SPC/Fisheries 14/WP. 15 22 July 1982

ORIGINAL : ENGLISH

SOUTH PACIFIC COMMISSION

FOURTEENTH REGIONAL TECHNICAL MEETING ON FISHERIES (Noumea, New Caledonia, 2-6 August 1982)

FISH AGGREGATING DEVICES or PAYAOS

by M. de San FAO Associate Expert Project RAS/73/025 Regional Fisheries Coordinator (South Pacific)

SUMMARY

Briefly describes history and use of fish aggregation devices (FADs or Philippine "Payaos") in the Philippines, Hawaii and the South Pacific. Factors to be considered in the design and construction of an effective FAD system are discussed in detail, and specifications and component cost estimates are provided for a suggested "optimum" design.

The author suggests economic, bathymetric and other physical factors to be considered before deploying FADs, and describes a recommended procedure for anchoring them at sea. He briefly comments on fishing methods which are used in conjunction with FADs, and suggests further areas for research - particularly in the design and use of sub-surface appendages which appear to be a key element in attracting fish.

885/82 ?Is DP ,'?AS/7 3/025 Workinp Paper June 1932

FAT

FISH AGGREGATING DEVICES

or

PAYAOS

Notes on constructions, together with some criteria for placement and examples of utilization

prepared oy

M. de San FAC Associate Expert Project RAS/73/025 Regional Fisheries Coordinator (South Pacific)

FOOD AND AGRICULTURE OPGANIZATION OF THE UNITED NATIONS Rome, 1982 - iii -

CONTENTS

Page

I. INTRODUCTION 1

II. GENERAL DESCRIPTION AND CATCH COMPOSITIONS 1

III. THE FAD WORKS, BUT HOW AND WHY? 2 (a) Tuna and Baitfish Behaviour Around FADs 2 (b) Suitable Sites for FAD Anchorage 2 (c) How Essential are FAD Underwater Appendages 3 (d) Summary 3

IV. FAD DESIGNS, SPECIFICATIONS AND COST 3 (a) Quality, Cost and Durability 3 (b) Description 4

V. WHERE AND HOW TO SET IT 8 (a) Where? 8 (b) How? 10

VI. THE WAY TO USE IT 10 (a) Artisanal Fisheries 10 (b) Industrial Fisheries 11

VII. MAIN PROBLEMS 13 (a) The Loss 13 (b) The FAD Does Not Work 14 (c) Loss from Fishbites 14 (d) Who Uses the FAD 14 (e) Sharks 14

VIII. CONCLUSION 15

ACKNOWLEDGEMENT 16

BIBLIOGRAPHY 17

These notes are designed for discussion and information. The technical specifications and recommendations included should not be considered official FAO recommendations which will be prepared when more data and information from different parts of the world are obtained and analysed. _ 1 __

I. INTRODUCTION

It has long been known that floating or drifting objects in tropical seas attract pelagic fish species, but locating such objects has always been an element of chance so a natural evolution was the development of tethered or anchored objects to which fishermen could return at will. These anchored rafts or buoys are termed Fish Aggregating Devices (FAD ) in the Central North/ South Pacific, and "payaos" in the Philippines where they were first introduced and used on a large scale nearly1 a decade ago. The US National Marine fisheries Services Honolulu Laboratory, was instrumental in developing designs and deploying experimental FADs in Hawaiian waters - which has since deve­ loped into a relatively large-scale programme under the auspices of the State of Hawaii - and in introducing the technology to American and. Western Samoa. Virtually all South Pacific countries now have, or are planning, FAD programmes. This paper is intended as a brief summary of FAD construction details, .some factors to consider when anchoring them, use of FAD by the artisanal and industrial fisheries, and an outline of past and future problems. It poses some hypotheses as well as questions concerning the.factors and their interactions that make FAD work. This document cannot be considered a definitive treatment of the subject since all regional experience and data are not available nowj rather, it is a general information paper which it is hoped will be of interest and assistance to those planning to use FAD in fisheries developments particularly with respect to designs which provide an optimum service life and efficiency, and their effective deployment..

II. GENERAL DESCRIPTION AND CATCH COMPOSITIONS

FAD are essentially rafts or buoys anchored in depths ranging from 270m.to "3 700 m (150-2 000 fath). There are a number of designs, ranging from simple clusters of bamboo poles held inside used rubber tyres, through foam-filled drums encased in a steel framework, aluminium foam-filled catamaran'hulls, foam-filled large earth-moving equipment tyres, and FADs of fiberglass and rotationaily moulded plastic are on the drawing boards or being developed. More details on these designs aire contained in a later section.

It appears that Sub-surface appendages comprised of vegetable matter such as palm fronds, or artificial materials such as old tyres, cargo or olf nets laced with vegetation or free streaming lengths of polypropylene strapping material, and rope yarns or other items, play an important role in attracting the larger pelagic fishes in terms of quantity and time. The actual reasons for this are unknown but some reasons have been proposed (see part III).

Fish catches in conjunction with FAD are predominantly skipjack (Katsuwanus pelamis) and yellowfin tuna (Thunnus albacares), but there are significant by-catches of other pelagics such as dolphin (family Coryphaenidae), mackerel (family Scombridae), barracudas (family Sphyraenidae), rainbow runners (family Carangidae) 5 sharks, etc.

Matsumdtb et al. ,(Sept. 1981) note that catches by livebait pote-and-line vessels and purse seiners are primarily tuna species and,though the majority of fish taken by trolling and handlining around FAD are also tunas, catches of other pelagics are substantial, particularly dolphin. As might be expected, the species composition can change from one FAD to another. - 2 -

The annual production from a good, well-placed FAD fished with a purse seine could be in the order of a few hundred tons, that for pole-- and-line fishing somewhat less but still substantial (in Fiji approximately 130 t were- taken, by-one vessel around three FAD over a month) > and even for, the ,81113117-80310 artisanal fisherman production can be significant - e.g»,i the>handline and troll fishery for yellowfin reportedly produced 18 000 t during 1980,:in the .Philippines (E. Gonzales, 1981).

One, of the most obvious benefits from u^ing FADs is the savings in fuel,,fpr both,the. industrial and, artisanal fishermen since manyof the hours formerly spent steaming in search of fish schools are obviated to a great extent • ; ...... -.f .; ... • -.-.• •,•-..; III: THE FAD WORKS, BUT HOW AND WHY?

" FADs definitely work but understanding the apparent reasons and their interactions is difficult and will continue to be sd'until more research has been accomplished, and more data collected and collated. With a better knowledge of these reasons or factors, FAD designs will undoubtedly be improved'to make them even more attractive^ and the m6st suitable locations for anchoring more; easily identified. It is therefore important that FAD promoters and users keep1 detailed'records for each FAD which note the location, depth, kind of appendage, catches and species composition; losses, etc. Such recordings and observations '' would show more about: '

(a) Tuna and Baitfish Behaviour Around tfAD ;

Tuna: Concentrations range from zero to 100 t or, more^. and quantities change continually as schools leave and others take their place, Matsum'oto et al., (Sept. 1981) note that, "The fish aggregating devices ,attracted a11 sizes of tujxas ranging from below 2 lb to over 20 lb. Small fish below 3-.4 lb (skipjack tuna, yellowfin tuna, kawakawa (rainbow runner), and a few bigeye tuna) generally remained in the immediate vicinity of the buoys and ranged. in depth from the surface to over 250 ft. Larger fish, mainly skipjack and yellowfin tunas, roamed over wider areas from 0.25 mi to 3 mi or more from the buoys during the day. These fishes apparently, returned to the buoys at night since the day's first catches by bait boats were invariably made at the buoys at day-break. The bait boats moved away from the buoys after sunrise as they continued to fish.the schools."

This tuna night behaviour is confirmed by purse seine vessels fishing . ,.<• around FAD by night in the Philippines as noted by R. Gonzales.

Baitfish; Flocks of birds working around FAD indicate the presence of baitfish but there is little if any information available concerning . . ,.. the apparent abundanee of baitfish around FAD or their behaviour. ,

(b) Suitable Sites for FAD Anchorage

(Sites with known tuna presence,optimum depth, distance between FAD and distance from reef - see Part V (a)). '',' ... , ..'.'... - 3 -

(c) Just how essential are FAD underwater appendages for attracting and holding fish, and what is the optimum design?

According to Matsumoto et al.,the reduction in fish aggregations and catches at FAD that had lost the appendages (or drapes) were quickly noted by Hawaiian fishermen arid there was considerable activity to have them promptly replaced.

Besides9 we can expect that9if experience had taught that anchored FAD work as well with or without appendages>fishermen would have concentrated on the simpler version.

(d) Summary

Following is a diagram showing some of the possible reasons for tuna presence around"FAD (raft and appendages), interaction is probable between the different factors without excluding that one or two are more important.

• , '•-"" Food Factor

Food Factor (small animals) '""»»»»^««™<™'»'»-»- J - '"'" _„*•• Cleaning Station •--..'"';'"'"'~'''"""»^,«a,,;j Shade Tuna „, .. „ ' i;-- / J 4-u cu i • ti - Shoaling Factor (and other Shoaling Factor

' fish) '•'••«...;.. •'..•?••"'• .- .'

•x ~ - Shade .<-•'' "• ' '""--• Navigation Reference

From this it is obvious that there is a great deal of scope for further research.

IV. FAD DESIGNS, SPECIFICATIONS AND COSTS

(a) Quality, Cost and Durability

Perhaps two of the most important considerations in planning a FAP deployment programme are to obtain the greatest durability or service life at least cost« Durability is a function of quality just as cost is a function of depth and quality of material.

Another factor to consider when determining investment in a FAD is its location. Those deployed in very exposed areas or subject to strong currents should have stronger, better quality materials than those located in compara­ tively sheltered waters to ensure maximum service life.

Yet another factor is the likelihood of small artisanal boats mooring to the FAD buoy for handlining, which creates an additional load on the , anchor line ^'particularly if one or more boats moor athwart the current so more handlines"can be used with maximum separation between them. ,

The FAD planner then has two options from which to chooses

(i) Using more expensive, higher quality materials to ensure maximum service life with costs, for example, ranging from about US$ 1 130 for - 4 - a complete, anchor line (20 mm rope and associated hardware) having a 1.4:1 scope for a FAD set in a depth of 5Q0 m (273 fath) to US$ 3:700 for one set in 1 645 m (900 fath). Additional costs would be for the hardware, and materials used for the appendage, FAD navigational markers such as flashing buoy light and radar reflector, the FAD buoy and the anchor block. The quality and durability, of the FAD buoy should be commensurate with those of the anchor line to protect the overall investment. ^

(ii) Using lighter arki less expensive materials throughout -i.e., 12mm or less diameter rope, lighter associated hardware, appendages made off scrap rope and vegetation, bamboo FAD buoys, etc. - costs could be reduced by about 40-50 percent -(the anchor line for a FAD set in 500 m being on the order of US$ 540 as opposed to US$ 1 130), but this could well be a matter of false economy in many instances.

.In Hawaii (Matsumoto et al., Sept. 198,1) the first generation of FAD . moored,. in locations designated as A, B, C, and D survived for an average of two months. An improved, second generation lot of FAD survived an average of 12 months, with a maximum of 19.75 months. One deployed by an FAO fisheries project off Penrhyn Island in the northern Cook Islands is still in place after 19 months. •• < :•

Conclusion r;' •

It is clear there are different levels of budget, objectives and labdur costs available but,whatever the choiceythe purpose of this paper is to try to optimize it. Some of the suggestions do not necessarily mean a large increase in the price. Concerning the FAD itself, this paper describes and comments on different, options, but the materials and techniques to increase the FADs life or its efficiency receive special attention.

Description

(i) Material for one FAD Estimated Price Quantity Unit US$ (Ex-stock)

1. 1/4" safety chain shackles (bolt and nut and safety pin) pin diam. 5/16" for appendages as required 2. 5/8" safety chain shackles (bolt ' , „. ; . and nut and safety'pin) piry diam. ' T ,i,.. ,. ; 3/4" (to fit 14 mm diam. chain) 14 pc ... 3.18 3. 3/4" safety chain shackles (bolt and nut and safety pin) pin diam. 7i/8" 1 pc 4.30

4. 19 mm eye and eye swivel . 4 pc 13.50, , i ., 5. Rope thimble for 20 mm diam. rope as required 1.50 6. 20 mm diam. rope., polypropylene three-strand .(colour, red/brown) as required , 125 (GIF S, Pacif ' .'-, , " " . 220 in. coil.,,,.,..; 7. Short link chain 14 mm 100 m 6.15/m 8. Short link chain 7 mm for appendages as required

9. Eyebplt, material SS41, 22 m diam., f •.-. h-; eye ID 50L mm, length 220 mm plain end 5 pc -,7'.'..5'0-. _ 5 - . Estimated Price 10. Fishing buoy light, flashing type, Quantity Unit US$ (Ex-stock) automatic on-off with sun switch, dry cell battery (AM-1) suitable for counting on flagpole 1 pc 30.00 11. Radar reflector 1 pc

N.B. - All steel material must be .hot-dipped galvanised - To avoid any electrolysis problems all fittings should be of uniform metals

The price cited were effective as of late 1981. The hardware comes from Japan, the polypropylene rope from New Zealand and the flash buoy light from Canada.

(ii) Description and reason for the choice

1. The anchor blocks. It is felt that three small rectangular anchor blocks are more effective than one or two larger blocks. They are easier to handle than large ones arid",although lighter, have about the same holding capacity. It is suggested the anchors be made from reinforced concrete. The approximate weight for one block out of the water is 400 kg and its submerged weight is about 240 kg. If the anchor blocks are located in places with strong current or inclines with slippery surfaces, then concrete steel Tebars (3/4 in)project 5 cm from the broad face are added to minimize slipping.

The cylindrical anchor block without any steel bar projections should not be used because of a tendency to roll on the sea floor. This is important because, many FAD are placed on the slope of the continental shelf.

2. The Rope. Use of an i8~20 mm diameter polypropylene 3-strand rope • is suggested because it has the requisite strength at the lowest cost. Another consideration is buoyancy, which is particularly important for the anchor line bottom section to prevent the rope from chafing on coral heads, pinnacles, etc.

Why 18-20 mm of diameter?

For the following reasons :

- Fishbite (see part VII (c)) - Hawaii use 18mm - Western Samoa use 19 mm - Fiji Fisheries use 18 mm and for the. future 22 mm - IKA Corporation (Fiji Tuna Company) use 18 mm - Nelson Company (NZ) deployed more than 90 FADs in Fiji waters using 12 mm rope and after very high losses they are planning to use 16 mm - Co6k Islands use 20 mm

Scope to depth ratios of 1.05-1.3 and even 1.8 have been used. But very low scope ratios were, recently, recommended. About /4 depth below the surrace a chain section is installed of sufficient weight to overcome at least 60 percent of the rope's buoyancy for the expected depth.

Elements; - Depth 1 000 m - Density of polypropylene rope = 0.91 - 1 coil of rope = 220 m - Buoyancy of 100 m of 20 mm polypropylene rope = 1.59 kg - Weight of 1 m of 14 mm chain in the water = 3.65 kg - 6 -

Calculations - Given 400 m + 200 m of rope to be overcome by the counterweight chain - Buoyancy to be overcome; 6 X 1.59 kg = 9.54 kg - Minimum length of the counterweight chain: 9.54 kg . = 2.61 m 3.65 kg/m

Coils of 220 m are standard but it is possible to purchase-continuous! length in multiples of '220- m- (440 -m, 660 m, 880 ni, etc.).

Because of the numerous rope splices required to construct a deep mooring line, it is imperative that the splices are securely made. It is suggested that each splice be made at least 8 in long at the thimble point and at the short splice joining two coils ,6 tucks be used each way. Both must be seized tightly with nylon twine. The end of each 3-strand should be burnt, whipped, seized or taped.

No knots should be made in the rope because they weaken it by more then 30 percent.

3. The Swivelso Swivels are indispensable. They prevent the rope from twisting and braking. Use of 4 swivels, the eye and eye chain type (see figure) is suggested.

The sealed ball bearing type would be superior but is expensive-!/. Perhaps one should be used in construction with three eye and eye chain swivels, and would replace Swivel No. 1 (see figure).

4. The Chains, (see drawing). Several pieces of 14 mm diam. chain are set from the raft to the anchor blocks,

- 3 pc of 3 m. to attach the raft if a three-part bridle is used. - 1 pc of 40-50 m as a pennant below raft so the rope is beyond the maximum growth zone (cutting danger by organisms), protected against vandalism and shark-bite in the fishing zone. - 1 pc of 20 m before the anchor blocks. - 2 pc of 3 m between the anchor blocks. - A 7 mm chain is used for the appendages.

5. The Shackles. An informal workshop on FADs held in Honolulu,23 October, identified 17 definite and 4 probable causes of mooring line failure in the losses of 33 FADs. Of these 17 definite causes,, two.were attributable to shackles and failure occurred as the "result of the pin working itself loose.

The workshop report advised to secure and coat the pin with eppxy or fiberglass resin. This in preference to securing with galvanized wire which can be too small and corrode in a short time,

Thereare some restrictions ii\ the practical use of resin since at least one or more shackles may have to be secured aboard ships immediately before anchoring the FAD.

. . . . '''.•• . It is also questionable whether the crew will give the requisite attention to the mixing, pot life, proportion, dryness, cleanliness of the shackle and different other matters necessary for proper application of the resin.

U Estimated price US$ 100-250 _ 7 -

Consequently, safety chain shackles with bolts,.nuts and safety pins recom­ mended in the book "Buoy Engineering" by H.O. Berteaux, appears to be a more satisfactory choice in lieu of the screw pin types.

6° The Raft. Western Samoa successfully uses and occasionally exports a small aluminium catamaran filled with polyurethane foam.

It consists of two cylinders made of marine grade aluminium connected with aluminium hollow beanis welded to the cylinder. It has three 1/2 in stainless steel "U" bolts for anchorage attachment and two 3/8in stainless "U" bolts for appendages attachment.

The idea is to have a raft with little maintenance, long life, minimum corrosion, little water resistance and reasonable cost,

The raft must have a minimum of 600 litres of buoyancy to overcome:

- the weight of 50 m of 14 mm chain (about 200 kg); - the strength of the current which pulls down the raft; - the weight of one man who must be able to stay on it for maintenance.

If small boats are allowed to attach themselves to the raft or if..-. it cannot be prevented, it is better to provide the raft with a special mooring point with breaking strength much less than that of the anchor rope. •••..,

In the Pacific other models exist such as an assemblage of foam-filled 55-gallon drums encased in a structural steel framework, very large foam- filled tyres, and wooden rafts.

N.B. All are filled with polvurethane foam '.,

A raft in polyester and fiberglass with metal frame for strong anchoring point represents a possible option, as well as disc-shaped buoy design. There is also the less serviceable but inexpensive type in bamboo used in the Philippines. In this case a fairly large buoy is attached to the line which acts as a mooring point for the raft. If the bamboo raft is lost the main anchor line can be located by the buoy. To keep the raft afloat when the bamboo becomes water-logged, a couple of plastic balloons (60 litre each) are added. ' ....

7. The Appendages. The appendages are thought to be an important item of the FAD.

With reference to page 5 (,c) , it was assumed the concentration of fish around the FAD is less if the appendages are lost but this will not be known definitely without further statistical research. - 8 -

Generally. Appendages are fixed at depths of 5_25 m. Possibly the best appendages are coconut fronds, but they do not last longer than two-three months1. Old tyres (cut in two) and old nets are commonly used. Polypropylene strapping material fixed to a sort of giant ladder (cargo net) seem very promising.

Experiments' with different appendage designs are still going on and no doubt appendages will evolve^ in the future.

'Following are a few'factors which could be improved through further study and experimentation: kinds of material at lower cost, durability (resistance1 to the waves action), water resistance,, configuration, depth, where and how to attach them, a better knowledge of the behaviour of the tuna and the small fish, etc.

Discussion. The cufreiit idea is to fix the appendages from 5 m to 25 mbelow the surface for maximum primary production and the start of a food chain.

The appendages accumulate marine growth as food for small fish species, which attract larger predators,: which in turn attract even larger predators such as tuna, jacks, dolphin, etc.

Supposing 30 t of tuna around a FAD consume 10 percent of their weight or 2.5 t daily (Sund, Blackburn, Williams, 1981). It is difficult to believe that the daily primary production on the appendages (example 20 types) plays an important role in the food supply of the fish around the FAD. However, it cannot be definitely denied that the primary production (as well as the shelter provided and other factors) plays a part in the attractiveness of the FAD, and the schooling of a few fish could be sufficient to start attracting many more.

An interesting experiment would be to attach some deeper appendages in connection with those close to the surface. For example, attach them around 60-120 m (handline by night for yellowfin,see VII (a) 3) or deeper at the level where the zooplankton are during the day.

It is assumed that appendages play an important role in FAD effective­ ness. Then, as formal research requires time and appendages are relatively inexpensive,it is suggested not to be too miserly with them.

Perhaps also the number of appendages or their surface area volume has an influence on the time necessary to aggregate fish, both at the . ... . beginning or after a successful visit by a purse seine or pole-and-line boat.

V. WHERE AND HOW TO DROP IT

(a) Where ..-:...... ,'••.••••• 1. Experience has shown that FAD should only be set in places with known potential or tuna presence and not where it can be reached most conveniently

- It has often been suggested that tuna tend to be most abundant where their food is concentrated within areas of suitable temperature. Blackburn (1965; 1969b) strongly supported this view. The food consisting generally of active pelagic animals measuring from about 1cm to 10 cm: fishes, and crustacea are all considered as micronecton. (Sund, Blackburn, Williams, 1981). _ 9 -

- Suitable spots include wind-induced upwelling (coastal and equatorial) geostrophic upwelling and verticle mixing by-wind. Tuna are expected to be plentiful in those areas because of the micronecton unless the waters are too cold or turbid. (Sund, Blackburn, Williams 1981).

- As far as underwater ridges or seamounts create such upwellings, it would seem worthwhile to expend some efforts to sound out coastal areas with recording echosounders to locate them (the coastal and off-shore waters around all South Pacific countries are poorly charted). This would permit anchoring in shallower depths and thus minimize the cost of anchor lines.

'- The fronts which are boundaries between waters of different densities have also an important effect on tuna distribution.

- Surface-swimming tuna are often more abundant around islands and banks than elsewhere in the same part of the ocean. It has generally been assumed that more food is available on or around, or in associated fronts and eddies. (Sund, Blackburn, Williams,1981).

2. An interesting question that comes to mind is the optimum distance between FAD,„ particularly for large scale industrial fishing. Would two or more FADs anchored fairly close together attract and hold more fish over a shorter or longer period, or should they be separated by a number of miles for better efficiency?

3. The depth and distance from the reef must be taken into conside­ ration:

Several FAD were set close in-shore off Western Samoa as a convenience for village fishermen but their production has been generally poor.

Conversely, two,set from 12 mi to 12 mi offshore in about 900 fath, have been very productive.

Hawaiian experience (Matsumoto et_ al., 1981) indicates that buoys anchored in deep water within 2 mi of: the 1 000 fath ledge (curve) were particularly successful. •-•''.

4. Note that the bottoia (or top of seamount) must be as flat as possible to preclude FAD anchors from sliding into the depths after a few weeks.

5. It seems important to make a marketing survey before deploying FAD.

Indeed different elements have to be taken into consideration: the dis­ tance' to a: good commercial market'(or a cannery for industrial fishing boats), the baitfish supply, the ice supply, the quantity of fishing boats which would fish around the FAD-, etc.

6. Conclusion; Experience gained in several South Pacific areas has shown that a FAD should be anchoreds

(i) In places with known potential or tuna presence^ (ii) not to° close to the reef or in shallow water a site chosen close to the 1 000 fath isobath seems to be a good location; - 10 -

(iij.) on the ,tops of seataounts;, (iv) where-the bottdm is reasonably flats (v) where there are potential markets nearby.

< It is important to keep catch records for each FAD and to learn , f or, the future from both, good and bad experiences. ., ...

(b) 'How

First, the right location must be determined in advance by a careful seabed survey and for that a high, power precision echosounder is necessary, (In the South Pacific region, FAO/UNDP project RAS/73/025 has a portable unit with depth range.up to 2040 fath for loan.) Fallowing is a.brief description of what is perhaps the safest method . of deploying a FAD:

(i) , obviously, a prerequisite is a calm sea and good weather; (ii) if the ship does not have a boom for Vanging the anchor blocks over the side,then they should be mounted on a simple ramp or positioned so they can be'pushed'• overboard at the proper time; (iii) the chain pennants and anchor rope should be flaked out carefully so, there is no chance of fouling or snarling when it is payed out, and all final connections made; (iv) when the anchoring location is reached, the FAD is launched and 1 preferably in towJ of an outboard-powered skiff which pulls out the anchor line in a large circle as shown in the sketc'H below. This permits the ship to hold station over the desired location 1 and minimizes any drag on 'the anchor blocks by the FAD which could cause the anchors to miss the chosen spot; , , (v) when the entire anchor Line has been payed out and the skiff and FA$, return to the ship, the anchor blocks are dropped. Of course., the ship must be outside of the anchorline circle since part of it is still likely to be floating.

VI THE WAY TO USE IT

The best time for fishing around the raft seems, to be early in the mornings late, in the afternoon,, and during the night for purse seining and handlining. '. ,.

(a) Artisanal Fisheries

(i) Trolling; trolling for tuna is well known but this technique is becoming economically less viable with the increase of fuel costs.

However, trolling in connection with FADs saves a great deal of time and fuel 'that is normally' spent looking for fish; 11 -

(ii) Small Scale pole-arid-line with baitfish. This method is also used in Western Samoa with very promising results. A 9m catamaran is used equipped with two bait tanks (10-15 buckets) and a water spray bar across the transom. A portable water pump (5 hp) is used for both water circulation in the bait tank and the spray. The boat cruises slowly around the FAD, or through the bird flock(s), bait is thrown into the water and in 15-30 minutes 100-200 fish may be caught with four fishing poles.

One main difficulty with this technique is having an adequate supply of baitfish available which is imperative if the method is to be success­ ful. In Western Samoa there is an FA0 acquaculture project which pro­ vides Mollies (Poecilia mexicana) as bait.

(iii) Handlining by day and by night with light. In the Philippines this technique is used widely. More than 18 UUU t ot tuna were caught in the southern part in 1980, mainly yellowfin (ThunnuS albacares) at depth of 80-180 m, and over 200 m for the large fish. (Ruperto A. Gonzales, 1981).

The Hawaiian experience is also interesting. Following are some extracts from the report by M. Mataumoto, T.K. Kazama and D.C-. Aasted, -(1981).

"The buoys off Kona also attracted many commercial skiff fishermen using the "drop-stone" method of fish for 50-200 lb yellowfin tuna usually accompanying porpoise schools. The gear is essentially a handline using 10-12 in mackerel scad as bait. The hooked bait is laid on a smooth stone weighing about 2 lb together with a package of mackerel scad chopped up and wrapped in a chum bag. Both bait and chum bag are bound to the 1 stone by a few turns of the mainline arid secured with a slipknot. The stone is lowered 30-60 fath and is jerked free to expose the bait and chum. Fishing was done by positioning the skiff in the path of a porpoise school and dropping the line as the school approached the skiff. The buoys "enabled fishing during periods when porpoise schools were absent from the area.

One report in June 1978 indicated that up to 50 trolling and handline boats fishing at G. brought in 35 000 lb of yellow­ fin tuna and marlins on one weekend and that the drop-stone skiffs averaged from three-tout yellowfin tuna per day." ' In Fiji the Fisheries Division has tried handlining by night around . .FADs on seven different occasions with poor success due to shark attacks.

(iv) ; Gijlnet around FAD.. This method is mentioned only as a possibility since itis.not known 'now whether gillnetting in conjunction with FAD ,..has been attempted. , •

Industrial Fisheries

(i) Pole and line. Following is a brief description of the impacts made by FADs on the pole-and-line fishery in Hawaii (Matsumoto, Kazana, Aasted, 1981). - 12 -

• . "The usual fishing routine followed by bait boats was to spend one day, occasionally two, fishing for baitfish and one or two days, sometimes three, fishing for skipjack tuna. ; Consequently^30-50 percent of the time was lost to baiting .^operations. Additional time was lost at sea due to scouting • r,.v---;.v for tuna schools.

"The introduction of the buoys eased the stringent demands on the supply and condition of baitfish and eliminated scouting -P time and time lost in pursuing schools. Night baiting often nwas sufficient ;to provide baitfish for a.day's fishing, ..Consequently „ fishing routine was reduced to baiting at night and fishing the next day. If the catch was sufficiently large, the boats would return to port well before noon and prepare for night baiting. Following this routine, many boats were able to fish five-six days a week. One boat fished eight jiays during a nine-day period. On numerous occasions vessels visited buoy A .with,,les,s than the minimum amount of baitfish normally required for.a day's fishingj and with baitfish in slightly weakened condition because of the short distance from port and^fishing around it required less insentive chumming."

(ii) Purse Seining. Mr Ruperto A. Gonzales (Philippines) was in Fiji during July 1981 as an FAQ consultant to share his experience on purse seining in conunction with FADs which has evolved into the primary tuna capture method in the Philippines over the past decade. Please note that the Filipinos fishermen have an experience in advance of five to : ten,;years in fishing around FAD.

Given below are the main recommendations and concluding remarks from, Mr Ruperto A. Gonzales' report:

Recommendations for each purse seiner

1. Two utility .boats, 5Q-60: ft in length, should be acquired to service the rafts. These should have a 20-25 kW generator and at least sixteen 1 000 W lamps on each. The boats are used to maintain enough palm fronds at a depth of at least 2,0 m or more and to light up the rafts for several nights until a good amount of baitfish are seen sheltering under or around them. The boats also handline for testing at what depths the fish are biting and learning the species, size and volume of fish that are aggrega­ ting and informs the purse seiner by radio. The utility boats assist in placing the rafts and in addition keep the net open by slowly towing the float- line after the net is set. In this way the fish are kept alive even if the catch is large. The boats pan sometimes catch bait fish and release them in the vicinity of the rafts.

If the utility boats are riotavailable , two 1 000 W underwater lights can be used, turned them on at sunset and off a couple of hours before setting the riist.Abov e water lamps are also required-four 500 W or two 1 000 W, at a height of two-three ft' above the surface, and these are to be left on after the underwater lamps have been extinguished. Eye brand bulbs from Japan are recommended because of their durability. „ 13 -

2. An aluminium boat about 16 ft long should be acquired which has a three kW Yanmar water-cooled generator set. The boat should have a 25 hp outboard motor for manoeuvring the boat to the centre of the net during setting and hauling operations. Someone must tend the light, adjusting its intensity to keep the fish attracted. The same kind of fish may need varied intensities of light at different times. At times the fish need very dim lights to attract them to the light boat during the setting operation al­ though normally a 2 000 W light is sufficient. Care must be taken to keep at least one above water light on before all the underwater lights are switched off.

3. Thirty or more rafts should be anchored in prospective areas. It takes about one month for the raft to accumulate fish and assuming that one raft is fished every day, 30 rafts will be needed. To reduce the present losses of rafts, a 16 mm or larger diameter polypropylene rope should.be uti­ lized for the anchor line and the three concrete anchors should be made rectangular in shape and weigh around 400 lb each.

4. The last and most important recommendation is to increase the depth of the net to at least 120 fath. rThis is critical because the waters in Fiji are clear and there is no pronounced thermocline. Furthermore, yellow- fin tuna were observed at 110 m or 60 fath and the working depth of the present nets is only about 45 fath. Unless the depth of the net is increased, no amount of improvement on the other factors will bring success to the project.

Concluding Remarks

For a successful realization of the skipjack and tuna development programme, some kind of working arrangement between seiners and pole-and- line boats should be reached. If the pole-and-line boats feel that the rafts will be beneficial to them (and as shown by recent experience they are) then they should be requested to set out their.own rafts or,pay 10 percent of their catch to the raft owners. No pole-and-line boat or gillnet'ter should be allowed to fish within one mi from a raft without the owner's permission.

Some enterprising Filipinos have deployed rafts and requested the purse seiners to set on them, around which fish aboundj for a 25 percent share of the catch. This is an accepted practice in the Philippines.' For speedy success of this;development programme, may there be understanding and coope­ ration between fishing people with conflicting interests.

VII MAIN PROBLEMS ;i ^

When a country in the South Pacific deploys FADs, the loss rate or malfunction in the first six months may often exceed 50 percent (and even this is an optimistic figure). :--•'

(a) The Loss ' ,; -: - ' '"''''.

'•' Everthitig must be done to; avoid FAD losses since each represents a substantial investment in time, labour and material. The description of material in part IV is aimed at minimizing losses.

Recommendations in part V are to assist in finding a suitable site for anchoring. A serious problem can be the possibility of vandalism by local fishermen who cut the lines because they are upset at seeing' commercial vessels catching fish near their islands and traditional fishing grounds. " - 14

If FAD replacement is necessary, do it quickly for two reasons:

(i) to make the FAD available td fishermen as soon as possible (ii) if the. FAD is replaced in two-four days, the time to "Prime and Pump" will be much shorter than after one month. rIt is suggested that ^PAD materials should always be in stock for fast replacement.

(b) The FAD does not work ''..''' '/ '

It could happen that the FAD does not aggregate fish properly after two or three months even during the best part of the season. In this case, if it is tecnnical.ly possible, the best thing is to move it to a better location.

The FAD raft normally starts to aggregate fish after three-four weeks.

(c) Loss from Fishbites

Following are extracts from a manual on "Deep Sea Lines Fishbites" by Bryce' Prindie and Robert G. Waldeii (NOAA, 1976).

-"Unjacketed fiber rope of natural or Synthetic fibre have mghy favourable properties but they are highly susceptible to cutting while under tension." -"Biting has been reported as occurring mostly on small lines. However, it appears that mere size does not make a line immune to biting attack. But they can also absorb more, biting than a small line without parting." -"At the present time knowledge of stumming of deep sea mooring lines seems to be in early stage of development. Theoretical cal­ culations indicate that mooring lines of approximately 13 mm (1/2 in) diam. should vibrate at rates which are in a range of maximum attracti­ veness to sharks." -"Sharks appear to be the most serious cause of severe damage to mooring lines. Between 23 North and South latitude sharkbite should always be expected;" Between 23° and 40° North and South latitude, liability to biting will depend upon season (warm water)." -"If a moored station survived 100 days from fishbite, the data indicated that the chance of its lasting for a much longer period of service were very good."

(d) Who Uses the FAD? j:

It is better to reach an accord between the potential users of the FAD sooner rather than later. It could save problems and time. Ideally the FAD should be used in conjunction with artisanal and industrial fishing, especially in developing countries....

(e) Sharks

Sharks are a problem around FAD mainly for the artisanal fisheries, because.often when a fish is hooked there is insufficient time to, pull it aboard before a shark .attack. It is possible; to minimize the problem with an intensive shark-catching programme. - 15 ~

Check if there is a potential market for shark fins or flesh.

VIII CONCLUSION

The potential of the FAD to aggregate tuna species is now well known. In future it is possible that the majority of tuna catches will be made around FAD or other floating objects worldwide.

:': It is'expected that' in the future most countries involved in, tuna •• fishing will have a number of FAD set in areas with proven production* •.

These will be maintained and replaced after loss.

The main'objective bf this paper is to help make a durable model,, anchor it'pr6perly and use it with success. ., s

Following is a brief summary of the main.Recommendationss f

1. make a marketing survey; . , . 2.';. find .4 .good anchoring, location by interviewing1 fishermen; 3. !nia'ke a durable FAD; • ... • . ... 4. ...anchor...it-carefully;; 5. maintain it well; 6. avoid problems between the users; 7. educate the fishermen to use it; 8. keep a record and data for each FAD; 9. learn from good and bad experiences; 10. keep a stock of FAD materials for fast replacements. - 16 -

ACKNOWLEDGEMENT

I wish to express my sincere thanks to Mr Harry Sperling, FAO Regional Fisheries Coordinator, for his technical advice and encouragement during the preparation of this paper. Publications by another FAO Staff Member, MrArild Overa, Naval Architect, relating to his assignment in Western Samoa, were valuable reference material.

Special thanks are due to the staff of the Fiji Fisheries Division, Ministry of Agriculture and Fisheries, who permitted me to participate in the rigging and deployment of their FAD and subsequent fishing operations around them, and to those (Dr Peter Hunt, Dr Tony Lewis, Mr Garry,Preston) who gave me good advice for the drafting of this paper.

Many thanks also to different FAO consultants who visited Fiji, in particular to lit Rupertq A. Gonzales, who came from the Philippines to share his experience in tuna purse seining in conjunction with FAD and Mr Uili O'Brien from Western Samoa with whom I spent many interesting hours learning the techniques of small-boat trolling and handlining around FAD. - 17 -

BIBLIOGRAPHY

Berteaux, H.O. and A. Wiley, Buoy engineering interscience publication. John Wiley & Sons, New York. London-Sydney-Toronto

Blackburn, M., Oceanogr.Mar.Biol.Ann.Rev., (3):299-322 1965

Friedrich, H., Marine Biology. Publication by Sidgwick and Jackson - London

Gonzales, A., FAO Report on technical assistance for skipjack and tuna seining 1981 with the use of anchored bamboo rafts in the Fiji Island

Matsumoto, M.,.K.T. Kazaraa and D.C. Aasted, Anchored fish aggregating 1981 devices in Hawaiian waters. Marine Fisheries Review, Sept. 1981, 49(9)

Murdy, O.E., The commercial harvesting of tuna-attracting payaos: a possible 1980 boom for small-scale fishermen. ICLARM Newsletter, Jan. 1980

Popper, D. and A.L. Philipp, Small-scale pole~and-line fishery in Western 1981 Samoa, FAO Report 1/

Preston, G.L., Small-scale tuna. Fishing Project. FAO-Fiji Fisheries Division 1982

Prindle, B. and R.G. Walden, Deep-sea lines fishbite manual. National Oceanic 1976 and Atmospheric Administration (NOAA). National Data Buoy Office Bay St Louis, Mississippi 39520

Sund, N.P., M. Blackburn and F. Williams, Tunas and their environment in the 1981 Pacific Ocean. Oceanogr.Mar.Biol.Ann.Rev., (19):443-512

1/ D. Popper: FAO Aquaculturist A.L. Philipp: Chief Fisheries Officer These catamarans are constructed in Western Samoa under the name "alia", and have been successfully tested in fishing at and near FA.D. They can be used for hand lining ( bottom and midwater), trolling and small-scale pole -and -line fishing .

Profile

Water spray Bait tanks Trolling booms (2) (2)

VU==:

Fishing reels Stern ra (4)

CATAMARAN FOR LINE FISHING FOR LARGE PELAGIC FISH Raft

SETTING THE F.A.D. 5m long (or 10m doubled ) synthetic straps, coconut fronds, E old fishing netting straps,etc. in 025 mm galv.pipe

0 7mm chain E O CM I IT)

PPrope 0 10-18 mm

Chain sinkers

APPENDAGES litres

3x250 litres drums model

IT I Safety chain shackles with bolts and nuts and safety pin

Light

((\)) Radar reflector \w

r=^ ^ ^ 0 10mm stainless steel U-bolt ^

H_ 400 mm m, 11 mi TET 0 13mm stainless Plastic foam " steel U-bolt

1.5 m 3 m

THE RAFT Theoretical Practical

Sea level

Swivel Swivel

400 m 2 coils of 220 m

200 m

Swivel V Swivel 2 Swivel V-/" Swivel 2 3 \ 3 / Chain Chain

o If possible in o one length o Polypropylene (PP) rope

800 m

Polypropylene ( PP)rope

•*fe3^-

ANCHORING SCOPE ( Not to scale ) 50 mm

0 20mm steel rebars

250 litres drum filled with concrete

L-steel bar

ANCHORS 014mm chain

All 8 corners are reinforced with chicken wire netting of 0 5mm mesh

CONCRETE ANCHORS Light

Rador reflector

Appendages ( Polypropylene strap band attached to a rope net)

t> 16 mm shackles

014mm chain

0 16 mm shackles

Approx. scope 1.4 '. I ratio = RAD. DESIGN