Across the Indo-Pacific marine resources are often managed by common property arrangements that limit access through closures of fishing grounds and gear restrictions (Thornburn, Reference Thornburn2001; Harkes & Novaczek, Reference Harkes and Novaczek2002; Cinner & Aswani, Reference Cinner and Aswani2007). Benefits of these customary practices include increases in fisheries yields (McClanahan et al., Reference McClanahan, Glaesel, Rubens and Kiambo1997), biomass of target species (Cinner et al., Reference Cinner, Marnane and McClanahan2005a,Reference Cinner, Marnane, McClanahan and Almanyb) and abundance (Aswani & Sabetian, Reference Aswani and Sabetian2010). Important ecosystem processes, such as herbivory (Aswani et al., Reference Aswani, Albert, Sabetian and Furusawa2007), and metrics of ecosystem health, such as coral cover, are often higher in areas under customary management (Baird et al., Reference Baird, Campbell, Anggorro, Ardiwijaya, Fadli and Herdiana2005). Integrating these customary systems with contemporary management practices (e.g. spatially defined marine protected areas) is an area of active research (Johannes, Reference Johannes2002; Aswani et al., Reference Aswani, Albert, Sabetian and Furusawa2007), with these alternate forms of marine resource management increasingly being advocated (Graham et al., Reference Graham, McClanahan, MacNeil, Wilson, Polunin and Jennings2008).
Customary management systems are frequently motivated by utilitarian social and economic goals rather than any conservation ethic (Polunin, Reference Polunin1984; Pannell, Reference Pannell1996; Cinner & Aswani, Reference Cinner and Aswani2007). The ability of customary systems to meet community needs such as providing fish for harvest, reducing conflict among resource users and improving yields can lead to higher levels of compliance, and ultimately better ecological outcomes. than externally imposed biodiversity conservation (McClanahan et al., Reference McClanahan, Marnane, Cinner and Kiene2006a; Cinner & Aswani, Reference Cinner and Aswani2007). One of the critical challenges for marine conservation in developing countries, where food security often takes priority over conservation goals, is how to make conservation more compatible with community needs (Drew, Reference Drew2005; Cinner et al., Reference Cinner, Sutton and Bond2007). Governance systems that respect customary knowledge, rules and decision-making processes are more likely to be supported by local communities (Aswani, Reference Aswani2005; Hoffman, Reference Hoffman2006; Tiraa, Reference Tiraa2006) and are common in many Pacific societies (Cinner & McClanahan, Reference Cinner and McClanahan2006; Aswani et al., Reference Aswani, Albert, Sabetian and Furusawa2007; Cinner & Aswani, Reference Cinner and Aswani2007).
Compared with marine customary management in central and eastern Pacific societies there are relatively few examples of community involvement with marine resource management or marine customary law in Indonesia (Cinner & Aswani, Reference Cinner and Aswani2007; Cinner et al., Reference Cinner, Basurto, Fidelman, Kuange, Lahari and Mukminin2012). Community governance structures in Indonesia have often been modified, eroded or overruled by provincial or national legal institutions (Novaczek et al., Reference Novaczek, Sopacua and Harkes2001; Patlis, Reference Patlis2003) or restricted or prejudiced by centralized conservation policies and laws with respect to marine resource access (Thornburn, Reference Thornburn2000; Lowe, Reference Lowe2003), incentives for destructive fishing practices (Thornburn, Reference Thornburn2001; Varkey et al., Reference Varkey, Ainsworth, Pitcher, Goram and Sumaila2010) or disincentives for community participation in management (Novascek et al., Reference Novaczek, Sopacua and Harkes2001; Lowe, Reference Lowe2003). However, as part of the decentralization of governance in many countries, including Indonesia (Thornburn, Reference Thornburn2001; Patlis, Reference Patlis2003), customary practices are becoming enshrined in the legislation of district and local authorities (Janssen, Reference Janssen2005; Gelcich et al., Reference Gelcich, Godoy, Prado and Castilla2008).
Documenting the successes or failures of customary practices improves understanding of the governance frameworks within which marine environments and their resources are most effectively managed (McCleod et al., Reference McCleod, Szuster and Salm2009). Here, we present a case study from Aceh, Indonesia, which examines the socio-economic and ecological conditions of six coastal communities in which a customary management system operates. Our objectives were to examine if aspects of coral reef condition, specifically hard-coral cover, fish biomass and fish assemblage structure, differed between reefs that were influenced by varying management practice, in particular the types of fishing gears restricted. To support our analysis we also investigated whether ecological variation was related to socio-economic variables, including village population size, the number of fishing households, the mean number of occupations, distance to markets, distance to villages and the number of fishing gear types prohibited.
Study area and the Panglima Laot system of customary management
This study was conducted on Pulau Weh, a high continental island located c. 20 km off the northern tip of Sumatra (Fig. 1). Pulau Weh has diverse coral communities that grow primarily on bedrock and in unconsolidated sediments. The coastline is divided into several lhoks (a harbour, and the unit of management in the marine realm). Within six of these lhoks we examined 1–4 sites (15 sites in total; Fig. 1), each with its own set of restrictions on fishing gears (Table 1). One of the lhoks, Iboih, was divided into two separate areas for analysis because some sites within this lhok are managed as a special tourist reserve, Kawasan Wisata, whereas the others are managed by a Panglima Laot. Sites with both high (6–9) and low (2–5) numbers of restrictions on types of fishing gear were located in lhoks on the north, east and west coasts of Pulau Weh.
In Aceh fishing communities employ a customary management system known locally as Panglima Laot. The system was first introduced in the 17th century by Sultan Iskandar Muda (Nurdin et al., Reference Nurdin, Muazzin and Din2004). Fishers in each lhok elect an individual, usually an elder fisherman, the Panglima Laot (literally Commander of the Sea) who meets with fishers every Friday to adjudicate disputes. The Panglima Laot has the authority to adjudicate provincial laws concerning fishing rights except in cases where provincial or national criminal law is violated. The Panglima Laot decides who is entitled to the catch at sea and which fishing gears can be used. He enforces prohibitions on fishing on religious days, initiates searches for lost fishers, decides compensation in the event of boat collisions and arbitrates general disputes over access to the fisheries (Janssen, Reference Janssen2005). The Panglima Laot can also enforce measures to protect the marine environment from land-based threats such as poorly placed development and agriculture. Should a fisher violate the code of conduct for a given lhok, the Panglima Laot has the authority to ground a boat for 1 week at a time, and if the fisher continues to disobey the rules the Panglima Laot can banish boats from the lhok. Other sanctions include monetary fines, and preventing fishers from attending community events. Sanctions or punishments are administered through community meetings and ceremonies to reach consensus among parties (Nurdin et al., Reference Nurdin, Muazzin and Din2004). Fishers must pay a fee to enter the Panglima Laot system, which is used to cover the cost of rescues (C. Wilson, pers. comm., 2009). Importantly, the role of the Panglima Laot is not to manage fishery resources per se but rather to promote social harmony by minimizing conflict among fishers (Nurdin et al., Reference Nurdin, Muazzin and Din2004). This lack of a conservation ethic is summed up by an Acehnese proverb mentioned by Nurdin et al. (Reference Nurdin, Muazzin and Din2004) to describe the philosophy behind Panglima Laot ‘Uleu bak matee, ranteng bek patah’. This saying is translated by Collier et al. (Reference Collier, Horner, Machdi, Wieringa, Graf, Schroter and Wieranga2010) as ‘killing a snake without breaking tree branches’ or, in other words, to solve one problem without creating a new one. The role of the Panglima Laot system in marine resource management has most recently been recognized in 2008, in Provincial Laws No. 9 and 10, which give the Panglima Laot authority to arbitrate customary laws in relation to the sea.
Coral cover and fish biomass
In March 2006 coral cover and fish biomass were estimated along two replicate 50 m transects at two depths (3–4 and 6–8 m) at each of the 15 sites (Fig. 1). Coral cover was recorded at 100 points along each transect, spaced at 0.5 m intervals. Any hard coral (i.e. scleractinian or hydrozoan coral) underlying each survey point was recorded to genus.
The fish assemblages were surveyed along the same 50 m transects used for estimating hard-coral cover. One diver recorded all visually apparent reef fish (i.e., excluding cryptobenthic families Blenniidae, Gobiidae and Tripterygiidae) > 10 cm total length in a 5 m wide belt, and a second diver recorded all fish < 10 cm total length in a 2-m wide belt that extended from the reef substratum to the surface of the water. Individual fishes were identified to species and placed into one of nine size classes (0–5, 5–10, 10–15, 15–20, 20–25, 25–30, 30–35, 35–40 and > 40 cm). Density estimates were converted to biomass using known length–weight relationships; W = aLb , where W is weight (kg), L is total length (cm) and a, b are the indices for a given species (Froese & Pauly, Reference Froese and Pauly2008). To examine variation in fish assemblage structure, individual species were allocated to six trophic groups (corallivores, herbivores, invertivores, omnivores, piscivores and planktivores) following Froese & Pauly (Reference Froese and Pauly2008).
Fishing gears of Pulau Weh
Eight main fishing gears are used on Pulau Weh: reef nets, gill nets, mosquito nets, muroami, hookah, spearguns, handlines and trolling. Reef nets are modified seine nets, not more than 60 m in length, with a height of 8–10 m and a mesh size of 6 cm. They are deployed after dusk from two canoes in calm waters. Gill nets target reef fish, including trigger (family Balistidae), snapper (family Lutjanidae) and emperor fish (family Lethrinidae), and consist of single nylon nets that are either small (length 300–400 m; height 2–5 m) or large (length 800–1,000 m; height up to 15 m). Mesh sizes are 4–11 cm and nets are set passively at the surface or at mid water. Mosquito nets are monofilament nets of 200–300 m length, with a mesh size of < 3 mm, which mostly target anchovies and other small pelagic fishes. Muroami is a technique that primarily targets fusiliers (family Caesionidae) but is non-selective and can catch many reef fish species. The technique involves the use of divers and surface-supplied air (hookah) to chase fish along the reef into a large drive net or purse net (mesh size 2–5 cm) set on reef slopes at depths of 7–30 m. The crew of a muroami operation on Pulau Weh usually consists of 8–10 people. Reef nets and muroami are relatively non-selective, catching fish from many different families. Hookah gear consists of an air compressor with several air hoses of 50–100 m length. Hooker divers use their hands to collect sea cucumber, lobster and troches, and occasionally spears to target grouper Cephalopholis, Epinephelis and Variola spp. (family Serranidae) and gill nets to target aquarium fishes. Spearguns are made from wood, with spears 1.2–2.0 m in length, and are used by fishers on snorkel to target a wide variety of reef fish species, including snapper and grouper. Hook and line fishing is employed from many boat types including canoes and motorized boats, and trolling consists of a single fisher with a hook and line deployed from the rear of a motorized boat.
In December 2006 143 household surveys were conducted by AM and YH in the six lhoks. All respondents were asked to list and rank the occupations of members of the household, from which the mean number of occupations per lhok was calculated. Concurrent with these surveys demographic data were sourced from the Panglima Laot and government records. Data available for each lhok included the population size, number of households, number of households involved in fishing, and mean number of occupations per household (Table 1). At the site level data were available on the distance (m) from survey site to the nearest village (a proxy variable for the likelihood of restrictions being enforced), the distance to the nearest fish market and the number and types of fishing gears prohibited (Table 2).
Variation in hard-coral cover and total fish biomass among lhoks and sites were tested with two nested ANOVAs. Assumptions of the ANOVA were examined using residual analysis. Subsequently total fish biomass was log10(x+1) transformed to improve normality and homoscedasticity; Fisher's LSD tests were used to identify which means contributed to any significant differences among sites or lhoks.
Variation in the functional composition of the fish assemblages among lhoks was analysed using a one-factor multivariate analysis of variance (MANOVA). The analysis was based on the biomass of each of the six functional groups, and was log10(x+1) transformed to improve multivariate normality. A canonical discriminant analysis was then used to examine how the lhoks differed in fish assemblage composition. Ninety-five percent confidence ellipses were plotted around the group centroids (Seber, Reference Seber1984).
The relationships among the socio-economic variables and hard-coral cover and total fish biomass were examined using bivariate correlations and stepwise multiple regressions. The correlations provided an indication of the relationships between hard-coral cover and total fish biomass and each of the socio-economic variables independently, and the multiple regressions examined the combined effects of all socio-economic variables and determined the relative importance of each variable in determining coral cover and total fish biomass. All analyses were performed using STATISTICA v. 7.0 (Statsoft Inc, Tulsa, USA).
The cover of hard corals varied significantly among lhoks (F 6,8 = 4.22, P = 0.033) and sites within lhoks (F 8,42=2.53, P=0.02), ranging from a mean of 10.8 ± SE 4.2% at Paya to 59.6 ± SE 5.2% at Ie Meulee (Fig. 2a). Overall, coral cover was highest at Ie Meulee and Anoi Itam (54.5–59.6%), intermediate at Iboih–Kawasan Wisata (41.9%) and lowest at Iboih–Panglima Laot, Keunekai and Paya (10.8–30.8%; Fig. 2a).
Total biomass of reef fish varied significantly among lhoks (F 6,8 = 3.67, P = 0.047) but displayed no significant variation among sites (F 8,45 = 1.56, P = 0.165). Reef fish biomass was significantly greater at Ie Meulee and Anoi Itam (1,090.4–1,729.4 kg ha−1) than at Kota, Iboih–Panglima Laot, Keunekai and Paya (241.5–444.6 kg ha−1; Fig. 2b). The composition of the reef fish assemblages also varied significantly among lhoks on Pulau Weh (MANOVA, F 5,85 = 2.45, P < 0.001). The canonical discriminant analysis revealed two distinct groups of lhoks along the first canonical variate, which explained 47.4% of the total variation (Fig. 3). Anoi Itam, Ie Meulee and Iboih–Kawasan Wisata were characterized by a greater biomass of corallivores, omnivores, herbivores, and to a lesser extent piscivores and planktivores, than Iboih–Panglima Laot, Keunekai, Kota and Paya (Fig. 3).
The cover of live hard corals was positively related to the number of fishing gears prohibited and lhok population size, and negatively related to distance to village and distance to market (Table 3). The multiple regression analysis suggested that the number of fishing gear types prohibited, population size and the mean number of occupations were the best combination of predictors of hard-coral cover, with the overall model explaining 53% of the variation in coral cover among sites (Table 3). Similarly, total reef fish biomass was positively related to coral cover, the number of gear types prohibited, and negatively related to distance to nearest village and market (Table 4). The multiple regression indicated that coral cover and the number of fishing gears prohibited were the best combination of predictors of reef fish biomass, explaining 32.9 and 6.2% of the variation in fish biomass among sites, respectively (Table 4).
Customary marine resource management practices in the Indo-Pacific are often focused on social goals such as minimizing conflict among coastal communities, rather than western ideals of conservation or fisheries management (Polunin, Reference Polunin1984; Pannell, Reference Pannell1996; Aswani et al., Reference Aswani, Albert, Sabetian and Furusawa2007). Although the primary aim of the Panglima Laot is to minimize conflict among fishers our findings indicate that controls on fishing gears indirectly yield conservation benefits, including healthier coral reefs that support a greater biomass of reef fish and important trophic groups such as herbivores that are essential for promoting reef resilience.
The correlation of coral cover with the number of gears prohibited is most likely a result of the banning of fishing gears, in particular the various types of nets that cause direct mechanical damage to corals and indirect damage by trampling from high numbers of fishers in the water to set the nets and/or scare fish into the nets. The reasons for the gear restrictions are not, however, because of potential damage to the reef but rather because some fishing gears are more likely to create conflict among fishers. Reef nets and muroami, in particular, compete with handlines and spears for many species (e.g. surgeonfish Acanthurus and Naso spp., grouper, parrotfish: Chlorurus and Scarus spp., trevally Caranx and Elagatis spp., and pelagic species such as Caesio and Scomberomorus spp.) and return relatively high rates of catch. The perception among most fishers is that nets deplete local fish stocks, with the profit mostly going to wealthy boat owners (Wildlife Conservation Society, unpubl. data). Controls enforced by the Panglima Laot on the use of nets therefore limit the perceived inequity by reducing competition among fishers of different economic status.
Many different socio-economic factors influence the ability of customary institutions to limit overexploitation of fishery resources. Generally, customary management systems operate best when the human population is low and distance to markets is great (Cinner & Aswani, Reference Cinner and Aswani2007; Aswani & Sabetian, Reference Aswani and Sabetian2010) Our findings suggest an opposite trend on Pulau Weh, where the proximity of a fishing location to a village and the number of people in the lhok probably assists the Panglima Laot to enforce compliance with fishing rules, because fishing activities are in view of local communities and there are more people to watch over the resource (Crawford et al., Reference Crawford, Siahainenia, Rotinsulu and Sukmara2004; McClanahan et al., Reference McClanahan, Verheij and Maina2006b).
The strong relationship between reef fish biomass and coral cover is not surprising because many reef fish rely on corals for shelter and food (Jones et al., Reference Jones, McCormick, Srinivasan and Eagle2004; Graham et al., Reference Graham, Wilson, Jennings, Polunin, Robinson, Bijoux and Daw2007). Numerous studies have reported declines in reef fish diversity and abundance following declines in coral cover and structural complexity (Jones et al., Reference Jones, McCormick, Srinivasan and Eagle2004; Pratchett et al., Reference Pratchett, Munday, Wilson, Graham, Cinner and Bellwood2008; Messmer et al., Reference Messmer, Jones, Munday, Holbrook, Schmitt and Brooks2011). This result suggests that one of the most effective means of protecting fish biomass is to protect the habitat. However, the positive correlation between fish biomass and the number of fishing gears prohibited also suggests that gear restrictions are having a direct effect by reducing fishing pressure. Reef fish biomass can be ten-fold greater in marine protected areas within 10 years of closure when compared to adjacent heavily fished areas (McClanahan & Graham, Reference McClanahan and Graham2005; Russ et al., Reference Russ, Stockwell and Alcala2005). Similarly, in a reef fishery in Tanzania the banning of dynamite, cyanide and small-mesh seine nets that are deployed in a similar manner to muroami nets on Pulau Weh also resulted in an increased abundance of reef fish and the biomass of some fish families (Tyler et al., Reference Tyler, Manica, Jiddawi and Speight2011). Although banning destructive fishing gears appears to be improving fish biomass on Pulau Weh and elsewhere (Tyler et al., Reference Tyler, Manica, Jiddawi and Speight2011) effort may need to be further limited to facilitate greater improvements in fish biomass. The Panglima Laot on the east coast of Pulau Weh have recently achieved this through the establishment of strict no-take areas within their marine waters. The proximity of a site to a village can shape reef fish biomass because of market-driven demands (Brewer et al., Reference Brewer, Cinner, Green and Pandolfi2009) and increased fishing pressure (Cinner & McClanahan, Reference Cinner and McClanahan2006). In contrast, our findings suggest the proximity of a fishing location to a village probably assists the Panglima Laot to enforce compliance with fishing rules, as described above.
Reef fish populations also vary in response to environmental factors such as wave exposure, currents and primary productivity (Halford et al., Reference Halford, Cheal, Ryan and Williams2004; Pratchett et al., Reference Pratchett, Munday, Wilson, Graham, Cinner and Bellwood2008). Although we did not specifically control for these environmental factors, the variation in reef fish biomass was much greater (up to eight-fold) than we would predict on the basis of environmental differences alone. Furthermore, adjacent lhoks (which have similar environments) with different levels of gear restriction (i.e. Ie Meulee vs Kota; Iboih–Kawasan Wisata vs Iboih–Panglima Laot, and Anoi Itam vs Keunekai) followed the general trend of greater fish biomass where the number of gears restricted was high.
Poor enforcement of controls on destructive fishing, including blast and cyanide fishing, may also be responsible for some of the differences in coral cover and fish biomass. According to local fishers, although blast fishing ceased in the 1990s, sporadic cyanide fishing continues in some lhoks such as Paya and Keunekai and may be contributing to consistently low coral cover and reef fish biomass at these sites.
The relative abundance of the different trophic groups was also linked to gear restrictions. The three lhoks where the most types of gears were prohibited (i.e. Anoi Itam, Ie Meulee and Iboih–Kawasan Wisata) were characterized by a greater biomass of corallivores, omnivores, herbivores, and to a lesser extent piscivores and planktivores, than lhoks where the number or gears prohibited was low (i.e., Iboih–Panglima Laot, Keunekai, Kota and Paya; Fig. 3). Similar responses following spatial closures on fishing of herbivorous parrot fish has been reported in the Indo-Pacific (Aswani & Sabetian, Reference Aswani and Sabetian2010).
The customary system of Panglima Laot has a number of the design principles identified by Ostrom (Reference Ostrom2009), and more recently examined by Gutierrez et al. (Reference Gutierrez, Hilborn and Defeo2011), to be associated with successful fisheries management institutions, including clearly defined membership rights, rules that limit resource use, the right of resource users to make, enforce and change the rules, graduated sanctions and a mechanism for conflict resolution (Cinner et al., Reference Cinner, Basurto, Fidelman, Kuange, Lahari and Mukminin2012). These principles are the key to the ability of the institution to reduce conflict among communities, provide sustainable access to marine resources and limit the destruction of marine habitats. However, the institution has not been uniformly successful. In particular, reef condition in the adjacent island group of Pulau Aceh was poor in 2005, possibly because of destructive fishing and poor coastal management (Baird et al., Reference Baird, Campbell, Anggorro, Ardiwijaya, Fadli and Herdiana2005; Campbell et al., Reference Campbell, Pratchett, Anggoro, Ardiwijaya, Fadli and Herdiana2007). The precise causes of this breakdown of the Panglima Laot system are the focus of current research efforts in the region. Investing a single individual with authority to make all decisions poses some risk of abuse.
Motivated by the aim of producing social harmony, restrictions on gear use by the Panglima Laot in Aceh have direct conservation benefits such as high coral cover and enhanced fish biomass. Additional surveys over a wider geographical scale and over a longer period are required to reveal whether these findings also apply at larger spatial and temporal scales.
Funding for this project was provided by The Kerzner Foundation and The National Fisheries and Wildlife Foundation. We acknowledge the Pulau Weh fishing communities for allowing us to use information on their socio-economic status. We also thank Dodent Mahyiddin from Rubiah Tirta Divers and Nur Fadli and Dr Edi Rudi from Syiah Kuala University, Banda Aceh, for their assistance and help with local logistics and knowledge.
Stuart Campbell's research interests include conservation biology. Joshua Cinner’s research explores how social, economic, and cultural factors influence the ways in which people use, perceive and govern natural resources, with a particular emphasis on using applied social science to inform coral reef management. Rizya Ardiwijaya designs and applies monitoring programmes to provide the ecological information necessary for the effective management of marine protected areas. Shinta Pardede's research interests include coral reef fish ecology. Tasrif Kartawijaya's research interests include the management of coral reef fisheries. Ahmad Mukmunin works to encourage dialogue between government and communities to promote coral reef conservation. He has been managing the Wildlife Conservation Society research programme in Aceh for 5 years. Yudi Herdiana's research interests include the ornamental fish trade. Andrew Hoey’s research interests include the functional importance of herbivorous fishes on coral reefs. Morgan Pratchett's research interests include the role of disturbance on coral reefs and the effect of climate change on fisheries. Andrew Baird's research interests include the evolution of life histories in corals. He has been engaging with the reefs of Aceh since 1984.