A REVIEW OF ARTIFICIAL REEFS DEVELOPMENT AND USE OF FISH AGGREGATING DEVICES (FADs) IN THE ASEAN REGION

BY

MEDINA N. DELMENDO'

1. INTRODUCTION

The development of artificial reefs in ASEAN countries is of recent occurrence as a consequence of the felt need to enhance fishery resources due to overfishing.

The State of fishery resources in Southeast Asia has been assessed by Chikuni (1988). He reported that the major species groups, the pelagic and demersal fish resources have generally declined or remained stagnant as a result of continuous overfishing of the major fish stocks. There is excess fishing intensity in most countries, reduction of which remains a complicated social issue particularly in the municipal or artisanal fishing sector.

No further increases in the major exploited fish stocks could be expected unless resource enhancement or rehabilitation measures are employed. One of the approaches towards resource management is the deployment of artificial reefs.

Artificial reefs (ARs) and fish aggregating devices (FADs) both work on the same principle of attracting fish. Both are artificial habitats. The former is a submerged FAD while the latter is a floating FAD which may be a shallow water or deep water FAD such as the "payaw" used in the Philippines. 4Rs may also be submerged in water depths of 5 to 30 m.

The ASEANIUNDPIFAO Regional Small-Scale Coastal Fisheries Development Project, RASl841016, organized a regional Workshop on Artificial Reefs Development and Management, as one of the Project activities in 1988. The Workshop was aimed at assessing the state of knowledge on development and management of ARs, exchanging experiences, identifying constraints and determining a cooperative plan of action in the region to enhance coastal fishery resources.

This paper reviews the state of development of artificial reefs in the ASEAN region and presents the experiences gained by the member countries on the use of ARs and FADs.

2. HISTORICAL DEVELOPMENT OF ARs AND FADs IN ASEAN

Improved designs of artificial reefs developed in the region only recently. Traditionally, fishermen have employed such devices for sustenance fishing using floating aquatic plants or submerged brush piles.

'! Project Coordinator, RAS/84/016, ASEANIUNDPIFAO Regional Small-Scale Coastal Fisheries Development Project, 3rd Flr., Arcadia Bldg., 860 Quezon Avenue, Quezon City, Metro Manila, Philippines.

In Malaysia, it was reported (Hung, 1988) that the use of artificial reefs by traditional fishermen in the east coast of Peninsular Malaysia dates back to the early 1900s. This was practiced by sinking derelict wooden boats, bundles of tree branches, twigs and rocks.

The serious decline of fish catches in the coastal waters of Peninsular Malaysia from 131.1 kgs to 58.9 kgs/hr during the 1970-80 decade prompted the government to take steps to enhance the demersal fishery resource. In May 1975, the first artificial reef was estabished at Pulau Telor, Kedah. The programme of artificial reef development was ad hoc in nature to begin with. It gradually expanded towards 1985 when a total of 14 artificial reefs were installed in various locations.

The encouraging results observed on ecological development around the artificial reefs convinced the government that fishery resources could be improved by the use of artificial reefs. Thus, a comprehensive programme of reefs construction was undertaken by the government. From 1975 to 1987 a total of 52 tyre reefs were emplaced in the east and west coasts of Malaysia. Besides tyre reefs the government also sank derelict or confiscated fishing vessels with a total of 77 units from 1984-1987. Concrete pyramidal artificial reefs consisting of 204 units were also emplaced from 1986-1987. The distribution of artificial reefs emplaced from 1975 to 1987 is shown in Figures 1 and 2 wherein Peninsular Malaysia has the greatest number of ARs. The government allocated a budget of M$8.24 million (USS3.3 million) in the Fifth Malaysia Plan, 1986-1990.

The main objective of artificial reef development is to enhance marine fishery resources. As such, fishing in the sites are prohibited.

t

81 PENlNSULAR MALAYSIA

SARAWAK

SABAH

1975 1977 1979 1981 1983 1985 1987

Year

Figure 1. Development of artificial reefs in Malaysia by number of reef.

Source: Hung, Edward Wong Fai, 1988

2.2 Philippines

Like in Malaysia, the concept of using artificial reefs is not entirely new. Subsistence fishermen pile tree branches and twigs in estuaries to attract fish into them (Miclat, 1988). In rivers and lakes, brush shelters made of tree branches or aquatic weeds, both floating and submerged are used on the same principle. These artificial habitats also serve as spawning and nursery areas for some species.

The state of coastal fishery resources of the Philippines has also declined avet the years. It has been reported that the -major demersal and pelagic stocks are already heavily fished (Chikuni, 1988). Fishing units and effort have increased which consequently led to the overfishing of these resources. The need for resource enhancement measures prompted the government to adopt ARs as a management tool. However, unlike Malaysia, the .Philippines use the ARs and FADS as accessories to fishing. Fishermen are allowed to fish in the AR sites. FADS are used for tuna fishing.

The development of artificial reefs in the country started in 1977 in an experimental project of the Silliman University. The Marine Science Institute of the University of the Philippines also constructed an AR in 1978. The Bureau of Fisheries and Aquatic Resources collaborated with the academic institutions in this effort. From 1979 to 1981, the BFAR, in cooperation with other government agencies and civic organizations, loined hands in the establishment of ARs. During the period, 7 units were emplaced. In 1982, a combination of artificial tyre reef and fish aggregating device, "payaw" (FAD) was developed. The use of "payaw" is discussed in more detail in Section 6.

The position indicative results of these experimental project led to the launching of a 4-year nationwide AR development programme (ARDP) beginning in 1985 under the financial support of the Ministry of Human Settlements and technical guidance of the BFAR (Miclat, 1988). The PFDA-SBATI reported a total of 8 099 bamboo and ipil-ipil reef modules emplaced in four provinces from 1984-1985. Figure 3 shows the geographic distribution of ARs in the Philippines. The expansion of artificial reef development from 1977-1987 is illustrated in Figure 4.

In a related devel~pmurtt, a regional project, the Central Visayas Regional Project-1 (CVRP) funded by the IBRD under Loan No. 2360-PH was implemented in 1984. This is an integrated rural development project with a nearshore fisheries sub-component. From 1984-1988 the project developed a total of 13 500 bamboo reef modules for 270 family clusters along a coastline of 30 km (Aprieto, 1988). The CVRP- 1 is funded under a loan of US$35 million over a 5-year period of which about 10% is allocated for five nearshore fisheries sites encompassing 210 km of coastline in four provinces of the region.

At present the government is implementing a more vigorous AR development programme under the Department of Agriculture funding for which would most likely come from external assistance such as the recent loan from the AsDB. A total amount of US$33 M is intended for coastal zone management in which AR development for resource enhancement is a component. The purpose is to provide small-scale fishermen with better income from fishing with the aid of artificial reefs. Implementation of this programme has been approved by the government.

2.3 Thailand

The development of ARs in Thailand started in 1978. As of 1988 the government emplaced a total of 34 ARs in nine provinces (Sungthong, 1988). In the sixth National Economic and Social Development Plan, 1987-1991, the government's AR development programme will cost about Bht 200 million (US$7.7 million). The Plan envisions construction of several units of concrete ARs to be distributed in a total of 22 provinces along the coast particularly in the southern part of the country. It is projected that six ARs per year will be constructed for selected sites in these areas. The Plan consists of two programmes, namely; the Rural Area Development Programme and the Natural Resources and Environmental Programme. The first programme is to raise the standard of living of small-scale

ARTIFICIAL REEFS

0 TYRE REEFS 0 DOAT REEFS A CONC~ETC REEFS

Figure 2. Location of artincia1 reefs in Peninsular Malaysia.

119

SAN NT;OLAS SHOAL

Figure 3. Sites of the BFAR artificial reef' development programme (ARDP).

Source: Miclat, R, (1988)

YEAR

Figure 4. Progress d artificial reef building activity in the Philippines.

-

Source: Miclat, R., 1988

fishermen and the second is to rehabilitate coastal water resources. The ARs developed for the small-scale fishing villages were supposed to be seeded with fish seed to enhance coastal fishery resources (Pramokchutima and Vadhanakul. 1987). They were also meant to prevent trawlers from fishing in nearshore waters so that the small-scale fishermen would not be deprived of their livelihood, thus prokiding a resolution of conflict with the commercial fishermen.

2.4 Singapore

Singapore is a country built up on coastal land reclamation which started in the 1960s. Such reclamation still continues to this day which will eventually add more than 10% of the original land area. to the country. As a consequence of the economic development needs of Singapore, the extensive reefs in its southern coast of the mainland have been destroyed by land reclamation to give room for urban uses and port development. The fishery resources for subsistence fishing and recreation have also diminished (Hsu and Ling, 1988).

The development of ARs in Singapore is to restore aquatic resources in the already disturbed marine environments and promote recreation and tourism. This was initiated only in 1986 under the ASEAN-US Coastal Resources Management Project (CRMP) being implemented by ICLARM. The project is funded by the USAID with US$225 000 and a counterpart support of US$227,500 from the government.

To date, seven sites have been identified and surveyed for emplacement of ARs. So far, the site selected at Terumbu Pempang Tengah North has been approved for demonstration of ARs. Other sites are awaiting approval from the Port of Singapore Authority (PSA) and Planning Department. The plans and types of ARs to be used have been made and the plan of maintenance, operation and monitoring has been established. The PSA had sunk condemned wooden lighters east of Terumbu Pempang Tengah which was a cheapest mode of disposal. These already serve as artificial reefs which the government will monitor as part of their CRMP.

Based on the results of this project, more sites for the development of ARs in Singapore will be identified.

2.5 Indonesia

The government has not gone into massive AR development activities of the same magnitude as her ASEAN neighbours. However, it is doing some work towards rehabilitation of damaged coral reefs by transplantation. Preliminary results indicated that transplanted corals using concrete boxes grew fast. This could be a less expensive approach to habitat improvement to enhance fishery resources.

Small experimental artificial reefs were undertaken in Pari Island at 3-4 m depth of water. The reef measured 1.2x0.7x0.7 m. Ten species of fish were found in the reef, three species of which were found more frequent than others (Lutianus, Caesio and Lethrinus). No extensive AR development is taking place in the country but the use of "payaw" (FAD) for tuna fishing is already widely practiced.

Artificial reefs made of discarded tricycles and buses have been used since 1988. This is part of the plan of the government to t-xminate the use of tricycles in Jakarta by 1992 (Hardjono, 1990).

2.6 Brunei

This country is not hard pressed in regard to the state of fishery resources as the other ASEAN countries. For one thing, fishing is not a major source of livelihood and there are not many fishermen competing for the marine fishery resources. The need for the development of ARs in Brunei's coastal waters is therefore not as strong as the need of her ASEAN neighbours. However, the country is conscious of coastal resources management. The government is participating in the ASEAN-USAID

Coastal Resources Management Project being executed by ICLARM in which the government hopes to develop and strengthen its fishery institutional framework to become more prepared to implement fishery management programmes in the medium- and long-term future.

3. MATERIALS USED, DESIGNS AND PATTERNS OF INSTALLATION OF ARs

3.1 Materials used

The most common material used for the construction of ARs comprises old tyres of motor vehicles. This is waste material which is cheap and available in most countries. The non steel-belted tyres is preferred by Singapore as some studies showed that the steel-belted tyres frayed after corrosion had set in which reduced the surface area for attachment of organisms in the reef. On the other hand, Malaysia observed that these tyres remained in good condition for over four years. A more thorough observation in this regard appears necessary so as not to litter the seabed with undesirable waste materials.

A combination of tyres and bamboo ARs are used in the Philippines. The bamboo is abundant and more easily avilable than used tyres in rural areas.

Other materials used for the construction of ARs are concrete cylindrical and culvert cement pipes, concrete rings and rubber wood are also used. The advantages and disadvantages of using these materials are summarized as follow:

Materials used Advantage Disadvantages

Tyres

Concrete blocks

Concrete rings

Light weight Convenient to install

Moderate life span

Low sinking rate

Good habitat and shelter for marine fauna

Easy to install

Life span 10 years

Accurate set up position Good habitat and shelter

Suitable for hard bottom

Moderate weight

Easily purchased

- - - -

90% weight loss in water Need joint materials that do not easily deteriorate

Easily damaged by mecha- nized fishing gears

Difficult set up positions

High cost

4O0I0 weight loss in water

Difficult to transport

High cost

Not suitable for soft bottom

Easily damaged by mechanized fishing gears

Easily damaged during set up

.../. .

Materials used Advantages Disadvantages

Accurate set up positions

Reinforced concrete pipes Easy to purchase Moderate weight

Stones

Rubber wood

Convenient to transport

Good shelter and habitat

Accurate set up positions

Durable

Low cost

Accurate set up positions

More durable

Easy to purchase

Difficult to install High sinking rate Unsuitable habitat and shelter

High sinking rate High cost

Better with heavy weight pipes

High sinking rate

Difficult to install

Difficult to transport

Need durable joint materials

Easy to set up Easily damaged

Good for pelagic fish Source: Sinanuwong, 1988.

3.2 Designs of ARs

Usually, ARs are designed in pyramidal structures of varying sizes. This is true with used tyre reefs, combination of tyres and "payaw" and concrete ARs. Concrete blocks are also used in pyramidal design.

In Malaysia, the size of tyre ARs ranged from a minimum of 300 to over to 50,000 tyres per reef. The Philippines uses the low relief tyre units and the high relief tyre modules. A tyre unit is a triangular or inverted conical shape made up of 4 tyres (Figure 5) while the tyre module is the pyramidal shape made up of 8 tyre units or 32 pieces of tyres (Figure 6). Malaysia has so far used a total of 505 466 tyres for a total number of 65 artificial reefs (Figure 7).

Bamboo reefs are weighted with rocks wrapped in sacks and tied to the reef to keep them submerged ( Figure 8). The fish aggregating' device, "payaw" (FAD) is also being used in combination with tyre and bamboo ARs (Figure 9).

Concrete ARs used in Malaysia and Thailand are also constructed following a pyramidal shape. Malaysia has the most extensive concrete ARs mounted on Chengal hardwood base as shown in Figures 10 and 11. Thailand uses concrete cylinders put together by grappling iron (Figure 12). They also use a combination of tyre reefs and concrete blocks installed in various patterns. The government experimented with a total of 30 designs of ARs (Figure 13) emplaced in different patterns.

Figure 5. Tyre unit.

Source: Miclat, R.I., 1988

Fignre 6. Tyre module.

Source: Milat, R.I., 1988

Figure 7. Development of artificial reefs in Malaysia by total number of tyres.

Source: Hung, Edward Wong Fai, 1988.

Figure 8. A benthic artificial .reef used in the Philippines.

Source: Aprieto, 1988.

Figure 9. Diagrammatic representation of the tyre-bamboo artificial reef combination with two "payaws".

Soup: BFAR, 1984.

3.3 Patterns of installittion

A tyre reef module may have a base area of 3 m2 with a height of 2 m. ~ndividuaf modules are installed by threading them through a polyethelene rope which serve as the shot-rope whereby the pyramids slide down to the seabed. The end of the shot-rope is tied to the last pyramid before it is sunk (Figure 14) as practiced in Malaysia. In the case of concrete ARs, these are installed individually with the use of cranes as these are massive and heavy.

The tyre and bamboo ARs could be installed with the use of rafts as practiced in the Philippines. The rafts are towed by motorized fishing boats to the sites and the ARs are individually sunk. The Philippines has not gone into using massive concrete ARs; the government promoted the use of a combination of tyre and bamboo reefs in selected sites. Recently, the use of these combinations with "payaw" has become quite popular.

Thailand is perhaps the only country in ASEAN that had tried a variety of patterns and combination of ARs (Figures 15a-b). Due to inadequate experience in the design and construction of ARs, all the reefs installed disappeared after a year. The experience gained was, however, found useful in that the ARs prevented the operation of trawlers and push netters from fishing in the reef sites thereby benefitting the gill net fishermen.

CHENGAL HARDWOOD

V

WOODEN PLATFORM

Figure 10. Concrete pyramid (pip@.

Source: Hung, Edward Wong Fai, 1988.

8 PCS BOLT

2"THICK (BRC lo)

CONCRETE PIPE UNIT

CHENGAL HARDWOOD F

WOODEN PLATFORM

Figure 11. Ten pieces cylindrical

STEEL CABLE .N8"

concrete pipedpyramid.

Source: Hung, Edward Wong Fai, 1988.

Figrue 12. Dimension and set of concrete cylinders for artificial reef.

-

Source: Sinanuwong, Khian, 1988.

TYPE 1

TYPE. 6

TYPE 10

m TYPE 1 4

m TYPE 18

TYPE 22 - TYPE 26

TYPE 2 TYPE 3 TYPE 4 TYPE S

TYPE 15

@ TYPE 16

TYPE 17

TYPE 23

c e 3 TYPE 30

TYPE 29 1

Figure 13. Models and materials of artificial reef installation in Rayong area.

Source: Sungthong, Santi, 1988.

Figure 14. Emplacement of tyre-pyramids at reef !site.

-

Source: Hung, Edward Wong Fai, 1988.

.4. COST OF CONSTRUCTION OF ARs

The cost of construction of ARs depends on the, type of materials used and the size of the reef. Prices of construction materials also vary from country to country and even within a country.

A bamboo reef module used in the Philippines costs about P 400 or about US$20. One reef placement with an area of 400 m2 could have 64 modules; the size per module is 6 m3 or 2 mx2 mx1.5 m. On the other hand, a concrete reef module of .I14 m3 costs f 840 (USS42). A reef area of 400 m3 could contain 49 modules. Concrete ARs in Malaysia costs from MS6 000 (US$2,400) to M$7,600 (US$3,040) per unit. These are massive cylindrical cement blocks arranged in pyramidal shape on hardwood platform. A unit of this type of AR weighs 1.5 tons. The cost of deployment is substantial as this involves the use of heavy equipment for transport and launching at the sites. About M$20,000 (US$8,000) is required for t-ansport from port to site of launching. It was reported that the cost of transporting this type of AR made up 60% of the total cost of the AR (Rajuddin and Latun, 1988) in MaIaysia .

I MILL I , I MILL

I ULE I 1

0 SETS OF CONCRETE CYUNOERS

AREA 2 - 2 SETS ff CONCRETE CYLINDERS

Figure 15a. Pattern and arrangement of artiftcfal reef ccmstruction.

% TIRE

0 CONCRETE RZNG

Figure 15b. Pattern and materials of artificial reef in haila and:

Source: Songthong, Santi, 1988.

5. EFFECTS OF ARs ON FISHERY RESOURCES

Preliminary estimates made on the effect of ARs on fishery resources in Malaysia indicated that within four months after emplacement the ARs were colonized by various species of fish such as snappers, groupers, fusiliers, rabbitfishes, parrotfish, damselfish and squids as well as cuttlefish. A stable composition and density of fish population was achieved within a year. Hung (1988) reported that a population level of grouper at 10 kg/m3 of AR is a reasonable estimate. Large shoals of snappers, Lutianus sp. with an estimate number of 10,000-15,000 and fusiliers, Caesio sp. numbering about 10,000 were not uncommon in the ARs. Fishermen reported catches of 1.09 kglhr by hook and line while a fish trap could catch 4.65 kgltraplweek consisting mainly of groupers within the AR sites. No data on sizes of fish caught were given.

Experience in the Philippines also indicated that within 3-4 months of emplacement of ARs, various species populate them. A case study conducted on a 254 sq m bamboo AR showed that 88 species of fish of which 46 species consisted of high quality fish of commercial value colonized the AR (Miclat, 1988). A 4-month fishing operation using gill net, hook and line and spear yielded 963.4 kg valued at ? 11264.70 (US$563.24). The catchlmonth was equivalent to 280 kgs. The cost of this AR was ? 1261.00 (US$63). In a 1000 sq m tyre AR, 112 species of fish were recorded of which 41 species were of high commercial value. A total catch of 804.5 kgs were reported in 13 months of fishing valued at P

24 000 (US$1,200). The catch per month was 61.85 kgs. The cost of this AR was f 18,000 (US$900). In both observations the size composition of fish catches was not determined and neither was there any observation of fish catches outside the reef area.

The development of artificial reefs in most of the countries did not have the benefit of scientific criteria to assess productivity and the effects of ARs on fishery resources. One thing definite however, is that ARs are effective in aggregating fish. What contribution the ARs give in terms of increased fishery production over time is not known neither is there information on impact of ARs on the socio-economic conditions qf coastal fishermen.

It would be useful to look at the findings of Singapore in its AR development programme. Observations have been made in fish, transects at selected AR sites prior to installation of the reefs. The physico-chemical parameters 'of the waters at the selected sites have likewise been observed and compared. These observations are essential in determining the final composition of life forms in the various sites after the ARs have been emplaced.

In Thailand, it was reported that prior to AR development the threadfin fishery in certain coastal areas in the southern part of the country was available to the small-scale fishermen only for about 15 days on account of the intrusion of trawlers and push nets in the area during the season. The average catch per fishing trip of gill net fishermen was 4.71 kg. After the ARs were installed, the trawlers and push netters could not fish in the area. As a consequence, the threadfin fishery became available to the small-scale fishermen for over six months and their average catch increased to 8.33 kdfishing trip. This could be a mere shift of available resource from the trawlers to the gill net fishermen rather than increase in resource productivity.

The ARs were installed in an area of 4x1 mile located 2 miles from the shoreline. The water depth of the site was 4-5 m. There were 205 sets of concrete cylinders with a dimension of 10Ox50x5 cm each (Sinanuwong, 1988).

This experience demonstrated that the ARs serve as a deterrent to trawl and push net fishing operations in shallow coastal waters, thus resolving the conflict between the commercial and small-scale fishermen. The competition for fishing was eliminated in favor of the latter by the use of ARs. An assessment of the impact of the ARs on resource enhancement is still necessary.

6. FISH AGGREGATING DEVICE (FAD) AND IT5 IMPACT ON FISHERIES

Bamboo fish aggregating device locally called the "payaw" in the Philippines is used for fishing small pelagic species such as mackerels, roundscads, sardines and tunas. Figure 16 shows the extent of "payaw" fishing areas in the Philippines (Guerrero, 1988).

6.1 Impact on tuna production

The impact of "payaw" in Philippine tuna fishing is significant. In 1971 tuna production was less than 10,000 mt. With the advent of the "payaw" in 1976, production increased to 125,000 mt and a peak production of 266,111 mt in 1986 which comprised 20% of the national fish catch in that year. On account of the "payaw" the Philippines was able to get a share in the tuna export market (Aprieto, 1988). It was the largest fishery export until farmed penaeid shrimp took over in recent years.

In South Cotabato alone, there are 33 units of purse seiners ranging from 40-100 Gross Tons operating in the Moro Gulf and Davao Gulf. Each of these boats has an average of 25 units of "payaws" installed in water depths ranging from 1,000-2,000 fathoms. Each "payaw" costs about F 50,000. Aside from the purse seiners, there are 70 ring netters with an average of 20 units of "payaw" each or a total of 1,400 FADs. In this area, therefore, there is a total of 2,225 units of FADs with a total investment of P 111.25 million excluding fishing vessels.

"Payaw" fishing areas 1. Lingayen Gulf 2. Manila Bay

Payao fishing , grounds

3. Batagas Coast 4. Tayabas Bay 5 . %est Palawan Water 6. Cuyo Pass 7. West Sulu Sea 8. South Sulu Sea 9. East Sulu Sea

10. Moro Gulf 11. Davao Gulf 12. Bohol Sea 13. Leyte Gulf 14. Camotes Sea 15. Visayan Sea 16. Guimaras Strait 17. Sibuyan Sea 18. Ragay Gulf 19. Samar Sea 20. Lagonoy Gulf 21. Lamon Bay 22. Casiguran Sound 23. Palanan Bay 24. Babuyan Channel

CEL,EBES SEA

Figure 16. Map of the Philippines showing "payaw" areas (shaded).

Source: Guerrero, C.V., 1988.

6.2 Socio-economic impact

The "payaw" is an accessory to fishing with ring nets, purse seines and handlines in which the small-scale and commercial fishermen find compatibility. The ring netters or purse seiners catch the smaller sized school of tunas that aggregate at the surface while the large tunas are caught by handlines by small-scale fishermen using small pump boats.

Some small-scale fishermen pool their resources together to assemble a "payaw" and install this in their chosen site. A fishing boat operator with purse seine or ring net is contracted to haul the fish from their "payaw" and share 25% of the total catch in cash or in kind. The ring net or purse seine operator gets 75%. The small-scale fishermen are assured of their income.

Small-scale fishermen who do not own "payaw" but engaged in handline fishing in "payaw" were found to earn an average of P 20,684 in about seven months of fishing season in northern Luzon. This is very much higher than the average income of municipal fishermen at F 5,000 - i 10,000lyeat without "payaw" (Guerrero, 1988). Their fishing time is also shortened as they do not scout around to look for fishing grounds. The "payaws" are certain to have fish below them particularly when they have been in place for at least three weeks.

6.3 Impact on stock structure and biomass

The "payaws" have been so effective in aggregating fish that even the juvenile stocks of tunas and other pelagic species are piobably being unnecessarily harvested. It was reported that 90% of yellowfin and skipjack tunas landed are less than one year old. As a result of dense aggregation of juveniles in the surface layer of water immediately below the "payaws" heavy predation also occurs. Stomach content analysis of adult yellowfin showed that 70% of their food consisted of young skipjack and yellowfin tunas. This situation is no longer considered natural mortality but a consequence of fishing (Aprieto, 1988). It is obvious that juvenile tunas are being caught more on account of the FADS. Whether this is a "boon or a bane" in resgect of the tuna fishery in the Philippines is something that needs a serious analysis. Regulation of the number of "payaw" should be imposed and that fishing with this device during the peak spawning period of tunas should be controlled.

Observations made in artificial reefs in Thailand showed that several species of fish (31 species) were attracted to the ARs. Catches made by using fish traps, showed very small size of fish. For instance, the species Siganus javius consisting of 4,464 individuals weighed only 216.12 kg or an average of 0.048 kg per fish: Epinephelus tauvina consisting of 11 pieces had a total weight of 1.13 kg or an average weight of 0.102 kg each. From the fish trapping operations done from August to November 1984, a total of 5 766 fishes were caught with a total weight of 307.32 kg or an average of 0.053 kg each. This size of fish is quite small for any species to be caught particularly of species of high commercial value such as the groupers. Similar observations conducted in the same reef from March to June 1985 showed the same sizes of fish with an average weight of 0.059 kg each.

The above structure of fish stocks found in artificial reefs demonstrated that they indeed attract juvenile fish. This might be due to the fact that the artificial reefs were located in shallow water of 5-6 m deep located about 400 m from the shoreline.

Observations made in other artificial reefs ihstalled in deeper waters, 7-18 m and 2,500 m to 4,500 m away from the shoreline indicated several species of fish as well. Species found were dominated by Epinephelus sp; Lethrinus spp; Lutianus spp and Scolopsis sp which are mostly high value species. Unfortunately, data available showed total weight of fish only but did not provide information on the number of individuals caught to compare the stock structure with those found in shallow artificial reefs:

Fish catches obtained in the surrounding area of the reef showed similar species coinposition but the size of fish was much smaller, averaging only 0.030 kg. There were more fish caught within the reef than outside; species diversity was also greater within the reef.

Alcala and Luchavez (1988) observed that a small AR of 24 m3 produced and attracted at least the same biomass of fish that was harvested or about 6.9 kg/m3. Barretto and Miclat (1988) observed that a 254 m2 AR yielded a total catch of 441.7 kgs during 87 fishing operations using gill net, hook and line and spear gun for the period March-May 1985. This was equivalent to an average catch of 5.07 kglfishing operation. No data on the number of fish caught were given although the species composition was 63.5% Sphyraenids and 36.5% Leognathids.

Barretto and Miclat (1988) found that recruits to the ARs were mostly juveniles and that 52% were visitors, 18% transients and 30% residents. Competition for space and predation were reported to be the mechanism which regulate persistence of initial recruits and further recruitment of possible residents. Constant gains and losses of species found in the ARs were observed among the visitors; there was minimal variation of species composition of the residents.

Studies conducted on artificial reefs in Hawaii, (Moffit, 1987) indicated that the depth of artificial reefs is more important than the reefs structural design or material in determining the aggregated biomass of fish species. Transient species aggregate around ARs very quickly. Two deep reefs of different design, volume and structural material were found to have similar community composition, diversity and biomass of aggregated transient species which varied between 50 to 350 kg exhibiting similar trends over time at two sites (5.6 m3 for concrete reef and 139 m3 for the fiberglass-reinforced plastic reef). The shallower concrete reef maintained an aggregate biomass of less than 10 kg in a reef volume of 5.0 m3.

On the other hand, the diversity of resident species started from zero and increased over time at all reef sites with higher rates of increase in the shallower concrete reef, although the biomass of resident species was much lesser than the transient species. The study indicated that deep water artificial reefs work primarily for aggregating fish rather than increasing fish production. The vertical relief and volume of artificial reefs are not important in aggregating transient species.

There is still much research work to be done in order to determine the quantitative and qualitative contribution of artificial reefs in resource enhancement. Most observations have shown that ARs are effective in aggregating various species in them which makes fishing much easier for fishermen. Indiscriminate use of ARs for fishing purposes may have to be looked at with concern for the time being until concrete evidence in general for increased production emanating from ARs becomes available.

It is widely known that Japan has the most extensive artificial reef development programme which started in the early 1950s. At present a total of 6,400 artificial reefs have been installed over an area of 1,801 km2 within 200 m depth (Yamane, 1987).

Artificial reefs are part of the government programmes in Japan for creation and development of coastal fishing grounds. Any artificial reef project should feature a nursery, rearing and spawning reefs to be installed in a coastal area. The idea is to provide restocked fish seed to proceed from one reef to another and finally end up at the fishing reef. Despite 30 years of experience and research on ARs, there are yet no clear conclusions which could be drawn from their research. However, better results are anticipated in the coming years, particularly through international cooperation (Thierry, 1988).

7. CONCLUSION

Most ASEAN countries have gone in a big way for development of ARs as a means to rehabilitate or enhance coastal fishery resources. However, experiences in the countries showed that the development of ARs were initiated without the benefit of establishing the necessary baseline data to facilitate assessment of the impact on fishery resources and fishery production on account of the ARs. The use of the "payaw" (FAD) in the Philippines was responsible for the increase in tuna production. However, the impact on Philippine tuna resource is something that has yet to be ascertained.

While a large number of ARs of different sizes and designs have been developed and emplaced, very little monitoring work of a quantitative nature has been undertaken. It is, therefore, difficult at this stage to determine the resource enhancement benefit from ARs other than their efficacy in aggregating various species.

Juveniles of various species are no doubt the main groups of individuals attracted to the reefs and the FADs. Very little data exist in this regard but from what is available, fish catches obtained from ARs (in Thailand) showed the predominance of juveniles. Even for the "payaw" (FAD) in the Phiiippines, tuna catches were reported to consist mainly of juvenile stocks. In this connection, attraction and production in ARs should be taken in a different context if their use for resource enhancement is the main objective of AR development. The policy of the government of Malaysia not to allow fishing within the AR, therefore, appears justified. On the other hand, ARs for fishing in shallow coastal waters such as those promoted in the Philippines would perhaps require some rationalization before further deterioration of coastal fisheries comes about as a result of proliferation of ARs. There is an apparent need to classify ARs for fishing and for resource enhancement purposes in view of the positive indications that attraction of juveniles is predominant in the ARs and FADs. There is, consequently, a need for regulations and control to promote resource enhancement and increased fish production.

Without an accompanying regulatory measure, the proliferation of artificial habitats would be contributing to an accelerated depletion of fishery resources as these structures have been effective in aggregating young stocks. Their rapid removal is inevitable due to the high catchability afforded by the ARs.

While the objective of artificial reef development is common in the region, the approaches made are quite diverse. For instance, in the Philippines, ARs are considered fishing gears like fish traps and the government encourages the private sector to assist and promote the AR development for the benefit of small-scale fishermen to increase fish catches and their income. The programme has a very attractive socio-economic appeal to administrators. On the other hand, there is very inadequate technical and economic feasibility information available pointing to increases in fishery production in general. In Thailand, the ARs are also used to prevent commercial fishing activities in areas where small-scale fishermen also operate. Monitoring of these activities have not been systematically carried out to obtain quantitative and qualitative evidence of resource enhancement and increased fishery production.

In the light of this information and experiences, the workshop on Artificial Reefs Development and Management, 13-18 September 1988, sponsored by the ASEANIUNDPIFAO Regional Small-Scale Coastal Fisheries Development Project, recommended cooperation among ASEAN countries in carrying out systematic baseline studies for future artificial reefs development programmes. Such studies should include biological, ecological, oceanographic, socio-economic, engineering and gear technology aspects.

The workshop also recommended that a uniform methodology for monitoring the impact of artificial habitats on fishery resources and production should be adopted in the region for better comparability of results.

A need was felt to distinguish the functions of various artificial reefs and fish aggregating devices as resource management tools. Regulatory measures should be taken into account in order to achieve the objective of resource enhancement with the use of ARs and FADs.

Comprehensive regional evaluation and research on the biological and socio-economic impact of artificial habitats is obviously required to obtain the desired information for policy decision-making on fisheries development and resource management. This would save scarce resources in ASQAN and provide appropriate scientific know-how on the value of ARslFADs in resource enhancement and increasing fishery production.

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