source Ecology of the Coral Reef System Rodolfo B. Reyes, Jr. Kathleen N. Kesner Association of Southeast Asian NationNnited States Coastal Resources Management Project International Center for Living Aquatic Resources Management Fisheries Stock Assessment-CollaborativeResearch Support Program University of Rhode Island University of the Philippines Marine Science Institute Resource Ecology of the Bolinao Coral Reef System JOHN W. Mc~~NUS CLETOL. NA~JOLA,JR. RODOLFOB, REYES, JR. KATHLEENN. KESNER Published by the International Center for Living Aquatic Resources Management on behalf of the Association of Southeast Asian Nationmnited States Coastal Resources Management Project. Printed in Manila, Philippines. McManus, J.W., C.L. Naiiola, Jr., R.B. Reyes, Jr. and K.N. Kesner. 1992. Resource ecology of the Bolinao coral reef system. ICLARM Stud. Rev. 22,117 p. Cover: (Front) Reef flat including Silaki Island. The spottiness results from patches of coral, sand and seagrass of various densities. (Back) A gillnet against the backdrop of a Bolinao sunset. All photos by J.W. McManus. ISSN 0115-4389 ISBN 971-8709-28-2 ICLARM Contribution No. 844 MSI Contribution No. 212 CONTENTS List of Acronyms and Abbreviations List of Tables vii List of Figures Acknowledgments Dedication Foreword xvi Abstract Chapter 1. Introduction Chapter 2. The Harvest of the Reef General Monitoring the fishery Slope fisheries Reef flat fishery Ove~allstudy results Chapter 3. Reef Slope Fish Communities General Monitoring the reef slope Data calculations Fish abundances Species diversity Effects of harvest on fish species diversity Chapter 4. Reef Flat Fish Communities General Monitoring the reef flat Fish abundances Species diversities Chapter 5. Reducing the Rate of Exploitation General Reducing fishing effort Types of overfishing How much harvest effort should there be? Chapter 6. A Proposed Marine ReserveIPark System General The need for a reserve The reservelpark system Implications for fishery patterns Suggested implementation Chapter 7. Recommendations for Management Action Overview Regulating tourism Developing alternative livelihoods Mariculture and agriculture Establishing marine reserves Blast and cyanide fishing Banning compressor diving Improving fish-handling facilities Reducing human population growth rates References Appendices. Fish Species Abundances 1. Combined list of all species sorted alphabetically. 2. Reef slope species by frequency. 3. Reef slope families by frequency. 4. Reef flat species by frequency. 5. Reef flat families by frequency. 6. Reef flat night trawl species by frequency. 7. Reef flat night trawl families by frequency. 8. Reef flat night trawl species by weight. 9. Reef flat night trawl families by weight. LIST OF ACRONYMS AND ABBREVIATIONS Association of Southeast Asian NationdUnited States Coastal Resources Management Project CPUE catch per unit effort DA Department of Agriculture DAP Development Academy of the Philippines DAR Department of Agrarian Reform DENR Department of Environment and Natural Resources EIA environmental impact assessment FSA-CRSP Fisheries Stock Assessment-Collaborative Research Support Program GPS global positioning system hp horsepower MEY maximum economic yield MSY maximum sustainable yield NGO nongovernmental organization SEC Securities and Exchange Commission TURF territorial use rights in fisheries USAID United States Agency for International Development LIST OF TABLES 1.1 Seasonality of selected reef resources. Dates are approximate. Harvestore must often shift between target resources seasonally. 1.2 Prices of major marine and freshwater commodities set for the Bolinao fish market by the municipal government. Actual prices vary with avaiIability. 2.1 Differential catches of major reef flat gear. Numbers represent the percentage of the 1989-1990 catch that each taxon contributed to each gear (+ is 4%).Species shown are those which ranked in the top five for one or more gear. The table has been extracted from one sorted by reciprocal averaging, so that the species are grouped by similar gear affinities and the gear, by similar catches. 7.1 Potential products from mangrove forests (Saenger et al. 1983; Salm and Clark 1984). 7.2 Skilled labor available in the Bolinao municipality. A variety of human resources could be tapped for small-scale industry. Data are from a survey by DAR in 1991. LIST OF FIGURES Map showing the extent of the Bolinao municipality and reef system. Map of reef areas and adjacent landmarks in Bolinao. Chart of the subsea topography around Santiago Island. Some fields of study which have direct relevance to CRM. Others which could have been added include public health, nutrition and food science. Education and occupation factors affecting development in Bolinao. Data from surveys by DA in 1990 and DAR in 1991. Human population growth in Bolinao. Based on a log-linear regression of historical levels. Data are from the National Census and Statistics Ofice. Mrljor full- and part-time occupations in Bolinao. Fishing is the least profit- able full-time activity, but shellcraft is the most profitable part-time job. Data are from a survey by DA in 1990. Cumulative percentage of boats found at each distance from the reef crest. Monthly boat distances from the reef crest. Relationship between the distance from the reef crest and the area of the reef slope. The nearly straight relationship is a result of the trapezoid-like shape of the reef slope. Price of regular gasoline, based on purchases at a local filling station. The sharp rise in price in December 1990 occurred because of government pricing at the time of the Gulf War. Harvest and fishing effort for the Santiago Island reef flat and lagoon. Effort figures exclude traps and corrals. Catch rates (CPUE)of major gear. The most seasonal catch rates are those from spearfishing on the reef slope. The corral graph omits large catches obtained twice each year during the spawning migrations of Siganus fuscescens (rabbitfish, barangen). Distribution of fish lengths caught by handliners on the reef slope, indica- ting a decline in the numbers of fish longer than 30 cm. Harvest data on sea cucumbers and shells from Lucero on Santiago Island. The alternation of seasons leads to shifting occupations among some hawestors. Data are from a survey by de Guzman 1990. Primary gear use areas on the Santiago Island reef. A large area of the reef flat is rented to Ash corral owners by the municipality. During the spawn- ing migrations of Siganus fuscescens (barangen), other harvest activi- vii ties in this area are prevented by the corral owners. Fishing gear use on the reef dope is more uniform than on the reef flat, but varies in intensity with distance from the reef crest. Comparison of seasonality in gillnet harvests in a nonreef soft-bottom area and on the eastern reef flat. Top species by weight in the shore landings of Bolinao. The irregular pat- terns are the result of the interplay of factors affecting the fish populations and hawest activities. Fish drawings are by Magnus Olsson-Ringby. Harvests from a nonreef longline fishery adjacent to Santiago Island. Profile of the Santiago Island reef, showing the flat and slope separated by a wave-breaking intertidal crest. The profile is based on a transect running northwards to the west of Silaki Island (3x vertical exaggeration). Seasonality in bottom salinity and temperature in 18 reef slope sites. Ver- tical bars are 95% confidence limits. Sampling sites around Santiago Island, Bolinao. S, F = slope and flat visual transect sites, T = trawl sites, L = fish landing sites. Permanent markings on the reef slope transect sites. Abundance and diversity by transect on the reef slope. Vertical bars are 95% confidence limits (left: all life stages; right: by life stage where black = recruits, dashed = subadults and dotted = adults). Nundances of fish recruits (top) and adult fish (bottom) on the reef slope. The decline of adults was interrupted only by a temporary pulse in May 1991 which quickly disappeared. Abundance and diversity of adult fish on the reef slope. Abundances of the most common species in the reef slope visual censusing (grey = combined sizes, black = recruits, dotted = adults). Fish drawings are by Magnus Olsson-Ringby. Diversity in combined transects on the reef slope. Vertical bars represent 95% confidence limits determined from variances obtained by jackknifing among sites (left: all life stages; right: by life stage where black = recruits, dashed = subadults and dotted = adults). Illustration of predator-mediated coexistence. The predator favors the more abundant species, preventing it from excluding the weaker compe- titor. Some possible effects of fishing on a community. Species are represented * by bars arranged initially in rank order by abundance. People can act as predators andlor as removers of predators to cause a variety of possible changes. Species abundance profiles of adult reef slope fish from year-end months. Many species appear to have "fallen off' as overall abundances declined. Bottom salinity and temperature measurements from six reef flat sites. Vertical bars are 95% confidence intervals. Abundances of selected commercially important invertebrates in 50 quad- rats on the reef flat near Lucero. Vertical bars are 95% confidence limits. The graphs are based on unpublished data of A de Guzman 1990. Seasonal variation in seagrass cover on the reef flat. The greatest effect is seen as an annual loss of dense areas, indicating that thinning rather than contraction