Detection of protection benefits for predatory fishes depends on census methodology

1. Marine protected areas (MPAs) are used as fisheries management and conservation tools. Well-enforced no-take zones allow the rebuilding of natural populations of exploited species; however, there is still controversy on the role of buffer zones.
2. The effectiveness of MPAs could be underestimated, as fish population assessments depend largely on traditional methodologies that have difficulties in detecting predatory fish because of their low abundances, their patchy distribution, and their reaction to the presence of divers.
3. The performance of different census methods was compared in assessing the protection benefits for large predatory fishes under different protection levels (i.e. no-take and buffer zones) in five Mediterranean MPAs. Specifically, conventional strip transects (CSTs, 50 × 5 m²) and tracked roaming transects combined with distance sampling (TRT + DS, variable lengths) were compared, including a series of TRT-derived estimators with variable transect lengths and fixed widths of 20, 10, and 6 m (TRT20, TRT10, and TRT6, respectively). Additionally, the effectiveness of the MPAs studied and protection levels for conserving large predatory species was evaluated.
4. Transects covering larger areas (i.e. TRT + DS and TRT20) allowed the detection of a greater number of species and yielded more accurate estimates of density and biomass than transects of narrower fixed widths, particularly the CSTs, which were associated with the lowest richness detection capability, accuracy, and precision. On average, both no-take zones and buffer zones appeared effective for the conservation of predatory fishes, indicating that multiple protection areas were ecologically effective. Differences between MPAs were also observed, however, probably arising from both local environmental and management factors.
5. We suggest the implementation of methodologies with larger transects for the study of large predatory fish, combined with CSTs for the rest of the fish community, in order to avoid biases in predatory population assessments, which are key indicators of MPA effectiveness.

     

Assessing spillover from marine protected areas and its drivers: A meta‐analytical approach

Overfishing may seriously impact fish populations and ecosystems. Marine protected areas (MPAs) are key tools for biodiversity conservation and fisheries management, yet the fisheries benefits remain debateable. Many MPAs include a fully protected area (FPA), restricting all activities, within a partially protected area (PPA) where potentially sustainable activities are permitted. An effective tool for biodiversity conservation, FPAs, can sustain local fisheries via spillover, that is the outward export of individuals from FPAs. Spillover refers to both: “ecological spillover”: outward net emigration of juveniles, subadults and/or adults from the FPA; and “fishery spillover”: the fraction of ecological spillover that directly benefits fishery yields and revenues through fishable biomass. Yet, how common is spillover remains controversial. We present a meta‐analysis of a unique global database covering 23 FPAs worldwide, using published literature and purposely collected field data, to assess the capacity of FPAs to export biomass and whether this response was mediated by specific FPA features (e.g. size, age) or species characteristics (e.g. mobility, economic value). Results show fish biomass and abundance outside FPAs was higher: (a) in locations close to FPA borders (<200 m) than further away (>200 m); (b) for species with a high commercial value; and (c) in the presence of PPA surrounding the FPA. Spillover was slightly higher in FPAs that were larger and older and for more mobile species. Based on the broadest data set compiled to date on marine species ecological spillover beyond FPAs' borders, our work highlights elements that could guide strategies to enhance local fishery management using MPAs.     

Evaluating the relative conservation value of fully and partially protected marine areas

The establishment of marine protected areas (MPAs), particularly of no‐take areas, is often viewed as a conflict between conservation and fishing. Partially protected areas (PPAs) that restrict some extractive uses are often regarded as a balance between biodiversity conservation and socio‐economic viability. Few attempts have been made to generalize the ecological effects of PPAs. We synthesized the results of empirical studies that compared PPAs to (i) no‐take reserves (NTRs) and (ii) to open access (Open) areas, to assess the potential benefits of different levels of protection for fish populations. Response to protection was examined in relation to MPA parameters and the exploitation status of fish. Our syntheses suggest that while PPAs significantly enhance density and biomass of fish relative to Open areas, NTRs yielded significantly higher biomass of fish within their boundaries relative to PPAs. The positive response to protection was primarily driven by target species. There was a large degree of variability in the magnitude of response to protection, although the size of the PPA explained some of this variability. The protection regime within the PPA provided useful insights into the effectiveness of partial MPAs. We conclude that MPAs with partial protection confer advantages, such as enhanced density and biomass of fish, compared to areas with no restrictions, although the strongest responses occurred for areas with total exclusion. Thus, MPAs with a combination of protection levels are a valuable spatial management tool particularly in areas where exclusion of all activities is not a socio‐economically and politically viable option.     

Characteristics of effective marine protected areas in Hawaiʻi

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Sharks,rays and marine protected areas: A critical evaluation of current perspectives

Marine protected areas (MPAs) are increasingly advocated for the conservation and management of sharks and rays. However, substantial uncertainty remains regarding which species can benefit from MPAs. Meanwhile, area‐focused protection targets have spurred recent and rapid gains in the creation of large MPAs, many of which carry vague objectives set by a diverse group of stakeholders with potentially different notions of “success.” Here, we capture and critically evaluate current views on the use of MPAs for shark and ray conservation. Through interviews with scientists, MPA managers, fisheries experts, conservation practitioners, advocates and policy experts (n = 53), we demonstrate a variety of perspectives regarding: (a) the effectiveness of MPAs as a tool for shark and ray conservation; (b) which factors influence the success of MPAs for sharks and rays; and (c) the desired outcomes of these MPAs. While MPAs created specifically for sharks and rays were viewed to be slightly more effective than regular MPAs as a tool for shark and ray conservation, both were generally considered insufficient in isolation. Despite greater emphasis on social success factors (e.g., local support) over biophysical success factors (e.g., size), biological outcomes (e.g., increased abundance) were prioritized over social outcomes (e.g., livelihood benefits). We argue that a stronger focus on achieving social outcomes can enhance the potential for MPAs to benefit sharks and rays. In revealing current thinking regarding the drivers and indicators of MPA success for sharks and rays, the results of this study can inform efforts to conserve and manage these species.     

Assessing the potential of marine Natura 2000 sites to produce ecosystem‐wide effects in rocky reefs: A case study from Sardinia Island (Italy)

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Effects of fisheries management on fish communities in the floodplain lakes of a Brazilian Amazonian Reserve

Abstract –  We compared fish abundance, diversity and species composition between lakes open (fished) and closed (no-take) to fishing activities in Mamirauá Sustainable Development Reserve in the Central Brazilian Amazon, in order to investigate potential influences of the common-based management. We sampled 1483 fishes from 70 species through gillnet fishing during the low-water season, in seven fished and seven no-take lakes. Contrary to expected, the mean values for abundance, size, diversity and species-richness of fish did not differ between fished and no-take lakes. There was no difference between fished and no-take lakes considering only the abundance of the 14 fish species more intensely targeted by fishermen. However, the abundance of an important commercial fish, the tambaqui ( Colossoma macropomum ) was higher in no-take lakes. Such data from a rapid assessment may be useful to monitor this and other fishery co-management schemes.     

Dynamics of fish assemblages on coral reefs subjected to different management regimes in the Abrolhos Bank,eastern Brazil

• 1. Marine protected areas (MPAs) range from multiple‐use areas (MUA) to absolute no‐take reserves (NTR). Despite their importance for fisheries management, there are few long‐term studies comparing benefits from different types of MPAs within the same region.
• 2. Fish assemblages were monitored for five years (2001–2005) in the largest coral reefs in the South Atlantic (Abrolhos Bank, Brazil). Monitoring included one community‐based MUA, two NTRs (one established in 1983 and another in 2001), and one unprotected area. Benthic assemblages at these areas, as well as fish assemblages on unprotected deeper reefs (25–35 m), were monitored from 2003 onwards.
• 3. Habitat characteristics strongly influenced fish assemblages' structure. This, together with the lack of data from before establishment of the MPAs, did not allow an unequivocal analysis of the effects of the MPAs.
• 4. Biomass of commercially important fish, particularly small carnivores, was higher in the older NTR. Biomass of black grouper Mycteroperca bonaci increased by 30‐fold inside NTRs during the study period, while remaining consistently low elsewhere.
• 5. A single herbivore species, the parrotfish Scarus trispinosus, dominated fish assemblages (28.3% of total biomass). Biomass of this species increased in 2002 on the younger NTR and on the MUA, soon after establishment of the former and banning of the parrotfish fishery in the latter. This increase was followed by a decline from 2003 onwards, after increased poaching and reopening of the parrotfish fishery.
• 6. Fish biomass increased in 2002 across the entire region. This increase was stronger in sites closer to deeper reefs, where fish biomass was up to 30‐times higher than shallow reefs: movement of fish from deeper to shallower areas may have played a role.
• 7. The effective use of MPAs in the Abrolhos Bank is still dependent on adequate enforcement and the protection of critical habitats such as deep reefs and mangroves.

Copyright © 2008 John Wiley & Sons, Ltd.     

Bridging the divide: Social–ecological coherence in Marine Protected Area network design

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Herbivorous fishes and the potential of Caribbean marine reserves to preserve coral reef ecosystems

• 1. The development of macroalgae to the detriment of corals is now one of the major threats to coral reefs. Herbivorous fishes are partly responsible for algal regulation on coral reefs and their overexploitation favours the shift from scleractinian coral‐dominated systems towards macroalgae‐dominated systems.
• 2. Marine protected areas (MPAs) that have been established worldwide may benefit coral reefs through the maintenance of high densities of herbivorous fishes which regulate algal growth.
• 3. The paper assesses whether small MPAs in the Caribbean are able to enhance herbivorous fish stock and by controlling macroalgae help to maintain reef ecosystems. A visual census using band‐transects was undertaken around Guadeloupe island where marine reserves have been in place since 1979. The effects of MPAs on both benthic communities and herbivorous fishes are examined.
• 4. Inside MPAs, herbivorous fish biomass was almost twice as high as outside MPAs and macroalgal cover was significantly lower. Fish size class distributions revealed that large individuals occurred mainly inside MPAs and that few male individuals were found outside MPAs. Copyright © 2010 John Wiley & Sons, Ltd.

     

Reserve effect of a small North-East Atlantic marine protected area (Arrábida,Portugal) on soft-sediment fish species

1. The implementation of marine protected areas (MPAs) has been widely used as a tool to manage and conserve marine resources and services. Yet, to date, the reserve effect is still weakly evaluated, particularly for soft-sediment habitats.
2. The Arrábida MPA, considered as a biodiversity hotspot, was fully established in 2009 on the west coast of Portugal and is characterized by large expanses of soft-sediment habitats. This MPA was established to protect biodiversity and to ensure the livelihood of the local small-scale fisheries community.
3. Beyond before–after-control–impact (BACI) analyses were carried out on catch data (abundance and biomass) of 351 trammel net sets from experimental fishing campaigns (2007–2019) to study the reserve effect on demersal fish populations.
4. The results show a declining trend in abundance inside and outside the protected area, with significant positive effects only found for undersize commercial species and Solea senegalensis, and a general increase in fish species total length. Despite the lack of any obvious reserve effect, the increase in fish length can be considered as a first sign.
5. Anthropogenic pressures are generalized around the area, and transgressions of the restrictions are frequently observed inside the no-take zone. These can, among other aspects, delay or prevent the expected reserve effects. Therefore, enforcement and/or modification of the spatial plan must be incentivized to achieve the goals of the MPA.

     

Drivers of consensus‐based decision‐making in international environmental regimes: Lessons from the Southern Ocean

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Assessing ecological changes in and around marine reserves using community perceptions and biological surveys

1. Well‐enforced partial or total no‐fishing zones (collectively known as marine protected areas, or MPAs) can help restore degraded coral reefs and enhance fish populations. 2. A comparison was made of community perceptions of ecological changes in an MPA with concurrent scientific data on these changes in the same MPA. Such analyses are particularly important in community‐based MPAs where local support is a key determinant of ecological success. 3. The no‐take MPA in question was initially launched in partnership with the community in 1995 and formalized in 1998. The perceptions data come from interviews with community members in 1999 and 2004, the biological data come from underwater visual censuses of the MPA from 1998 to 2004. 4. Community members perceived more fish within the MPA and slight increases in catch outside the MPA. In contrast, fish censuses showed a high degree of stochastic variation and only minor increases in fish abundance, size and diversity in and around the MPA between 1998 and 2004. 5. Possible explanations for these discrepancies include different temporal, spatial or species frames of reference and/or limitations to the biological survey technique. Other options include wishful thinking, external influences, a desire to please, or confounding with other benefits. 6. This study demonstrates some of the strengths and weaknesses of community perceptions and biological data. In order to improve our understanding about the changes that occur over time in an MPA and engender community support for the long‐term viability of MPAs, it is important to develop diverse and efficient monitoring schemes. Copyright © 2010 John Wiley & Sons, Ltd.     

Progress,opportunities and challenges for marine conservation in the Pacific Islands

1. The people of the Pacific have long relied on the ocean for sustenance, commerce and cultural identity, which resulted in a sophisticated understanding of the marine environment and its conservation.
2. The global declines in ocean health require new and innovative approaches to conserving marine ecosystems. Marine Protected Areas (MPAs) have been shown to be a highly effective means of conserving biodiversity and managing fisheries, while also restoring and preserving overall ecosystem function.
3. Traditional ecological knowledge held by many island peoples in the Pacific is critical to the development, design and implementation of contemporary MPAs.
4. Chile's offshore islands are among the few oceanic archipelagos along the west coast of South America. These islands have cultural and ecological connections to the broader insular Pacific, yet our scientific understanding of them is extremely limited.
5. Chile has created several large-scale MPAs around their offshore archipelagos. By protecting these unique ecosystems, Chile has established itself as a global leader in marine conservation.
6. Effective management and a better understanding of social–ecological interactions are currently the biggest challenges facing MPAs in the Pacific Islands.

     

Evaluating the efficacy of small‐scale marine protected areas for preserving reef health: A case study applying emerging monitoring technology

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Attending to spatial social–ecological sensitivities to improve trade‐off analysis in natural resource management

Balancing trade‐offs amongst social–ecological objectives is a central aim of natural resource management. However, objectives and resources often have spatial dimensions, which are usually ignored in trade‐off analyses. We examine how simultaneously integrating social–ecological benefits and their spatial complexities can improve trade‐off analysis. We use Pacific herring (Clupea pallasii, Clupeidae)—an ecologically important forage fish with social, cultural and economic value to communities and commercial fisheries—as a case study. By combining spatial management strategy evaluation with social benefits analysis, we illustrate when policies aimed at aggregate stocks versus spatially segregated substocks of fish fail to balance trade‐offs amongst social–ecological objectives. Spatial measures (e.g. area‐based closures) may achieve some objectives but produce alternative trade‐offs that are sensitive to assumptions about fish population dynamics and social complexities. Our analyses identify policies that are inefficient (e.g. yielding economic costs without producing social or ecological gains), highlight management strategies that generate trade‐offs and indicate when costs are distributed unequally for different user groups. We also point to strategies with outcomes that are robust to spatial uncertainties and reveal research priorities by identifying which performance metrics exhibit sensitivity to spatial ecological assumptions. Collectively, our analyses demonstrate how incorporating social objectives and spatial dynamics into management strategy evaluation can reveal trade‐offs and the implications of management decisions.     

Interactions between the implementation of marine protected areas and right-based fisheries management in Australia

Abstract  The declaration of marine protected areas (MPAs) in Australia generates much confusion and controversy between government conservation and fisheries agencies, the fishing industry and NGOs. There are fundamental differences between the principles and practices underpinning the implementation of MPAs and fisheries management. This paper analyses the interactions between these two approaches to natural resource management and highlights the difficulties in integrating them effectively. The major challenges for governments are: poor cooperation between fisheries and conservation agencies; in principle inconsistencies between allocation of fishing rights by fisheries agencies and loss of these rights through MPA declaration; re-allocation of resources between user groups through spatial zoning; lack of fisheries expertise in conservation planning, and inappropriate single-species/single-issue approach to fisheries management. As fisheries agencies are now considering developing their own MPAs as tools for fisheries management, the need to address inconsistencies between conservation and fisheries approaches to the spatial management of natural resources increases further. Better collaboration between government agencies and better coordination of their activities would help more effective and less conflicting management of marine resources.     

Implications of fish migration and fishing mortality for marine protected area design

The Convention on Biological Diversity calls for networks of ‘representative’ MPAs, the effectiveness of which requires that the protected ecosystems be independent of external anthropogenic pressures. One principal pressure, fishing, severely depletes the oldest age classes of the target fish even if optimally managed. As many fishery resource species had high natural abundance and large individual sizes, while most fish show indeterminate growth and ascend the trophic pyramid as they grow, elimination of older age classes equates to removal of once‐dominant top predators. Because archetypal resource species are also migratory, that loss is transported throughout the range of the exploited populations, including into MPAs, through a lack of large migrants. The ecological implications remain uncertain in marine ecosystems, which are typically under ‘bottom‐up’ control. ‘Top‐down’ effects, such as mesopredator release, species replacement and trophic cascades, have been observed, however, meaning that elimination of top predators may affect ecosystem structure. It follows that, while exceptions doubtless exist, in general ‘representative’ MPAs should not be expected to fulfil their declared purposes, unless they are made so large as to encompass the whole migratory circuits of principal resource species – implying indefinite closure of the fisheries affected. Some compromise may be possible if MPAs were combined with fishing mortality rates far below current ‘optimal’ levels or where fishing can be concentrated on younger adults, while older fish are protected from exploitation. In any case, societies must choose between seafood production and recovery of selected marine areas to near‐pristine conditions.