Angel C. Alcala

Marine reserve benefits local fisheries.

The utility of no-take marine reserves as fisheries-management tools is controversial. It is hypothesized that marine reserves will help to sustain fisheries external to them by becoming net exporters of adults (the “spillover effect”) and net exporters of propagules (the “recruitment effect”). Local fishery benefits from spillover will likely generate support from fishing communities for marine reserves. We used underwater visual census to show that biomass of Acanthuridae (surgeonfish) and Carangidae (jacks), two families of reef fish that account for 40–75% of the fishery yield from Apo Island, Philippines, tripled in a well-protected no-take reserve over 18 years (1983–2001). Biomass of these families did not change significantly over the same period at a site open to fishing. The reserve protected 10% of the total reef fishing area at the island. Outside the reserve, biomass of these families increased significantly closer to (200–250 m) than farther away from (250–500 m) the reserve boundary over time. We used published estimates of fishery catch and effort, and fisher interviews (creel surveys) to show that the total catch of Carangidae and Acanthuridae combined at Apo Island was significantly higher after (1985–2001) than before (1981) reserve establishment. Hook-and-line catch per unit effort (CPUE) at the island was 50% higher during 1998–2001 (reserve protected 16–19 years) than during 1981–1986 (pre-reserve and early phases of reserve protection). Total hook-and-line effort declined by 46% between 1986 and 1998–2001. Hook-and-line CPUE of Acanthuridae was significantly higher close to (within 200 m) than far from the reserve. CPUE of Carangidae was significantly higher away from the reserve, possibly reflecting a local oceanographic effect. The benefits of the reserve to local fisheries at the island were higher catch, increased catch rate, and a reduction in fishing effort. The fishery and tourism benefits generated by the reserve have enhanced the living standard of the fishing community.

Marine reserves: long-term protection is required for full recovery of predatory fish populations

No-take marine reserves are advocated widely as a potential solution to the loss of marine biodiversity and ecosystem structure, and to over-fishing. We assess the duration of protection required for unfished populations of large predatory reef fish to attain natural states. We have monitored two marine reserves at Sumilon and Apo Islands, Philippines, regularly for 17 years (1983–2000). The biomass of large predatory fish was still increasing exponentially after 9 and 18 years of protection at Sumilon and Apo reserves, respectively. There was little evidence that the rate of accumulation of biomass inside the reserves was slowing down even after so many years of protection. This suggests that the length of time to full recovery will be considerable. We made two assumptions in order to estimate this period. Firstly, that biomass growth will follow the logistic model. Secondly, the conservative assumption that biomass had already attained 90% of the local carrying capacity of the environments in the reserves. We conclude that the time required for full recovery will be 15 and 40 years at Sumilon and Apo reserves, respectively. Such durations of recovery appear consistent with known life history characteristics of these fish, and with empirical data on recovery rates of heavily exploited fish stocks. By the time the full fisheries or ecosystem benefits from such reserves are apparent, human populations and impacts will have doubled in much of the developing world. Thus, networks of such reserves need to be implemented immediately. Furthermore, the management mechanisms for the reserves need to be successful over timescales of human generations.

No-take marine reserves and reef fisheries management in the Philippines: a new people power revolution.

Abstract The marine-conservation and reef fisheries–management program that exists today in the Philippines had humble beginnings in the 1970s at Sumilon and Apo islands. These islands have produced some of the best evidence available that no-take reserves, protected and managed by local communities, can play a key role in biodiversity conservation and fisheries management. Perhaps more importantly, they served as models for an extraordinary expansion of no-take reserves nationally in the Philippines in the past 2 decades. This expansion contributed substantially to a major shift in national policy of management of marine resources. This policy shift partially devolved responsibility from a centralized government bureaucracy to local governments and local communities. Local governments now comanage, along with the national government, marine resources out to 15 km from the coast. Giving some responsibility for management of marine resources to coastal people dependent upon those resources represents, in a very real sense, another “people power revolution” in the Philippines.

Human fatality due to ingestion of the crab Demania reynaudii that contained a palytoxin-like toxin

Clinical accounts of a human fatality resulting from ingestion of the crab Demania reynaudii are documented. The causative toxin was suggested to be palytoxin on the basis of dose-death time relationships and chromatographic properties.

Marine reserves: rates and patterns of recovery and decline of predatory fish, 1983-2000

The application of no-take marine-reserve status to an area is expected to increase spawning-stock biomass of species targeted by fisheries, and to help sustain fisheries external to the reserve. However, empirical evidence on rates and patterns of increase of density and biomass of target species following closures to fishing, and of decrease when reserve status is removed, remains rare. We have monitored density and biomass of large predatory coral-reef fish (Serranidae [Epinephelinae], Lutjanidae, Lethrinidae, and Carangidae, as a group) visually in two small no-take marine reserves and at two control (open to fishing) sites in the Philippines from 1983 to 2000. At Sumilon reserve a complex history of management allowed 13 measurements of density and biomass at durations of reserve protection of −3 yr (i.e., fished for 3 years after reserve status removed) to 9 yr. At Apo reserve 13 measurements were taken at durations of protection of 1–18 yr. We recorded 11 significant (P < 0.05) changes in density at the four sites over the 17 years, three declines and eight increases. All three significant declines occurred when reserve protection was removed. Four of the eight significant increases occurred when reserve status was applied. This represents some of the best evidence currently available that application of marine-reserve status causes increases in abundance of target species. Three of the four significant increases in density required 4–6 yr of protection. Significant positive linear correlations of mean density of large predators against years of reserve protection were observed at both reserves. The pattern of increase of mean biomass against years of reserve protection was exponential, with biomass initially increasing more slowly than density. Density and biomass increased by factors of 12.2 and 17.3, respectively, during 18 yr of continuous protection in Apo reserve. At Sumilon Island three bouts of unregulated fishing of 1.5–3 yr duration eliminated density and biomass gains accumulated over 5–9 yr of marine reserve protection.

Effectiveness of Marine Protected Areas in the Philippines for Biodiversity Conservation

Quantifying the extent to which existing reserves meet conservation objectives and identifying gaps in coverage are vital to developing systematic protected-area networks. Despite widespread recognition of the Philippines as a global priority for marine conservation, limited work has been undertaken to evaluate the conservation effectiveness of existing marine protected areas (MPAs). Targets for MPA coverage in the Philippines have been specified in the 1998 Fisheries Code legislation, which calls for 15% of coastal municipal waters (within 15 km of the coastline) to be protected within no-take MPAs, and the Philippine Marine Sanctuary Strategy (2004), which aims to protect 10% of coral reef area in no-take MPAs by 2020. We used a newly compiled database of nearly 1000 MPAs to measure progress toward these targets. We evaluated conservation effectiveness of MPAs in two ways. First, we determined the degree to which marine bioregions and conservation priority areas are represented within existing MPAs. Second, we assessed the size and spacing patterns of reserves in terms of best-practice recommendations. We found that the current extent and distribution of MPAs does not adequately represent biodiversity. At present just 0.5% of municipal waters and 2.7-3.4% of coral reef area in the Philippines are protected in no-take MPAs. Moreover, 85% of no-take area is in just two sites; 90% of MPAs are <1 km(2). Nevertheless, distances between existing MPAs should ensure larval connectivity between them, providing opportunities to develop regional-scale MPA networks. Despite the considerable success of community-based approaches to MPA implementation in the Philippines, this strategy will not be sufficient to meet conservation targets, even under a best-case scenario for future MPA establishment. We recommend that implementation of community-based MPAs be supplemented by designation of additional large no-take areas specifically located to address conservation targets.

Thinking and managing outside the box: coalescing connectivity networks to build region-wide resilience in coral reef ecosystems

As the science of connectivity evolves, so too must the management of coral reefs. It is now clear that the spatial scale of disturbances to coral reef ecosystems is larger and the scale of larval connectivity is smaller than previously thought. This poses a challenge to the current focus of coral reef management, which often centers on the establishment of no-take reserves (NTRs) that in practice are often too small, scattered, or have low stakeholder compliance. Fished species are generally larger and more abundant in protected reserves, where their reproductive potential is often greater, yet documented demographic benefits of these reproductive gains outside reserves are modest at best. Small reproductive populations and limited dispersal of larvae play a role, as does the diminished receptivity to settling larvae of degraded habitats that can limit recruitment by more than 50%. For “demographic connectivity” to contribute to the resilience of coral reefs, it must function beyond the box of no-take reserves. Specifically, it must improve nursery habitats on or near reefs and enhance the reproductive output of ecologically important species throughout coral reef ecosystems. Special protection of ecologically important species (e.g., some herbivores in the Caribbean) and size-regulated fisheries that capitalize on the benefits of NTRs and maintain critical ecological functions are examples of measures that coalesce marine reserve effects and improve the resilience of coral reef ecosystems. Important too is the necessity of local involvement in the management process so that social costs and benefits are properly assessed, compliance increased and success stories accrued.

Enhanced biodiversity beyond marine reserve boundaries: The cup spillith over

Overfishing can have detrimental effects on marine biodiversity and the structure of marine ecosystems. No-take marine reserves (NTMRs) are much advocated as a means of protecting biodiversity and ecosystem structure from overharvest. In contrast to terrestrial protected areas, NTMRs are not only expected to conserve or recover biodiversity and ecosystems within their boundaries, but also to enhance biodiversity beyond their boundaries by exporting species richness and more complex biological communities. Here we show that species richness of large predatory reef fish increased fourfold and 11-fold inside two Philippine no-take marine reserves over 14 and 25 years, respectively. Outside one reserve (Apo) the species richness also increased. This increase beyond the Apo reserve boundary was 78% higher closer to the boundary (200-250 m) than farther from it (250-500 m). The increase in richness beyond the boundary could not be explained by improvements over time in habitat or prey availability. Furthermore, community composition of predatory fish outside but close to (200-250 m) the Apo reserve became very similar to that inside the reserve over time, almost converging with it in multivariate space after 26 years of reserve protection. This is consistent with the suggestion that, as community composition inside Apo reserve increased in complexity, this complexity spilled over the boundary into nearby fished areas. Clearly, the spillover of species richness and community complexity is a direct consequence of the spillover of abundance of multiple species. However, this spillover of species richness and community complexity demonstrates an important benefit of biodiversity and ecosystem export from reserves, and it provides hope that reserves can help to reverse the decline of marine ecosystems and biodiversity.

Long-term trends in yield and catch rates of the coral reef fishery at Apo Island, central Philippines

Fish yields and catch rates recorded in the 1980s were compared with daily roving creel surveys carried out in 1997/98, 2000 and 2001 at Apo Island. Total annual fish yields were measured six times over the period 1980–2001. Total fish yield was 19–25 t km–2 year–1, with reef and reef-associated fish accounting for 15–20 t km–2 year–1, for five measurements. A sixth measurement, made in 1986, estimated 36.7 t km–2 year–1. Annual yield remained stable over the study period. Carangidae and Acanthuridae accounted for 26–47% and 16–27% of the catch, respectively. Non-reef catches declined over time, from 6.21 t year–1 in 1980/81 to 1–2 t year–1 in 2000 and 2001. Estimates of annual hook and line catch per unit effort (CPUE) increased from 0.13–0.17 kg man–1 h–1 in 1980/81, to 1–2 kg man–1 h–1 in 1997–2001. For target families, hook and line CPUE was consistently higher in 1997–2001 than in 1980–86. However, hook and line CPUE for Carangidae and Acanthuridae declined significantly between 1997 and 2001. Possible reasons for the long-term patterns of fish yields and catch rates are discussed. Differences in methods used in estimates, and changes in gears and fishing effort over the years, make comparisons difficult.

The effect of a minimum length specification on visual estimates of density and biomass of coral reef fishes

The effects of fish length on visual estimates of fish abundance and biomass are assessed based on analyses of size frequency distributions. A 2 cm change in the specified minimum size of fish surveyed produced a calculated change of 14.5 to 126% in numerical estimates. A change of 28.4 to 411% was calculated for a 4 cm change. The extent of the change in the numerical estimate varies with the family considered but, in all cases, was most marked if the specified minimum size was decreased. The effects upon biomass estimates are less marked. In the Scaridae, for example, there is a calculated change of 4.1 to 7.4% for a 2 cm change in the minimum specified size. The changes in the estimates are discussed in relation to the use of visual survey techniques for assessing reef fish standing stocks.