Management Of Coral Reef Fisheries Research Articles

Fish community structure and dynamics are insufficient to mediate coral resilience.

Coral reefs are being impacted by myriad stressors leading to drastic changes to their structure and function. Fishes play essential roles in driving ecosystem processes on coral reefs but the extent to which these processes are emergent at temporal or ecosystem scales or otherwise masked by other drivers (for example, climatic events and crown-of-thorns starfish outbreaks) is poorly understood. Using time series data on fish community composition and coral and macroalgae percentage cover between 2006 and 2017 from 57 sites around Mo'orea, Polynesia, we found that fish community diversity predicts temporal stability in fish biomass but did not translate to temporal stability of coral cover. Furthermore, we found limited evidence of directional influence of fish on coral dynamics at temporal and ecosystem scales and no evidence that fish mediate coral recovery rate from disturbance. Our findings suggest that coral reef fisheries management will benefit from maintaining fish diversity but that this level of management is unlikely to strongly mediate coral loss or recovery over time.

Climate change disturbances contextualize the outcomes of coral-reef fisheries management across Micronesia

Climate change is increasing disturbance events on coral reefs with poorly understood consequences for fish population dynamics and fisheries management. Given growing concerns over food security for the tropical Pacific, we assessed fisheries management policies across a suite of Micronesian islands since 2014 as climate disturbance events have intensified. Disturbances associated with the 2015–2017 ENSO led to significant mortality of corals and calcifying substrates and replacement with algae and detritus, followed by a doubling of biomass across all fish guilds that was proportional to their starting points for all islands. Increased fish biomass was equally attributed to growth of individuals evidenced by increased size structures, and recruitment/survival evidenced by larger population densities. However, the pulsed increase of fish biomass lasted 1–2 years for islands with limited and isolated MPA but remained high for islands with effective MPA networks for 4 years until the study ended. Meanwhile, policies to protect grouper spawning seasons resulted in increased occurrences that were magnified by disturbances and MPA. Grouper increases were largest where both spawning season bans and MPA networks existed, helping to tease apart the management-from-disturbance responses. Smaller rates of increases over longer time were observed for species with commercial fishing bans (bumphead parrotfish, Napoleon wrasse, and sharks). Yet, occurrences remain low in comparison to remote-island baselines, and MPA only provided benefits for juveniles in inner lagoons. Recent trends for these species were less influenced by climate disturbances compared to groupers. The results cautioned how short-term responses of fish assemblages following climate disturbances can provide false signs of success for some management policies without contextual reference baselines that may not exist. Positively, improvements were noted for both MPA and species policies in our region that are expected to benefit reef resilience.

SUSTAINABILITY WINDOW APPROACH FOR FISHERIES MANAGEMENT AT THE COASTAL AREA OF TERNATE ISLAND, NORTH MALUKU PROVINCE

Aims: This study aims to assess the value sustainable development opportunity of the coral reef fisheries activities in Indonesia from the ecological, economic, and social aspect, with a case study of coral reef fisheries at the coastal area of Ternate Island, using the Sustainability Window (SuWi) approach. Methodology and Results: The data was collected from statistical data from relevant institutions and literature study, which consists of ecological, economic and social data, and analyzed using the Sustainability Window approach to determine the sustainability of the fisheries development. The result shows that the Sustainability Window of the coral reef fisheries in the research area tends to move towards sustainable development, where the national policy in catch fisheries management has an impact on the sustainable development and management of coral reef fisheries at the coastal area of Ternate Island. Conclusion, significance and impact study: The Sustainability Window of coral reef fisheries at the coastal area of Ternate Island tends to move towards sustainable processes, with the width of sustainability window that not too narrow to the coral reef fisheries activities at the provincial and national levels. This condition attaches strings to a precautionary approach in policy decision for the management process, and consideration to the effect that can result from the development policy, both at the provincial and national level. The use of Sustainability Windows approach can provide a new simple way for assessing whether the development has been towards a more sustainable direction or not.

Contextualizing the social-ecological outcomes of coral reef fisheries management

Marine protected areas (MPAs) have emerged as a valuable tool in biodiversity conservation and fisheries management. However, the effective use of MPAs depends upon the successful integration of social and ecological information. We investigated relationships between the social system structure of coastal communities alongside biological data describing the status and trends in fish communities around Yap, Micronesia. Traditional marine tenure made Yap an ideal place to investigate the underlying principles of social-ecological systems, as communities own and manage spatially-defined coastal resources. Analysis of social survey data revealed three social regimes, which were linked to corresponding gradients of ecological outcomes. Communities with decentralized decision-making and a preference for communal forms of fishing had the greatest ecological outcomes, while communities lacking any form of leadership were linked to poor ecological outcomes. Interestingly, communities with strong top-down leadership were shown to have variable ecological outcomes, depending on the presence of key groups or individuals. We last investigated whether social perception could successfully predict the status of fish assemblages within non-managed reefs. Several biological metrics of fish assemblages within non-managed areas were significantly predicted by a gradient of human access, suggesting social perception could not predict the growing human footprint over the study period. These findings highlight the potentially overlooked role that community-oriented decision-making structures and fishing methods could play in successful conservation efforts, and the limitations of perception data. Policies that promote communal marine resource use offer a novel approach to improve fisheries management and promote social-ecological resilience.

Effectiveness of small locally-managed marine protected areas for coral reef fisheries management in the Philippines

The Philippines has more than 1600 locally managed marine protected areas (MPAs), the most in the world. However, their effectiveness for coral reef fisheries management is often questionable because most of these MPAs are small and ineffectively managed. In this study, we assessed the fish biomass of commercially important coral reef fishes (e.g. surgeonfish (family Acanthuridae), parrotfish (subfamily Scarinae), snapper (family Lutjanidae), grouper (subfamily Epinephelinae), sweetlips (family Haemulidae), goatfish (Mullidae) and emperor (family Lethrinidae)) in 57 locally managed MPAs in the Philippines. We used the fish biomass level at the nationally managed, large (332.0 km2), remote, old and well enforced (i.e. strictly protected for >20 years) Tubbataha Reefs National Marine Park (TRNMP) as a proxy for “unfished” ecosystems (Bo). We considered fish biomass levels between 25 and 50% of Bo as biomass within the maximum sustainable yield for multi-species coral reef fisheries (BMMSY) (McClanahan et al., 2014). Results showed that fish biomass levels in 7%, 25% and 68% of the surveyed MPAs were “above BMMSY”, “within BMMSY” and “below BMMSY”, respectively. None of the reefs outside MPAs was “above BMMSY”. About 86% were “below BMMSY” and the rest of the 14% of the sites outside MPAs were “within BMMSY” (14%). The mean (±S.E.) fish biomass levels on reefs inside and outside MPAs were only about 20.4 ± 2.2% and 10.9 ± 1.3%, respectively, of the TRNMP level. Neither size nor age of MPAs was significantly associated with fish biomass. Overall, our study showed that the current locally managed MPAs are not effective enough for coral reef fisheries management but, nonetheless, better than having no MPA at all.

Maneuvering towards adaptive co-management in a coral reef fishery

Tropical coral reef ecosystems in the Pacific region are degrading rapidly as ocean temperatures rise and local anthropogenic stressors increase. In this context of rapid change, effective site-based management of coral reef fisheries necessitates flexible environmental governance that is closely attuned to the needs of multiple stakeholders who depend on the fishery for income, food, and cultural identity. As such, many practitioners and scholars call for adaptive co-management of coral reef fisheries where local resource users play a primary role in environmental governance with the support of flexible institutions that operate across organizational scales. This article describes the history and evaluates the current status of marine governance in Moorea, French Polynesia. Established in 2004, the management framework is under revision because it has failed to meet its ecological objectives and has generated discontent among many stakeholders. Drawing on household surveys, interviews, and archival information, the challenges to as well as the factors that may enable a more successful transition of the current governance arrangement towards co-management are detailed. It is argued that recent social mobilization, subsistence and cultural links to the fishery, the presence of geographically and socially relevant traditional governance boundaries, and the implementation of co-management in other parts of French Polynesia are positive factors. However, lack of trust between stakeholders, social heterogeneity, disruption of traditional cultural institutions and practices, minimal institutional support, and an uncertain legal framework suggest that there are significant headwinds for maneuvering towards successful co-management in Moorea.

Local Biomass Baselines and the Recovery Potential for Hawaiian Coral Reef Fish Communities

Understanding the influence of multiple ecosystem drivers, both natural and anthropogenic, and how they vary across space is critical to the spatial management of coral reef fisheries. In Hawaii, as elsewhere, there is uncertainty with regards to how areas should be selected for protection, and management efforts prioritized. One strategy is to prioritize efforts based on an area’s biomass baseline, or natural capacity to support reef fish populations. Another strategy is to prioritize areas based on their recovery potential, or in other words, the potential increase in fish biomass from present-day state, should management be effective at restoring assemblages to something more like their baseline state. We used data from 717 fisheries-independent reef fish monitoring surveys from 2012-2015 around the main Hawaiian Islands as well as site-level data on benthic habitat, oceanographic conditions, and human population density, to develop a hierarchical, linear Bayesian model that explains spatial variation in: (1) herbivorous and (2) total reef fish biomass. We found that while human population density negatively affected fish assemblages at all surveyed areas, there was considerable variation in the natural capacity of different areas to support reef fish biomass. For example, some areas were predicted to have the capacity to support ten times as much herbivorous fish biomass as other areas. Overall, the model found human population density to have negatively impacted fish biomass throughout Hawaii, however the magnitude and uncertainty of these impacts varied locally. Results provide part of the basis for marine spatial planning and/or MPA-network design within Hawaii.

Ecological indicators for coral reef fisheries management

AbstractCoral reef fisheries are of great importance both economically and for food security, but many reefs are showing evidence of overfishing, with significant ecosystem‐level consequences for reef condition. In response, ecological indicators have been developed to assess the state of reef fisheries and their broader ecosystem‐level impacts. To date, use of fisheries indicators for coral reefs has been rather piecemeal, with no overarching understanding of their performance with respect to highlighting fishing effects. Here, we provide a review of multispecies fishery‐independent indicators used to evaluate fishing impacts on coral reefs. We investigate the consistency with which indicators highlight fishing effects on coral reefs. We then address questions of statistical power and uncertainty, type of fishing gradient, scale of analysis, the influence of other variables and the need for more work to set reference points for empirical, fisheries‐independent indicators on coral reefs. Our review provides knowledge that will help underpin the assessment of the ecological effects of fishing, offering essential support for the development and implementation of coral reef fisheries management plans.

Thresholds in Caribbean coral reefs: implications for ecosystem‐based fishery management

Summary Ecosystem‐based management of coral reef fisheries aims to sustainably deliver a diverse portfolio of ecosystem services. This goal can be undermined if the ecosystem shifts into a different state, with altered ecosystem functions and benefits to people. If levels of drivers that cause transitions between states are identified, management measures could be aimed at maintaining drivers below these levels to avoid ecosystem shifts. Analysing data from a large number of Caribbean coral reefs (N = 2001), suites of nonlinear thresholds were identified between metrics of coral reef processes and structure along a gradient of total fish biomass (a proxy for fishing pressure). Several metrics (macroalgal cover, invertivorous fishes and fish species richness) associated with coral‐dominated reefs exhibited thresholds at relatively high fish biomass levels (50–88% of unfished biomass). Other metrics (urchin biomass, ratio of macroalgal to coral cover, herbivorous fishes and coral cover) showed thresholds at lower fish biomass levels (28–37% of unfished biomass). Ratios of total fish biomass in fishing areas to closed areas (unfished biomass) in the Caribbean indicate that reefs may generally be at risk for change at ratios between 0·5 (coral dominated) and 0·3 (macroalgal dominated). Similar relationships were found for coral reefs in the Indian Ocean. While these results illustrate thresholds at the scale of the entire Caribbean, assessing local reefs is advisable because biomass levels vary within the region, and reef trajectories depend on past, present and future local conditions. Synthesis and applications. If the thresholds in this study are generalizable to scales relevant to management, it may be possible to produce sustainable yield while simultaneously maintaining coral‐dominated reefs by restricting fishing mortality to levels that result in biomass ratios near 0·5. Fishing down to biomass ratios near 0·3 may increase the risk of overfishing (resulting in lower long‐term yields) and transition to macroalgal‐dominated reefs. Thresholds offer a simple and powerful way for managers to operationalize precautionary ecosystem‐based fishery management by adaptively limiting fishing pressure in order to (i) maintain desirable coral reef conditions, (ii) establish a system‐specific target for generating pretty good yield and (iii) maintain sustainable multi‐species fishery yields.

Biomass-based targets and the management of multispecies coral reef fisheries.

The failure of fisheries management among multispecies coral reef fisheries is well documented and has dire implications for the 100 million people engaged in these small-scale operations. Weak or missing management institutions, a lack of research capacity, and the complex nature of these ecosystems have heralded a call for ecosystem-based management approaches. However, ecosystem-based management of coral reef fisheries has proved challenging due to the multispecies nature of catches and the diversity of fish functional roles. We used data on fish communities collected from 233 individual sites in 9 western Indian Ocean countries to evaluate changes in the site's functional composition and associated life-history characteristics along a large range of fish biomass. As biomass increased along this range, fish were larger and grew and matured more slowly while the abundance of scraping and predatory species increased. The greatest changes in functional composition occurred below relatively low standing stock biomass (<600 kg/ha); abundances of piscivores, apex predators, and scraping herbivores were low at very light levels of fishing. This suggests potential trade-offs in ecosystem function and estimated yields for different management systems. Current fishing gear and area restrictions are not achieving conservation targets (proposed here as standing stock biomass of 1150 kg/ha) and result in losses of life history and ecological functions. Fish in reefs where destructive gears were restricted typically had very similar biomass and functions to young and low compliance closures. This indicates the potentially important role of fisheries restrictions in providing some gains in biomass and associated ecological functions when fully protected area enforcement potential is limited and likely to fail. Our results indicate that biomass alone can provide broad ecosystem-based fisheries management targets that can be easily applied even where research capacity and information is limited. Of particular value, is our finding that current management tools may be used to reach key ecosystem-based management targets, enabling ecosystem-based management in many socioeconomic contexts.

Re-estimation and synthesis of coral-reef fishery landings in the Commonwealth of the Northern Mariana Islands since the 1950s suggests the decline of a common resource

Coral-reef fisheries play a central role in Pacific Island societies for their cultural, subsistence and economic values. Despite their importance, management of coral reef fisheries continues to be hampered by difficulties in estimating accurate fish landings. This study focuses upon both commercial and non-commercial reef-fish landings in the Commonwealth of the Northern Mariana Islands (CNMI), using existing and new datasets derived from catch-based records and household interviews. We found that previous estimations of CNMI’s non-commercial reef-fish landings were rooted in a common misinterpretation of a key historical study that led to very low reported contributions from the non-commercial reef-fishing sector. Present evidence introduced from socioeconomic surveys suggested that non-commercial fisheries were between five and nine times commercial counterparts in the mid-2000s. Further, we introduce new commercial landing datasets based upon required reporting to CNMI’s Nutritional Assistance Program that appeared to offer improved estimates of reef-fish landings compared with an existing voluntary reporting system that has been in place since the late 1970s. Using an influential anchor point in the 1950s, we synthesize that modern reef-fish landings in CNMI are, at best, similar to those conservatively estimated for the past, with more likely scenarios suggesting a 39–73 % decline since the 1950s. These findings are consistent with a body of literature suggesting reduced catch success through time and negative impacts to coral reefs in proximity to population centers. Ongoing data collection improvements are needed to ensure accurate assessments of CNMI’s coral-reef fishery and sound fisheries policies.

Time preferences and the management of coral reef fisheries

To investigate a potential relationship between financial and marine resource use decisions, we conducted a time preference experiment with 153 fishers and 197 SCUBA divers on Curaçao and Bonaire. The experiment was part of a socioeconomic survey wherein interviewees were asked about their fishing and diving practices, views on fish population and coral reef health, and preferred marine resource management approaches. We use a βδ-model to identify discounting and present bias. Divers had a mean individual discount factor (IDF) of 0.91, significantly higher than fishers' mean of 0.82. Fishers and divers had similar distributions of IDFs and present bias; overall 66% of interviewees were non-biased, 22% future-biased, and 12% present-biased. IDFs and present bias were able to predict management preferences after controlling for demographic factors. However, the effect of discount factors is unique to divers, and the effect of present bias is concentrated among fishers on Curaçao. Differences in time preferences between fishers and divers should be considered when developing management strategies. Transfer payments from the dive industry could facilitate a transition to sustainable fishing practices. Establishing property rights alone may not be sufficient for ensuring sustainability if fishers are present-biased and greatly discount the future.

Effects of Human Population Density and Proximity to Markets on Coral Reef Fishes Vulnerable to Extinction by Fishing

Coral reef fisheries are crucial to the livelihoods of tens of millions of people; yet, widespread habitat degradation and unsustainable fishing are causing severe depletion of stocks of reef fish. Understanding how social and economic factors, such as human population density, access to external markets, and modernization interact with fishing and habitat degradation to affect fish stocks is vital to sustainable management of coral reef fisheries. We used fish survey data, national social and economic data, and path analyses to assess whether these factors explain variation in biomass of coral reef fishes among 25 sites in Solomon Islands. We categorized fishes into 3 groups on the basis of life-history characteristics associated with vulnerability to extinction by fishing (high, medium, and low vulnerability). The biomass of fish with low vulnerability was positively related to habitat condition. The biomass of fishes with high vulnerability was negatively related to fishing conducted with efficient gear. Use of efficient gear, in turn, was strongly and positively related to both population density and market proximity. This result suggests local population pressure and external markets have additive negative effects on vulnerable reef fish. Biomass of the fish of medium vulnerability was not explained by fishing intensity or habitat condition, which suggests these species may be relatively resilient to both habitat degradation and fishing.

Critical thresholds and tangible targets for ecosystem-based management of coral reef fisheries

Sustainably managing ecosystems is challenging, especially for complex systems such as coral reefs. This study develops critical reference points for sustainable management by using a large empirical dataset on the coral reefs of the western Indian Ocean to investigate associations between levels of target fish biomass (as an indicator of fishing intensity) and eight metrics of ecosystem state. These eight ecological metrics each exhibited specific thresholds along a continuum of fishable biomass ranging from heavily fished sites to old fisheries closures. Three thresholds lay above and five below a hypothesized window of fishable biomass expected to produce a maximum multispecies sustainable yield (B(MMSY)). Evaluating three management systems in nine countries, we found that unregulated fisheries often operate below the B(MMSY), whereas fisheries closures and, less frequently, gear-restricted fisheries were within or above this window. These findings provide tangible management targets for multispecies coral reef fisheries and highlight key tradeoffs required to achieve different fisheries and conservation goals.

Changes in life history and ecological characteristics of coral reef fish catch composition with increasing fishery management

Abstract Length, life history and ecological characteristics of landed fish communities were studied over a 10‐year period to test theories of fishing disturbance during a time of increased gear and closure management in heavily utilised fisheries. It was predicted that with greater management restrictions: (1) the earliest and fastest responses in the fishery will be seen in those species with faster turnovers, or relatively lower vulnerabilities to fishing; (2) the fishery would transition to a landed catch with higher mean trophic levels, and greater mean body lengths. In addition, the removal of a non‐selective, small‐mesh seine nets should benefit the catch of gears that previously had the greatest species selectivity overlap with the seine net. Many predictions were supported, although maximum lengths and lengths at maturity responded more rapidly than anticipated. The response to eliminating the non‐selective seine net was a more rapid increase in sizes caught by gears with a larger overlap in size (hook and lines) than species selectivity (gill nets). The simultaneous comparison of management systems over time indicates that open‐access fishing grounds can benefit from restrictions imposed in adjacent fishing grounds. The study indicated that multi‐species coral reef fisheries management objectives of maximising yields, as well as maintaining the fish community’s life‐history diversity, require management trade‐offs that balance local socio‐economic and biodiversity needs.

Using very high resolution remote sensing for the management of coral reef fisheries: Review and perspectives

Coral reef fisheries are critical for food security and as a source of income in developing and developed countries, but they are collapsing in many areas. Following the emergence and routine availability of commercial very high spatial resolution (0.6–10m) multispectral satellite images, we reviewed the use of these new high-quality remote sensing data and products for coral reef fisheries management. The availability of habitats maps improves management by guiding sampling strategies, mapping resources, involving local communities, identifying conservation areas, and facilitating Ecosystem Based Fishery Management (EBFM) approaches. However, despite their potential, very little use of products designed specifically for fishery management can be reported, likely due to high costs, inherent technology limitations and lack of awareness on the possibilities. Given the theoretical benefits brought by relevant habitat maps in EBFM frameworks, we advocate the use of adequate remote sensing products that integrate fishery technical services demands and local requirements.

Towards multidisciplinary indicator dashboards for coral reef fisheries management

The diversity of reef ecosystems, the multiplicity of reef resource uses and the breadth of the range of the island socio-cultural contexts concerned make coral reef fisheries (CRF) management in the South Pacific a complex task. The health and state of the targeted resources depend both on ecosystem characteristics (as determined by ecolog- ical and biological factors) and on fishing pressure, whose effects are only partly known. Increasing harvests from com- mercial and recreational fishing increasingly overlap with traditional subsistence activity, creating an important CRF management challenge. This paper presents a new approach to CRF assessment and monitoring by providing a set of multidisciplinary indicators. The fisheries system is assessed from three different viewpoints: ecology of targeted popu- lations, exploitation and the broader socio-economic fishery context. The use of complementary indicators chosen from each of these fields could balance the chronic lack of human and financial resources for the management of these fish- eries. We suggest the use of these indicators through an assessment grid or an indicator dashboard specifically adapted to given situations and management objectives determined through a participatory approach. The operational efficiency of this dashboard depends on i) dialogue between users, ii) the objectivity of the proposed monitoring, iii) the visual transcription of divergent/convergent interests amongst stakeholders, and iv) stakeholder involvement in the decision- making process. The use and constraints of such a tool are described with reference to Ouvea atoll (New-Caledonia, South Pacific) for which an analysis of available indicators for assessing fisheries status is presented.

Marine Reserves: Rates and Patterns of Recovery and Decline of Large Predatory Fish

A major objective of the use of marine reserves in management of coral reef fisheries is protection of a critical spawning stock biomass to ensure recruitment supply to fished areas via larval dispersal. However, very little empirical evidence exists on the rates and patterns of increase of density and biomass of target species following the closure of a coral reef or part of a reef, nor on how quickly any gains potentially useful to fisheries can be lost if reserves are subsequently opened to fishing. This paper presents empirical evidence derived from the visual monitoring of density and biomass of large predatory coral reef fish (Serranidae (Epinephelinae), Lutjanidae, Lethrinidae and Carangidae as a group) in two small marine reserves and at two control sites in the Philippines from 1983 to 1993. At one reserve (Sumilon) a complex history of management allowed seven measurements of density and biomass at durations of reserve protection ranging from ‐2 (i.e., fished for 2 yr) to 9 yr. At the second reserve (Apo), seven measurements were taken at durations of reserve protection ranging from 1 to 11 yr. Density of large predators provided an excellent indicator of the effects of marine reserve protection and fishing. Density decreased significantly twice when the Sumilon reserve was opened to fishing (1985, 1993), and increased significantly three times following durations of marine reserve protection of 5 yr (Sumilon reserve and nonreserve sites, 1987‐1991) and &gt;6 yr (Apo reserve beyond 1988). Density of large predators at the Apo nonreserve site (open to fishing) did not change significantly, remaining low throughout the study. Significant positive linear correlations of mean density of large predators with years of reserve protection were observed at both reserves. The rates of increase were 1.15 and 0.72 fish·1000 m‐2·yr‐1 at Sumilon and Apo reserves, respectively, with mean density ranges of ≈ 4‐17 fish/1000 m2 (‐2 to 9 yr of protection) at Sumilon and 0.5‐9.5 fish/1000 m2 (1‐11 yr of protection) at Apo. The pattern of increase of mean biomass with years of reserve protection was more curvilinear than that of mean density, particularly at Sumilon, where a slow increase was observed in the first 3‐5 yr (reflecting delayed recruitment and a natural delay to the period of maximum individual mass growth), followed by an increasing rate over the next 4 yr. Mean biomass ranges were ≈ 1.5‐18 kg/1000 m2 (‐2 to 9 yr of protection) at Sumilon and 1‐10.5 kg/1000 m2 (1‐11 yr of protection) at Apo. At Sumilon reserve, 2 and 1.5 yr of unregulated fishing, respectively, eliminated density and biomass gains accumulated over 5 and 9 yr of marine reserve protection.