WORKING PAPER SERIES

FISHERIES STOCK ASSESSMENT TITLE XII Collaborative Research Support Program

Fisheries Stock Assessment CRSP Managemea-t Office International Programs, College of AgrIculture The University of Maryland, College Park, Maryland 20742 In cooperation with the United States Agency for International Development (Grant No. DAN-4146-G.SS.5071-00) the Fisheries Stock Assessment CRSP Involves the following participating institutions:

The University of Maryland-Center for Environmental and Estuarine Studies The University of Rhode Island-International Center for Marine Resource Development The University of Washington-Center for Quantitative Sciences The University of Costa Rica-Centro de Investigaci6n en Cienclas del Mar y LImnologia The University of the Philippines-Marine Science Institute (Diliman)-College of Fish­ eries (Visayas)

In collaboration with The University of Delaware; The University of Maryland-College of Business aad Management; The University of Miami; and The International Center for Living Aquatic Resources Management (ICLARM). N -\ w-4'

WORKING PAPER SERIES

Working Paper 79 Destructive Coral neef Fishing: Seeking Perspectives by J.W. McManus, C.L. Nanol&, and R.P. Reyes, Jr. The University of Rhode Ildand

March 1991

Fisheries Stock Assessment Title XII Collaborative Research Support Program

The Fisheries Stock Assessment CRSP (sponsored in part by USAID Grant No. DAN-4146-G-SS-5071-00) is intended to support collaborative research between U.S. and developing countries' universities and institutions on fisheries stock assessment and management strategies. This Working Paper has been produced by The University of Rhode Island research component in collaboration with the University of the Philippines and in association with the International Center for Living Aauatic Resources Management. Additional copies are also available from:

Interrational Center for Marine Resource Development The University of Rhode Island 126 Woodward Hall Kingston, Rhode Island 02881 ABSTRACT Blast fishing, cyanide fishing, and anchor damage were

investigated on a heavily exploited fringing reef in Bolinao, Philippines from 1986-1990. A simple balance shk.et model was used to contrast potential rates of damage with estimateis of coral regrowth. Blasting rates prior to 1990 were 10/hr (± 1.4 90% CI, n=93) withi.n a radius of 1 to 3 km. Damage from blasting may be comparable to that from anchor damage from

fishing boats (0.5 - 1 boat/kin 2/day). Either factor could account for approximately 1/2 of potential regrowth each year, reducing system resilience to other stresses. Best and worst case scenarios indicate considerable uncertainty because of compounding errors. Cyanide was used by 20-80 local fishernen to collect food and aquarium fish. Effects on the reef were difficult to evaluate because of scarce literature on coral mortality from cyanide exposure. Enforcement has effectively limited blasting throughout much of 1990, but there are signs of recurrence. Destructive fishing has yet to achieve village-level unacceptability. INTRODUCTION Destructive fishing is conmon in coral reef areas where population and economic pressures lead to a state of desperate competitiveness among coastal viilagers. A symptom of "Malthusian overfishing" (Pauly 1988), it is a problem which is growing rapidly as human populations grow in coastal developing countries. Two common forms of destructive fishing are blast and cyanide fishing. Anchor damage constitutes a more widespread problem associated with a variety of reef fishing methods. Certain destructive fishing practices, such as muro-ami and kayakas (drive-in net) fishing (Carpenter and Alcala 1977) tend tc be regional in nature and do not yet appear to be spreading rapidly beyond the confines of eastern Southeast Asia. Other destructive effects of fishing, such as damage to corals from nets and traps, are less well-studied. This paper is concerned with attempts to gain a perspective on the relative importance of blast fishing, cyanide use, and anchor damage on a fringing reef which is subject to Malthusian overfishing, and may be typical of the situation to be expected along many of the fringing reefs of developing countries in the next few decades.

The problem may be stated as follows: Given reasonable estimates of the intensity of each activity on a reef, is it possible to estimate the rate of damage to corals, accounting for potential regrowth?

-1­ MATERIALS AND METHODS

Study Site and Situation

Santiago Island lies on the western tip of the Lingayen Gulf of Luzon, facing the South China Sea. The island supports approximately 1,000 households averaging 6 members each. A large fringing reef provides the principal means of support through fishing and gathering (del Norte et al. 1989; McManus 1989ab; McManus and Mehez 1989; del Norte and Pauly 1990; McManus and Rivera 1990). The reef (Fig. 1) includes a reef flat of 2 approximately 24 km , dominated by seagrass beds intersected by an intricate network of channels and lagoons of up to 12 m depth. At present (1991) more than half of the corals are damaged or dead, with very little resettlement except for a few patches of small, creeping Anacropora

associated with tangled filamentous algal mats.

An irregular intertidal reef crest, consisting of raised limestone pavement, separates the reef slope and reef flat. The slope is a very complex structure extending at least 20 km to the northeast as a subsurface barrier reef. The bottom ranges from smooth and gradual to highly irregular because of ridges, rifts and dense karst depressions. In many areas at 15-20 m, the slope rounds off into a wall extending to 20-30 m, or into a sand and rubble talus slope of 10-20 degrees broken by coraJ mounds. The estimated 1,000- 1,100 species of

-2­ fish on the slope (Jaranilla and McManus, 1991) form indistinct and temporally variable aggregations influenced by depth (possibly including temperature), salinity, and roughness, especially at scales of less than 1 m (Nafiola et al. 1990). The estimated 300-500 species of scleractinian corals are generally found covering 10-20% of the bottom amid diverse benthic plant and animal assemblages, although dense coral patches covering hundreds of km 2 occur sporadically. Visible coral destruction ranges from very little to 50% of

hard corals, often witn evident blast patterns or standing dead coral. Unlike the reef flat, the corals of the reef slope include many resettled colonies of a broad variety of species growing on or amid damaged corals.

Most of the fishermen of the reef flat use bamboo rafts or small (3-15 m) double outrigger canoes (bancas). On calm days, large numbers of bamboo raftsmen fish the upper forereef slope. Usually, however, most of the boats on the forereef slope are moderate-sized (8-12 m) bancas with 15-20 hp engines. Most of the anchors are grappling hooks constructed from iron reinforcing rods, with a span of generally 0.3 - 1 m, designed to catch on corals. There are a wide variety of fishing gear (del Norte et al. 1989), including hand lines, spears, gill nets, drive-in nets, traps, corrals, push-rakes and extremely fine-mesh trawls ('karukod', used in seagrass areas for early juvenile fish). Several hundred species of fish, invertebrates, and seaweeds are caught or gathered for

-3­ subsistence consumption or marketing. The fishermen occasionally farm or acquire alternative employment. However, neither of these is consistently profitable enough to sustain a family. Very few fishermen have savings, and there is much difficulty during times when fishing is poor or hazardous as during stormy periods. The fishing population tends to increase over time because of rapid population growth and a lack of employment elsewhere, and competition for existing resources is increasing. The occasional immigration of new ethnic groups in the past has led to intergroup compecition which has strongly exacerbated the problem and contributed to the demise of traditional fishing right patterns. One result of this pressure is the current teidency to use destructive fishing gear to obtain short-term high returns at the expense of long-term resources.

A variety of explosive devices are used for fishing. Most of the devices described as being in use in soft-bottom fisheries are also used on the study reef (Galvez and Sadorra 1988; Armada 1989; Calud et al. 1989; Galvez 1989; Galvez et al. 1989). An additional local eyplosive material is boat-building foam, finely ground and mixed with gasoline.

Large firecrackers are aiso employed occasionally. The most common devices on the study reef are beer, gin, or soft drink bottles filled with layers of powdered potassium nitrate and pebbles, and carrying a commercial fuse and blasting cap to

-4­ permit subsurface delayed ignition. The potassium nitrate is readily available commercially, and is sold for spraying mango trees to induce flowering. A small amount of gasoline is added immediately prior to use. A single bomb cFn cost 1-2 U.S. dollars (USD) to construct. Some fishermen claim that a good catch can be 10-20 kg, with a market value of 15 - 40 USD. Many fishermen lose limbs or lives to premature explosions, but the return on investment is considered to be high enough to warrant the risk (Galvez et al. 1989).

Use of fish poisons is far more common than is generally assumed. Local fishermen use poisons derived from leaves, roots, and berries of several plant species. Chlorox and insecticides have reportedly been used in tide pools. Sodium cyanide is believed to be the most prevalent poison. When used to collect fish for food, the poison is often premixed with small bits of fish or shrimp, and broadcast by hand or ladle in the area around a boat. During more than 50 hours of observation from an ultralight aircraft, cne of us (JM) has witnessed a procedure three times during which a moderate sized banca in shallow water circled about as a cloud of a white substance was broadcast. Ten to 20 fishermen on individual bamboo rafts were present to retrieve fish. A general lack of medical pe-'sonnel, facilities and knowledge in these areas makes it difficult for fishermen and researchers to know if any ill-effects commonly arise from consumption of fish caught this way.

-5­ Sodium cyanide is the principal means by which fish are captured for the aquarium industry in the study area (in spite of a few ill-fated attempts to train fishermen in the use of net- capture techniques -- e.g. Rubec 1986). The cyanide is obtained as a tablet, and mixed with seawater immediately before use in small squeeze bottles. A skin diver applies the poison by squirting the fluid at the desired fish or its abode among the corals (Galvez et al. 1989). Alternatively, the tablet may be secured whole to a stick and held in the vicinity of the fish. The fish becomes narcotized for easy capture, and often emerges from protective cover as it experiences respiratory stress. These fish experience a high mortality after transit to international locations, and the Philippine aquarium export industry suffers great losses

because of its reputation for use of this technique (Albaladejo and Corpuz 1981; Rubec 1986, 1988). However, the

short term gains of immediate sales outweigh the potential

losses of future markets in the competitive Malthusian fishery situation. A single tablet costs on the order of 25 to 50 costs (US). The cyanide is often sold secretly. Each tablet may suffice for two squeeze bottles, the tablet often being broken in the teeth of the fisherman.

Some fishermen use hookah rigs, and share with many spearfishermen problems with decompression sickness from excessive depths and diving times. A diver's net return is believed to considerably exceed that of the average fisherman

-6­ in the area, roughly one US dollar per fishing day (Ahonuevo 1989).

Field Data

Field observations of the fishery and reef, and interviews with fishermen were conducted over a 12 year period, but principally during the period of monitoring from June 1986 to December, 1990. The three authors have accumulated over 700 hours in underwater observations and 50 hours of aerial observation at the study site.

In July 1986, the blast situation among lagoonal corals was investigated by a single diver (JM) swimming four transects of approximately 1 km each northward from four points along the northern coast of Santiago Island in a single day (Fig.l). Each patch of coral investigated (generally 2-10 m diameter) was assessed as to percent living coral. Notes on regrowth of

corals were made then and frequently over the years 1986-1990.

An ongoing program of fish community monitoring required teams of divers to visually survey 18 transects on the forereef slope on alternate months (Nahola et al. 1990). During the period 11/87 - 9/89, selected divers recorded time in the water and the number of audible blasts during the dive. Listening periods less than 6 minutes were eliminated to

-7­ reduce recording biases, leaving 87 sampling times totalling 30 hours.

A concurrent program of fishery monitoring required that all boats fishing on the forereef slope be mapped at midday on a random day each week. Days were selected using a random number table such as that in Freund (1979), starting from column and row seed numbers called out by disinterested parties, and choosing sequentially (by row) values from 1-7 for days to survey each week. Those engaged in the survey were hired from local villages, and were able to determine which boats were likely to be involved in blast fishing. For the present analysis, total boats and potential blasting boats were tallied for the period 5/23/89 - 12/16/90.

Assumptions-and Calculations

A description of the logic behind inputs and calculations in the balance sheet model is given by table and line number. Table 1. [1] The divers operate only under selected weather conditions. Because of the problem of visibility for targeting and retrieving the fish, blast fishermen tend to be limited by similar weather restrictions. Values are mean and 90% confidence limits for blasts per hour on such "good" days based on 89 periods of underwater blast counting. [2] Good hours per day are estimated from experience with fishermen activity patterns. [4] Typhoons and other periods during which

-8­ the water visibility is poor because of rain, wind, or siltiness after storms are periods wherein blasting is restricted. (7] Our observations corroborate previous reports of a blast damage radius of 0.5 - 2 m (Mathias and Langham 1978; Maclean 1988). There is often a further area of dead coral nearby. Scleractinian corals have a double layer of protoplasm surrounding and penetrating a hard skeleton (Veron 1986). Corals are susceptible to a wide variety of infectious organisms (Antonius 1981a,b; Peters 1984), and exhibit self-lysis and sloughing if disturbed severely (Antonius 1981b). It is likely that shock waves from a blast could initiate infection or sloughing over a wider area than the actual breakage. Input values are estimated. [9] Hard substrate on the forereef slope tends to exhibit 10-30% hard coral cover. However, there is a substantial area of sand cover in pockets and channels at any site. [12] The illegality of blasting makes it difficult to determine the effective listening radius. We have found that blast auditory intensity is sharply reduced as one descends down along a wall away from shallow blasting. Therefore roughness, especially at the scale of 10's of m, will cause variability in effective listening radii. A knowledge of blasting areas, comparative discussions with surface personnel post-dive, and various other intuition building activities lead us to assume a listening radius of 2 km with an error distance of 1 km. [17] Coral radii figures are based on crude estimations only. If the radii included the broadest extent of branching corals,

-9­ the value would be higher. However, for purposes of conceptualizing growth processes, colonies of branching corals are visualized as massive ("head") corals of smaller radii. [19] Linear growth rates of corals vary from 0.5 -18 cm/yr in the Philippines (Gomez et al. 19'5). However, higher growth rates are for branching corals (Yap and Gomez 1981, 1984,

1985a). Massive corals have smaller growth rates, probably partly because of the higher density of aragonite crystals in the skeleton. In keeping with the concept of reducing corals to massive counterparts, smaller growth rates are used. The growth rate of the average coral would be further decreased

when accounting for natural mortality among the measured population, i.e. some corals "stop growing", and this factor is excluded from most growth rate estimations. Growth rates vary with environmental conditions (Shinn 1966; Yap and Gomez 1984, 1985a; Huston 1985), and with effects of fish feeding on them (Neudecker 1977). [27] Alifio et al. (1985) found that combined soft and hard corals on a cleared area of 42 m2 of back reef after one year had reached only 1% of initial cover. Considerable uncertainty about settling rates exist. However, as indicated in line 29, new corals contribute insignificantly to annual regrowth even if abundant. Resettled corals account for significant cover only after a few years of growth, and in this discrete model, any coral over one year old is already part of the preexisting population.

Table 2. [33] Only aquarium fish collectors are included in

-10­ this model, although inclusion of those using sodium cyanide for capturing food fish might substantially increase damage estimates. The number of users was obtained from interviews, and is tenporally variable. [34] Much aquarium fish collection still occurs in the limited corals of the reef lagoon, where a variety of colorful juvenile fishes settle frequently. The extent of fishing may be more restricted than with blasting. [36] Numbers of bottles used were determined from limited interviews. [38] The greatest problem with this assessment is the fact that the mortality of corals exposed to cyanide poisoning is apparently virtually unknown (Rubec 1986). Some figures are applied here merely to demonstrate the possible range of effects and the need for refining the estimates in future studies. [45] The mean number of boats and 90% confidence intervals are as determined from 101 sampling periods. [46] The number of anchor drops is based on interviews and experience with fishing practices. [48] The total area in which fishing occurs is a figure which must be qualified with respect tu how frequently a portion of reef must be fished before it is to be included in the calculation. The given figures are used for comparative evaluation and are crude. [50] The dsual anchor is designed to catch on coral. The average anchor drop probably results in substantial damage to one large coral (1 - 2 m diameter) and several much smaller corals across which it has been dragged before hooking and upon retrieval. This factor greatly increases the assumed damage from anchors to the corals. The damage is greater for

-11­ branching corals (although some may regenerate from fragments -- Highsmith 1982; Sammarco 1982), and this may help to explain the lack of dominance by these faster growing formns in some areas not exposed to violent seasonal wave action.

-12­ RESULTS

Field observations revealed a substantinl amount of dead and fragmented coral in many areas. In lagoonal areas, 62% ± 8% (90%CI, n=58) of all hard coral (excluding rubble) was dead.

Dead coral on the forereef slope was sporadically encountered at levels of up to 50% in some areas, and did not appear to change drastically from year to year. Most areas of damage included signs of exilosions, discernible in the radiating patterns of dead coral (contrary to popular belief, explosives rarely leave craters in the limestone stbstrate -- only among formerly standing corals). The moderate case projection in Table 1 indicates that the blasting rates from 1986-1989 were enough to account for most or all of the potential regrowth of the corals. This would leave the reef extremely susceptible to progressive damage from sporadic natural events such as storm damage, or outbreaks of coral feeding organisms such as Acanthaster planci (Yap and Gomez 1985b) or drupiid snails (Moyer et al. 1982). However, the best and worst case projections indicate considerable uncertainty in these results. At best, the blasting has little or no net effect on the reef. At worst, the reef could be declining at 13% per year in coral cover. The differences in results are due to compounding errors involved whenever two uncertain variables are multiplied to yield a third variable. The field observations tend to support the moderate case projection.

-13­ One interesting conclusion from the analysis is that a reef with small corals will recover fester than a reef of equivalent bottom cover in large corals. This is because with a constant rate of linear growth, a small coral undergoes a greater percentage increase in size each year than a large one. This would indicate that resilience may be greater in a reef sporadically perturbed over many decades than in one in a more protected state which has many large corals covering the same area. The secondary mortality (infection) factor would also favor faster recovery for reefs with smaller corals, because a larger coral has a greater chance of partial damage in many cases.

Anchor damage appears in Table 2 to be nearly as problematic as blasting. The major difficulty is that the anchors are designed specifically to grab, and inadvertently to damage, the corals. The obviousness of the damage on a given reef will depend greatly on the extent to which boats return

constantly to the same spots for fishing activities. Presumably, the fishermen selectively target sites with good coral cover and hence abundant fish. They would tend to return until the coral cover decreases or fish become scarce, and then move to new sites in subsequent months. In this case, more efficient but nondestructive fishing gear would encourage site switching before coral is severely damaged in one spot. However, this may make the damage less readily visible by spreading it over a larger area, but will not

-14­ alleviate tha problem of widespread gradual coral decline if

indeed that is occurring. Helpful measures might include cutting back on the number of fishing boats or changing to sand catching anchors. In tourist diving areas the provision

of permanent moorings would be effective, but on a fished

reef, this inight concentrate destructive or overfishing

effects, or generate conflicts over mooring rights.

Cyanide (NaCN) fishing is the most difficult of the three to evaluate, because of a current dearth of information on the effects of NaCN on corals. The projections indicate that even a small mortality rate in the range of a few percent death in NaCN exposed corals could lead to substantial damage after

repetitive daily fishing in an area by a handful of fishermen.

Figure 2 indicates that blasting tended to taper off sharply at about 1400 hours. Less formal observations indicated that blasting was particularly prevalent from dawn until 1400 hrs

on calm days when water visibility is high. Figure 3 indicates the variability of blast frequencies over several months. Blasting tended to be restricted to coralline areas above 14 - 16 m depth, beyond which targeting and recovery of fish become difficult.

-15­ DISCUSSION

Filling in the Information Gaps

It is very difficult to obtain field mortality rates from blasting and cyanide use because of conflicts with public awareness campaigns and protective legal measures. However, it is clear from these studies that much more information will be necessary before reasonable conclusions can be drawn about resilience of coral reefs to destructive fishing.

Considerable press has been devoted to the problem of cyanide fishing. Most ot this has concerned aquarium collecting, possibly because of its direct impact on a common industry in developed countries. However, the use of cyanide for food fishing may be at least as intensive. Effects of NaCN on corals are not well known. Rubec (1986) cited anecdotal information from personal communications and unpublished reports. The apparently contradictory nature of the results was because none of the information had arisen from formal, controlled field studies. To date, there is apparently no way to estimate the effects of NaCN on coral reefs except in crude terms of the effects on exposed fish and fishermen. It is extremely important that studies be initiated to evaluate coral mortality following exposure to cyanide under field conditions.

-16­ Management Approaches

Figure 4 illustrates the fact that blast fishing declined sharply by mid-1989. This is believed to be the result of a strong crackdown by a renewed local military force. At one point, three boats confiscated from blast fishermen were displayed along a public thoroughfare. Rumors abound of much more severe penalties, which, regardless of veracity, tended to decrease the activity. However, such a legal enforcement campaign cannot continue unabated indefinitely. Divers in December 1990 and January 1991 have noticed occasional blasting activities.

A reasonable conceptual analogue to the blast fishing situation is the problem of enforcing jaywalking in cities. Jaywalking is similarly a very hazardous activity which can have negative effects on the perpetrators, the drivers, and innocent bystanders along the street. It is generally illegal, and should rationally be considered to be truly antisocial behavior. However, with a few exceptions, jaywalking is considered to be a reasonable and socially acceptable activity. The individual generally feels no renirse for what he has done, and often is elated to have made a small gain in time and effort expenditures for the day. Neither jaywalking nor blast fishing will be effectively controlled until ways are found to maL. them socially unacceptable. Merely implementing sporadic training programs

-17­ has not been sufficient, as can be seen in the failure of attempts to train aquarium fishermen to use nets instead of

cyanide in Bolinao. Even in the case of municipal marine

parks, a loss of continuity in conservation promotion can

result in reversion to destructive activities (Maclean 1986;

Alcala 1988; Russ and Alcala 1989; Alcala and Russ 1990).

Because of this, it is unlikely that training activities by temporarily funded organizations are likely to be effective

against blast fishing without the follow-up support of a more permanent organizational structure.

It has previously been suggested that there is a need for well

coordinated national and provincial governmental programs to organize and coordinate village level management schemes. One

such concept is the Coastal Adaptive Management and Resource

Assessment (CAMRA) scheme proposed elsewhere (McManus 1988;

McManus et al. 1988; McManus and Arida (in press). This program would involve a system of environmental community organizers (ECO's) similar to existing health and postal systems. More importantly, efforts must be directed to alleviate the Malthusian nature of the problem. Primarily, this must involve efforts to reduce population growth rates.

Secondarily, efforts should be directed towards creating alternative livelihoods to keep small-scale fishermen numbers down (Smith 1979), and cooperative agreement schemes to protect the resource from overexploitation in the face of industrial level competition as its value increases following

-18­ proper management (Colin 1989). Fortunately, the economic benefits of proper management are well exemplified in success stories such as the growth of tourist investment in certain village-managed reefs in the Philippines.

ACKNOWLEDGMENTS

The authors wish to thank all who have been involved in the monitoring effort, especially Jesse Cabansag, Elmer Dumeran, June Castrense, Wilfredo Campos, Jerome Cabansag, and Joseph Pasamonte. We would like to thank Perry Alifio, Liana McManus, Noli de Perio, Boyet Elefante, George Ragos, Condrado Gonsaga, Cristopher Diolazo and Flor de Guzman for helpful information. This research was jointly sponsored by USAID Grant No. DAN-4024-G-SS-9113-00, "Biodiversity assessment in Philippine coastal marine and coral reef communities with special emphasis on destructive fishing methods", and the Fisheries Stock Assessment Collaborative Research Support Program (FSA-CRSP), USAID Grant No. DAN-4146-G-SS-5071-00. This is contribution no. xxx, Marine Science Institute, University of the Philippines.

-19­ REFERENCES

Albaladejo VD, Corpuz VT, 1981 A market study of the

aquarium fish industry of the Philippines: an assessment of the growth and the mechanics of the trade. Proc 4th Int Coral Reef Symp 1:75- 81. Alcala AC (1988) Effects of marine reserves on coral fish abundances and yields of Philippine coral reefs. Ambio

17(3) :194-199. Alcala AC, Russ GR (1990) . direct test of the effects of protective management on abundance and yield of tropical

marine resources. J Cons int Explor Mer 46:40-47. Alifio PM, Banzon PV, Yap HT, Gomez ED, Morales JT, Bayoneto RP (1985) Recovery and recolonization on a damaged backreef area at Cangaluyan Is. (Northern Philippines). Proc 5th Inter Coral Reef Congress 4:279-284. Afionuevo C (1989) The economics of municipal fisheries: the case of the Lingayen Gulf. In: Silvestre G, Miclat E, Chua TE (eds) Towards sustainable development of the coastal

resources of Lingayen Gulf, Philippines. ICLARM Conference Proceedings 17, Philippine Council for Aquatic and Marine Research and Development, Los Bafios, Laguna, and International Center for Living Aquatic Resources

Management, Manila, Philippines, pp 141-155 Antonius A (1981a) Coral pathology: a review. Proc 4th Inter Coral Reef Symp 2:3-6.

-20­ Antonius A (1981b) The "band" diseases in coral reefs. Proc 4th Inter Coral Reef Symp 2:7-14. Armada NB (1989) Analysis and evaluation of the use of explosives in illegal fishing in Lingayen Gulf,

Philippines. Working Paper, USAID Fish Stock Assessment CRSP. Calud A, Rodriguez G, Aruelo R, Aguilar G, Cinco E, Armada N, Silvestre G (1989) Preliminary results of a study of the municipal fisheries in Lingayen Gulf. In: Silvestre G, Miclat E, Chua TE (eds) Towards sustainable development of the coastal resources of Lingayen Gulf, Philippines. ICLARM Conference Proceedings 17, Philippine Council for Aquatic and Marine Research and Development, Los Bafios,

Laguna, and International Center for Living Aquatic

Resources Management, Manila, Philippines, pp 3-29. Carpenter KE, Alcala AC (1977) Philippine coral reef fisheries

resources. Part II. Muro-ami and kayakas reef fisheries,

benefit or bane? Philipp J Fish 15:217-235. Clark CW (1989) Bioeconomics. In: Roughgarden J, May RM,

Levin, SA (eds) Perspectives in ecological theory.

Princeton University. Press, Princeton, NJ, pp 275-286. del Norte AGC, Nafiola CL, McManus JW, Reyes RB, Campos WL, Cabansag JBP (1989) Overfishing on a Philippine coral reef: a glimpse into the future. Proc 6th Symp on Coastal Management/ASCE, 4:3087-3097.

-21­ del Norte AGC, Pauly D (1990) Virtual population estimates of

monthly recruitment and biomass of rabbitfish, Sicfanus

fuscescens off Bolinao, northern Philippines. In: Hirano

R, Hanyu I (eds) The second Asian fisheries forum. Asian Fisheries Society, Manila, Philippines, pp 851-854. Freund JE (1979) Modern elementary statistics, 5th ed Prentice-Hall International, Inc, London. Galvez RE (1989) Blast fishing and government response in Lingayen Gulf. Proc 6th Symp on Coastal Management/ASCE,

3:2286-2299.

Galvez RE, Hingco TG, Bautista C, Tungpalan MT (1989)

Sociocultural dynamics of blast fishing in two fishing

villages in the Lingayen Gulf area. In: Silvestre G,

Miclat E, Chua TE (eds) Towards sustainable development of the coastal resources of Lingayen Gulf, Philippines.

ICLARM Conference Proceedings 17, Philippine Council for

Aquatic and Marine Research and Development, Los Bahos,

Laguna, and International Center for Living Aquatic

Resources Management, Manila, Philippines, pp 43-62.

Galvez RE, Sadorra MSM (1988) Blast fishing: a Philippine case

study. Tropical Coastal Area Management 3(l):9-10.

Gomez ED, Alcala AC, Yap HT, Alcala LC, Aliho PM (1985) Growth

studies of commercially important scleractinians. Proc 5th Int Coral Reef Congress 6:199-204

Highsmith RC (1982) Reproduction by fragmentation in corals. Mar Ecol Prog Ser 7:207-226.

-22­ Huston M (1985) Variation in coral growth rates with depth at Discovery Bay, Jamaica, 4:19-25.

Jaranilla HS, McManus JW (1991) Applications of jackknife

estimations of species richness and diversity to a coral

reef fish community in Bolinao, Philippines. Working

paper, USAID Fish Stock Assessment CRSP.

Maclean JL (1986) End of a marine reserve: Sumilon revisited.

Naga, the ICLARM Quarterly, 9(l):13.

Maclean JL (1988) Blast fishing and poisoning threaten the

Philippines' last undersea wilderness area. Naga, the ICLARM Quarterly 11(4):14-16.

Mathias JA, Langham NPE (1978) Coral reefs. In: Chua TE,

Mathias JA (eds) Coastal resources of western Sabah. Penerbit Univ Sains Malaysia pp 117-151.

McManus JW (1988) Coral reefs of the ASEAN region: status and management. Ambio, 17(3)189-193.

McManus JW, Arida CC (In Press) Philippine coral reef

management. In: Philippines Recommends for Fisheries.

Philippines Recommends Series. Philippine Council for

Aquatic and Marine Research and Development, Los Bafios, Philippines.

McManus JW, Ferrer EM, Campos WL (1988) A village-level

approach to coastal adaptive management and resource

assessment (CAMRA) . Proc 6th Int Coral Reef Symp 2:381-386.

-23­ McManus LT (1989a) Coralline resources of Lingaven Gulf, Philippines: a proposal for their management. Proc 6th Symp on Coastal and Ocean Management/ASCE, 4:3098-3107. McManus, LT (1989b) The gleaners of northwest Lingayen Gulf,

Philippines. Naga, the ICLARM Quarterly 12(2):13. McManus LT, Mefiez LA (1989) Status of coralline resources in Lingayen Gulf. In: Silvestre G, Miclat E, Chua TE (eds) Towards sustainable development of the coastal resources

of Lingayen Gulf, Philippines. ICLARM Conference Proceedings 17, Philippine Council for Aquatic and Marine Research and Development, Los Bafios, Laguna, and International Center for Living Aquatic Resources

Management, Manila Philippines, pp 63-70.

McManus LT, Rivera RA (1990) Population and socioeconomics.

In: McManus LT, Chua TE (eds) The coastal environmental

profile uf Lingayen Gulf, Philippines. International

Center for Living Aquatic Resources Management, Manila, Philippines pp 38-43. Moyer JT, Emerson WK, Ross M (1982) Massive destruction of scleractinian corals by the muricid gastropod, Drupella in Japan and the Philippines. The Nautilus 96(2):69-82. Nafiola CL, McManus JW, Campos WL, del Norte AGC, Reyes RB, Cabansag JPB, Pasamonte JND (1990) Spatio-temporal variations in community structure in a heavily fished forereef slope in Bolinao, Philippines. In: Hirano R, Hanyu I (eds) The second Asian fisheries forum. Asian Fisheries Society, Manila, Philippines, pp 377-384.

-24­ Neudecker S (1977) Transplant experiments to test the effects of fish grazing on coral distribution. Proc 3rd Int Coral Reef Symp 1:317-323. Pauly D (1988) Some definitions of overfishing relevant to coastal zone management in Southeast Asia. Tropical Coastal Area Management 3(1):14-15.

Peters, EC (1984) A survey of the normal and pathological histology of scleractinian corals wi,.h emphasis on the effects of sedimentation stress. PhD thesis, University of Rhode Island. Rubec PJ (1986) The effects of sodium cyanide on coral reefs and marine fish in the Philippines. In: Maclean JL, Dixon LB, Hosillos LV (eds) The first asian fisheries forum.

Asian Fisheries Society, Manila, Philippines, pp 297-302. Rubec PJ (1988) Cyanide fishing and the international marinelife alliance net-training program. Tropical Coastal Area Management 3(l):11-13. Russ GR, Alcala AC (1989) Effects of intense fishing pressure on an assemblage of coral reef fishes. Mar Ecol Prog Ser 56:13-27. Sammarco PW (1982) Polyp bail-out: an escape response to environmental stress and a new means of reproduction in corals. Mar Ecol Prog Ser 10:57-65. Shinn EA (1966) Coral growth rate, an environmental indicator. J Paleontology 40(2):233-241.

-25­ Smith IR (1979) A research framework for traditional

fisheries. ICLARM studies and reviews no 2. International

Center for Living Aquatic Resources Management, Manila, Philippines.

Veron JEN (1986) Corals of Australia and the Indo-Pacific.

Angus & Robertson Publishers, North Ryde, NSW, Australia. Yap HT, Gomez ED (1981) Growth of Acropora pulchra (Brook) in

Bolinao, Pangasinan, Philippines. Proc 4th Inter Coral Reef Symp 2:207-213. Yap HT, Gomez ED (1984) Growth of Acropora pulchra II.

Responses of natural and transplanted colonies to temperature and day length. Mar Bio 81:209-215. Yap HT, Gomez ED (1985) Growth of Acropora pulchra III. Preliminary observations on the effects of transplantation

and sediment on the growth and survival of transplants. Mar Bio 87:203-209.

Yap HT, Gomez ED (1985) Coral reef degradation and pollution

in the East Asian Seas region. UNEP Regional Seas Reports & Studies No 69, pp 185-207.

26­ Table 1. Balance sheet for coral recovery following blast fishing. The most reasonable estimates indicate that regrowth is barely sufficient to replace blasted coral cover, and would reduce the resilience of the reef to perturbations such as storms or Acanthaster planci activity. However, worst and best case scenarios demonstrate that compounding errors make quantification of effects'very difficult. (* = input variables at precision shown).

Cases: Worst Moderate Best How many blasts? 1 Number of blasts per good hour 12.4 10.1 7.7 2 Number of good hours per day 8 6 4 3 Number of blasts on a good day 99.2 60.6 30.8 4 Percent bad weather days per 10% 20% 30% year 5 Number of good days per year 329 292 256

6 Number of blasts per year 32,587 17,695 7,869 How much damage? 7 Radius of coral kill per 2.0 1.0 0.5 blast (m) 8 Area affected per blast (sq.m) 12.6 3.1 0.8 9 Percent coral cover in that 5% 10% 20% area 10 Coral affected per blast 0.63 0.31 0.16 (sq.m)

11 Coral damage/yr listen, area 0.02 0.006 0.001

(sq.km) 12 Listening radius 1 2 3 13 Listening area (sq.km) 3.1 12.6 28.3

14 Coral loss per sq.km. (sq.km) 0.01 0.0004 0.00004

-27­ Cases: Worst Moderate Best How many blasts?

15 Initial coral/sq.km. (sq.km) 0.05 0.1 0.2 16 Percent of coral lost per 13% 0.44% 0.02% year How much recovery possible? 17 Ave. radius growing coral (m) 0.3 0.2 0.1 18 Starting area/coral (sq.m) 0.28 .0.13 0.03 19 Radial growth/yr (m) 0.005 0.010 0.02 20 Ending area/coral (sq.m) 0.29 0.14 0.05 21 Area gained/coral/yr (sq.m) 0.010 0.013 0.014 22 Coral area/sq.km. (sq.km) 0.05 0.10 0.20 23 Number corals per sq.km 176,839 795,775 6,366,198 24 Number of corals killed/ 23,051 3,520 1,392 sq.km.

25 Remaining corals each year 153,788 792,254 6,364,806 26 Area coral growth/sq.km./yr 0.001 0.010 .0.088 (sq. km)

27 Percent of corals replaced/yr 0.1% 1% 50% 28 Number new corals/yr 23 35 696 29 New coral area after 6 mo 2E-09 1E-08 9E-07 (sq.km)

30 Total coral growth/sq.km. 0.001 0.010 0.088 31 Percent total coral growth 0.1% 1.0% 9% per year 32 Percent net gail of coral/yr -13% 0.6% 9%

-28- Table 2. Coral damage from cyanide and anchor use. Estimated effects of fishing with sodium cyanide on corals range from negligible to extreme. Without further field data on mortality in corals from cyanide, no reasonable assessments of effects are possible. Anchors account may for as much mortality as blasting because they are designed to grab corals. Repetitive use in favored sites leadd to noticeable effects. (Calculations are continued from Table 1. * = additional input variables).

Cases: Worst Moderate Best How important is cyanide? 33 Total number of users 80 40 20 34 Area of use (sq.km) 10 20 30 35 Users/sq.km 8.0 2.0 0.7 36 Bottles/hour good hours 4 2 1 37 Corals affected per bottle 100 50 20 38 Percent of corals that die 20% 5% 1% 39 Corals killed par bottle 20.0 2.5 0.2 40 Corals killed/hr/user good 80.0 5.0 0.2 hours 41 Good hours per day 8 6 4 42 Good days per year 329 292 256 43 Corals killed/yr/sq.km. 1,681,920 17,520 136 44 Percent of corals killed 951% 2% 0.002% 45 Total number of boats/day 25.0 23.0 20.9 46 Number of anchor drops/day/ 4 3 1 boat 47 Number of anchor drops/day 100 69 21 48 Total area of fishing (sq.km) 40 30 20 49 Drops per sq.km./day 3 2 1

-29­ Cases: Worst Moderate Best Now important is anchor damage?

50 Number corals killed per drop 10 5 1 51 Good days per year 329 292 256

52 Corals killed/yr/sq.km. 8,213 3,358 267 53 Percent of corals killed 5% 0.4% 0.004% each year

-30­ Fig. 1. Map of Santiago Island showing 10 visual transect sites on the reef slope (V), and 4 northward swimming

transects on the reef flat (bars). Data on blast frequencies

was gathered during fish surveys on the reef slope, 1987-19S0. The reef flat transects were used to establish that more than half of the lagoonal hard corals (excluding rubble) were dead in 1986.

Fig. 2. Blast frequencies noted by SCUBA divers plotted against time of day. No data is available before 0930 hrs, but blasting is known to begin soon after sunrise. The graph shows the decline in blasting by 1430 hrs. The line is a 5 pt running mean used to indicate the data trend. Vertical bars indicate times for which data were available.

Fig. 3. Blast frequencies plotted by date of sampling, showing variability around the mean of 10.1 blasts/hr at the height of activity. The line connects the means for each survey period.

Fig. 4. Frequencies of boats/day on the reef slope, sampled on a random day each week in late morning. The numbers of boats recognized as potentially engaged in blast fishing are plotted with vertical bars. The graph shows the effectiveness of strict antiblasting enforcement by mid-1989.

-31­