE No. 1 POLE AND LINE FISHING

12m Skipjack boat made of wood

Fishing off with bamboo poles

PLATE No. 2