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Marine protected areas (MPAs) are an essential tool for reversing the global degradation of ocean life. Hence, it is important to know which types of MPAs are more effective, and under which conditions. No-take marine reserves – the MPAs with stronger protection – are very effective in restoring and preserving biodiversity, and in enhancing ecosystem resilience. A new meta-analysis of previous studies shows that bio-mass of whole fish assemblages in marine reserves is, on average, 670% greater than in adjacent unprotected areas, and 343% greater than in partially-protected MPAs. Marine reserves also help restore the complexity of ecosystems through a chain of ecological effects (trophic cascades) once the abundance of large animals recovers sufficiently. Marine reserves may not be immune to the effects of climate change, but to date, reserves with complex ecosystems are more resilient than unprotected areas. Although marine reserves were conceived to protect ecosystems within their boundaries, they have also been shown to enhance local fisheries and create jobs and new incomes through ecotourism.
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Food for Thought
No-take marine reserves are the most effective protected areas
in the ocean
Enric Sala
* and Sylvaine Giakoumi
National Geographic Society, 1145 17
St NW, Washington, DC 20036, USA
Universite´Coˆte d’Azur, CNRS, ECOMERS FRE 3729, 28 Valrose Avenue, Nice, France
*Corresponding author: e-mail:
Sala, E., and Giakoumi, S. 2017. No-take marine reserves are the most effective protected areas in the ocean. – ICES Journal of Marine Science,
Received 16 February 2017; revised 11 March 2017; accepted 16 March 2017.
Marine protected areas (MPAs) are an essential tool for reversing the global degradation of ocean life. Hence, it is important to know which
types of MPAs are more effective, and under which conditions. No-take marine reserves – the MPAs with stronger protection – are very effec-
tive in restoring and preserving biodiversity, and in enhancing ecosystem resilience. A new meta-analysis of previous studies shows that bio-
mass of whole fish assemblages in marine reserves is, on average, 670% greater than in adjacent unprotected areas, and 343% greater than in
partially-protected MPAs. Marine reserves also help restore the complexity of ecosystems through a chain of ecological effects (trophic cas-
cades) once the abundance of large animals recovers sufficiently. Marine reserves may not be immune to the effects of climate change, but to
date, reserves with complex ecosystems are more resilient than unprotected areas. Although marine reserves were conceived to protect eco-
systems within their boundaries, they have also been shown to enhance local fisheries and create jobs and new incomes through ecotourism.
Keywords: ecosystem restoration, marine conservation, marine protected areas, marine reserves, resilience.
As of March 2017, 3.5% of the ocean was within implemented
“Marine Protected Areas” (MPAs), and only 1.6% was in strongly
protected (no-take) MPAs (Lubchenco and Grorud-Colvert,
2015). Despite the recent increase in large MPAs worldwide, we
are still short of the United Nations target of 10% of the ocean
protected by 2020. Although MPAs are a key tool for ocean con-
servation, there is some uncertainty regarding when and where
MPAs are most effective (Woodcock et al., 2016). Here, we show
that no-take MPAs are very effective in restoring and preserving
the ecosystems they are designed to protect from human
What’s a marine protected area?
There are many MPA definitions, but in summary, MPAs are
areas that are intended to protect all or part of a marine ecosys-
tem. At the most protective end of the spectrum are no-take “ma-
rine reserves” – areas where extractive activities are prohibited.
The rest are “partially protected MPAs” that allow extractive ac-
tivities to different degrees. Here we will distinguish between
these two groups (NCEAS, 2001;Lubchenco and Grorud-Colvert,
2015) and discuss only areas whose goal is to protect and restore
marine biodiversity.
How effective are MPAs?
First, we need to define why are MPAs created. As originally con-
ceived, the main goal of MPAs is to protect and restore biodiver-
sity within their boundaries. “Biodiversity” ranges from species
richness and abundance to the structure of ecosystems (Sala and
Knowlton, 2006).
The fish come back
A meta-analysis of scientific studies (Supplemental online mate-
rial) shows that the biomass of the whole fish assemblage is, on
average, 670% greater within marine reserves than in unprotected
areas, and 343% greater than in partially-protected MPAs
(Figure 1). Fish biomass in partially protected MPAs was only
183% greater than in unprotected areas, and often it was not
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different from unprotected areas (e.g. Aburto-Oropeza et al.,
2011). In addition, fish biomass was restored in marine reserves
over time after protection, but not in partially-protected MPAs or
unprotected areas (Figure 2).
What about the rest of the ecosystem?
Marine reserves can cause indirect effects that restore the struc-
ture and complexity of the ecosystem as it was before overexploi-
tation – once predator abundance recovers sufficiently. For
example, in the Mediterranean and New Zealand, sea urchin
predators reduce sea urchin density and consequently have
shifted the ecosystem from a degraded state (sea urchin barren)
to a complex, healthy state (algal forests with high biodiversity)
(Shears and Babcock, 2003;Guidetti and Sala, 2007). Initial de-
tection of effects on target species was 5 years on average, but de-
tection of indirect effects on other taxa (e.g. sea urchins, abalone,
algae) took 13 years (Babcock et al., 2010). In tropical seas, unf-
ished reefs with very large fish biomass also tend to be associated
with greater coral coverage and less coral disease than fished reefs
(Sandin et al., 2008), and a microbial ecosystem with less bacteria,
viruses and pathogens (Dinsdale et al., 2008). Such effects are not
so apparent in places like the Caribbean, however, because most
marine reserves have not achieved yet a sufficient abundance of
large fishes to exert their significant ecological function.
Can MPAs protect from climate change?
MPAs may not provide resistance against warming, but they can
provide resilience. In 2016, a strong El Ni~
no event caused the
most severe coral bleaching event in history, which killed 67% of
the coral in the northern part of the Great Barrier Reef in
Australia in just nine months (Hughes et al., 2017). However,
corals in the Line Islands affected by the strong 1997–1998 El
no recovered in fully protected reefs within a decade, whereas
they did not in unprotected islands (Sandin et al., 2008). In Baja
California, Mexico, a mass mortality event caused by climate-
driven oxygen depletion affected pink abalone populations, but
they replenished faster within marine reserves because of large
body size and high egg production of the protected adults
(Micheli et al., 2012).
Can MPAs help improve fisheries?
In the late 1990s, some fishers and fisheries scientists, mostly in
the United States, started to criticize MPAs, arguing that they can
harm fishing (Hilborn et al., 2004), and trying to place the bur-
den of proof on conservationists (Dayton, 1998). A flurry of stud-
ies followed, focused on whether MPAs produce fish “spillover”
that could help adjacent fisheries. Although MPAs were not ini-
tially conceived to help catch more fish outside their boundaries,
well-enforced marine reserves can increase adjacent fishery
catches, ensure the sustainability and increase the long-term prof-
itability of local fisheries (Halpern et al., 2009;Go~
ni et al., 2011;
Sala et al., 2013).
Some studies investigated the trade-offs between protection
and displacement of fishing effort to adjacent areas, concluding
that there is a risk these areas are depleted faster (Dinmore et al.,
2003;Hiddink et al., 2006), and that fishers displaced by protec-
tion would suffer economic losses. However, as of March 2017,
only 1.6% of the ocean is fully protected from fishing, thus the
displacement and the economic loss issues are currently insignifi-
cant at the global scale. Locally, the value of marine reserves can
also exceed the unprotected counterfactual and offset short-term
losses for fishers (Sala et al., 2016). Also, in many places marine
reserves also create other business opportunities, mostly through
ecotourism, as the growing SCUBA diver population wants to
travel to where they will see abundant marine life. In some cases,
fishers can offset potential losses and increase their incomes al-
most immediately (Sala et al., 2013,2016).
No-take marine reserves are by far the most effective type of
MPA. They restore the biomass and structure of fish assemblages,
and restore ecosystems to a more complex and resilient state.
Partially protected MPAs can have some value by restricting spe-
cific activities (e.g. banning trawling to prevent habitat destruc-
tion), but in general they are not as effective. Marine reserves are
no panacea for the ocean’s problems, but they provide outstand-
ing ecological and economic benefits within and beyond their
boundaries. In other words, they provide more than what they
were initially designed for.
Figure 1. Comparison of ecological benefits between no-take
marine reserves (MR) and partially-protected MPAs (PP). Meta-
analysis of 10 studies using log-ratios of total fish biomass (see
Supplemental online material). OA, Open Access (unprotected).
Figure 2. Recovery of fish biomass over time in adjacent marine
reserve (MR; black dots) and partially protected MPA (PP; grey
dots). Log-ratios of fish biomass relative to open access
(unprotected) areas nearby (OA). Modified from Garcia-Rubies et al.
2E. Sala and S. Giakoumi
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Supplementary data
Supplementary material is available at the ICESJMS online ver-
sion of the manuscript.
Research for this essay was supported by National Geographic
Pristine Seas, Prince Albert II of Monaco Foundation, and Total
Corporate Foundation.
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Lafferty, K. D., McClanahan, T. R., et al. 2010. Decadal trends in
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Your evidence or mine? Systematic evaluation of re-
views of marine protected area effectiveness. Fish and Fisheries,
Handling editor: Linwood Pendleton
No-take marine reserves are the most effective protected areas in the ocean 3
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... The creation of a network of Marine Protected Areas (MPAs) can provide an effective means of facilitating regeneration of marine habitats degraded by harmful fishing practices, such as the use of bottom trawls, and enabling overexploited fish populations to recover [94]. While the main objective of MPAs is to protect and regenerate marine biodiversity, they also consistently provide wider ecological and societal benefits, including in relation to increased fish biomass [95,94,96]. ...
... The creation of a network of Marine Protected Areas (MPAs) can provide an effective means of facilitating regeneration of marine habitats degraded by harmful fishing practices, such as the use of bottom trawls, and enabling overexploited fish populations to recover [94]. While the main objective of MPAs is to protect and regenerate marine biodiversity, they also consistently provide wider ecological and societal benefits, including in relation to increased fish biomass [95,94,96]. From a fisheries perspective, protecting marine environments also has the potential to be economically cost-effective as fishers may accrue increased profits associated with higher catches in surrounding areas due to larval export and spillover through movement of juveniles and adult fish and shellfish. ...
... The regeneration and protection of ecosystem complexity may have the potential to enhance resilience to climate change and contribute to mitigation of harmful climate change impacts in certain cases [103], in line with the climate change objective. MPAs may also provide a means to enable the economies of local coastal communities to adapt, through the creation of new jobs, e.g. in ecotourism [94], in accordance with the national benefits objective set out in the Act. Such diversification is preferable to reinforcing dependency on a degraded resource through supporting an unprofitable industry [104]. ...
Marine wild-capture fisheries depend on the capacity of the ocean to provide a flow of harvestable resources to sustain the industry. Paradoxically, conventional fishing often undermines these resources by degrading the environment and overexploiting fish stocks. Many UK fisheries have declined for over a century due to a biased focus on their social-economic value and lack of recognition that they are social-ecological systems and need to be managed as such. With the UK’s recent transition to an independent coastal state, the Fisheries Act (2020) and associated Joint Fisheries Statement provide an opportunity to correct this. Focusing on the ecological foundations, a more sustainable future for UK fisheries may be achieved by: (1) implementing a conservative quota setting system based on Maximum Sustainable Yield (MSY), defined as that which would occur when the biomass of a population of the target species is at 50% of that estimated at carrying capacity, to set catch limits rather than targets. The biomass of fish stocks should be allowed to regenerate to a minimum of 120% of that which will achieve MSY to provide a buffer against the uncertainty in ecological response to climate change. (2) Fishing capacity should be reduced while redistributing a greater share of the quota to sectors of the fleet that are demonstrably more sustainable; recognising that short term compensation may be required by some to mitigate the impacts of displaced activity until the benefits of stock recovery are realised. (3) Greater restrictions should be applied to ensure the most damaging fishing techniques (e.g. bottom trawling and dredging) are prohibited as appropriate in the network of marine protected areas. Protection should be enforced to promote the regeneration of degraded habitats and restoration of fish populations to help achieve the objectives as set out in the Act.
... Decades of studies in MPAs have shown that significant conservation outcomes are delivered by well-designed, fully protected areas (i.e., where no extractive activities are allowed; also known as no-take areas or marine reserves) when compared to partially protected ones (i.e., where extractive activities are allowed to a lower or higher degree) (Sciberras et al., 2015;Giakoumi et al., 2017;Sala and Giakoumi, 2018). Fully-protected areas can increase biodiversity, and boost fish biomass and abundance within their borders (Edgar et al., 2014); they have also been shown to increase fisheries in adjacent areas, while ensuring well-being and public understanding and support (Ban et al., 2019;Di Lorenzo et al., 2020;Turnbull et al., 2021). ...
... Involving and including stakeholders' opinions and concerns promotes trust and leads to better and more credible decisions, as they are perceived as fairer and result from various inputs. This rationale has been used in some cases in the zoning or rezoning of MPAs, with lessons being discussed in previous studies (Giakoumi et al., 2018;Day et al., 2019;Hogg et al., 2021). ...
... Different stakeholders' knowledge was also useful when identifying ecologically important areas while planning MPAs in Wales (Ruiz-Frau et al., 2015). Indeed, stakeholder engagement with knowledge legitimacy underlies the acceptance and respect of the zoning and protection measures (Dehens and Fanning, 2018;Giakoumi et al., 2018). ...
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Marine Protected Areas (MPAs) are a tool to safeguard marine natural systems, yet their effectiveness depends on how well they are integrated into the existing socioeconomic context. Stakeholder engagement in MPA design can contribute to increasing integration. This study focuses on the co-design of an MPA between researchers, public administration, the private sector, and non-governmental organizations. The proposed MPA is in Portugal and includes an area that is a hotspot for biodiversity and economic activities. This is the first MPA proposal in mainland Portugal co-designed using a participatory approach. This study highlights the steps of the zoning process and synthesizes the eight main lessons learned, useful for other cases, particularly for relatively small coastal MPAs with multiple socioeconomic activities. Three zoning proposals were developed and discussed within the participatory process. The proposals considered the best scientific and local knowledge available and were defined using ecological, socioeconomic, and shape-area guiding principles. In an iterative manner and following a participatory approach, compromises with stakeholders were achieved, and a final proposal, scientifically sound and socially accepted by most stakeholders, was delivered to the government. The final zoning plan will achieve ambitious conservation goals, including the largest fully protected area to be declared in mainland Portugal, while minimizing the impacts on the existing economic Frontiers in Marine Science activities and promoting its sustainability. This process resulted in valuable lessons that may be applied elsewhere and guide future MPA implementation or rezoning of existing ones. These transdisciplinary and participatory processes can be time and resource-consuming but are vital for ensuring MPA effectiveness.
... Human impacts on ocean, particularly overfishing and pollution, are causing the loss of marine biodiversity [17]. Thus, marine-protected areas (MPAs) have been established to conserve the biodiversity and ecosystem of oceans [18]. The MPAs have been confirmed as an effective area-based tool to protect marine biodiversity [19]. ...
... MPAs have been demonstrated to be one of the most effective tools for restoring marine biodiversity and ecosystem services [18]. The requirement to increase the coverage of MPAs has been already recognised in CBD post-2020 global biodiversity framework. ...
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Marine biodiversity plays important roles in ocean ecosystem services and has substantial economic value. Species diversity (SR), genetic diversity (GD) and phylogenetic diversity (PD), which reflect the number, evolutionary potential and evolutionary history of species in ecosystem functioning, are three important dimensions of biodiversity. Marine protected areas (MPAs) have been demonstrated as an effective area-based tool for protecting marine biodiversity, but only 2.8% of the ocean has been fully protected. It is urgent to identify global conservation priority areas and percentage of the ocean across multiple dimensions of biodiversity based on Post-2020 Global Biodiversity Framework. Here, we investigate the spatial distribution of marine genetic and phylogenetic diversity using 80 075 mitochondrial DNA barcode sequences from 4 316 species and a newly constructed phylogenetic tree of 8 166 species. We identify that the Central Indo-Pacific Ocean, Central Pacific Ocean and Western Indian Ocean harbour high levels of biodiversity across three dimensions of biodiversity, which could be designated as conservation priority areas. We also find that strategically protecting approximately 22% of the ocean would allow us to reach the target of conserving approximately 95% of currently known taxonomic, genetic and phylogenetic diversity. Our study provides insights into the spatial distribution pattern of multiple marine diversities and the findings would help to design comprehensive conservation schemes for global marine biodiversity.
... Other reefs can host a very high fish biomass but with low biomass turnover. In this case, if these reefs are not already under some kind of protection, preserving the ecological states, processes and contributions associated with high fish biomass by placing a no-take or no-entry MPA may be appropriate when socially feasible or acceptable 24,32 . Using 1,979 tropical reef sites from a global database on fish community composition and size structure, we calculated fish biomass, biomass production and biomass turnover ( Supplementary Fig. 1). ...
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Tropical reefs and the fish relying on them are under increasing pressure. Shallow-reef fish provide important ecological information in addition to sustaining fisheries, tourism and more. Although empirical metrics of fish biomass are widely used in fisheries management, metrics of biomass production—how much new biomass is produced over time—are rarely estimated even though such production informs potential fisheries yields. Here we estimate fish standing biomass (B), biomass production (P, the rate of biomass accumulation) and biomass turnover (P/B ratio, the rate of biomass replacement) for 1,979 tropical reef sites spanning 39 tropical countries. On the basis of fish standing biomass and biomass turnover, we propose a conceptual framework that splits reefs into three classes to visualize ecological and socio-economic risk and help guide spatial management interventions (for example, marine protected areas) to optimize returns on conservation efforts. At large scales, high turnover was associated with high human pressure and low primary productivity, whereas high biomass was associated with low human pressure and high primary productivity. Going beyond standing fish biomass to consider dynamic ecological processes can better guide regional coral reef conservation and sustainable fisheries management.
... Marine protected areas (MPAs) are a well-recognized, effective conservation tool used to address biodiversity loss and the resulting impacts on social, economic, and cultural well-being (Millennium Ecosystem Assessment 2005;Dudley 2008;Sala and Giakoumi 2018). In the past two decades, international biodiversity and conservation initiatives (e.g., Aichi Target 11) have facilitated the accelerated rate of MPA implementation globally (Maestro et al. 2019). ...
This research examines the potential challenges and opportunities for Mi’kmaq, the Indigenous peoples who have inhabited modern-day Nova Scotia and other areas of Eastern Canada for millennia, to play a greater role in marine protected area (MPA) governance in Canada. Given Canada’s marine conservation objectives of 30% by 2030, there is a growing need for decisions affecting the establishment of MPAs to respect Indigenous rights, values, and knowledge. Using the Eastern Shore Islands (ESI) in Nova Scotia, Canada, an area of interest for MPA establishment, as a case study, we conducted 17 semi-structured interviews with both Mi’kmaq and non-Mi’kmaq participants involved in the ESI consultation processes. We used content analysis to identify key themes that respondents perceived to be affecting Mi’kmaq involvement in the federal MPA governance processes. Barriers to overcome included those deemed to be systemic within the current decision-making processes; limited understanding of Mi’kmaq culture, governance, and rights; limited clarity of Mi’kmaq rights, particularly those resulting in fisheries conflicts; and limited capacity. Opportunities highlighted the importance of meaningful consultation and understanding of Indigenous worldviews as well as the need for alternative approaches to state-led/top-down governance to improve Mi’kmaq participation in MPA governance in Atlantic Canada.
... A review of the outcomes of nature-based interventions for climate change adaptation by Chausson et al. (2020) recorded information on the overall ecological outcomes of interventions, but did not record individual ecosystem health metrics such as species richness. There are also numerous reviews of the ecosystem health outcomes of specific types of conservation interventions, such as for terrestrial protected areas (e.g., Gray et al., 2016;Geldmann et al., 2018), marine protected areas (e.g., Sala and Giakoumi, 2018), and natural forest regeneration (e.g., Uebel et al., 2017), as well as the outcomes of plantation forestry (e.g., Bremer et al., 2010). ...
Full-text available
Nature-based solutions (NbS) are increasingly recognised for their potential to address both the climate and biodiversity crises. Both these outcomes rely on the capacity of NbS to support and enhance the health of an ecosystem: its biodiversity, the condition of its abiotic and biotic elements, and its capacity to continue to function despite environmental change. However, while understanding of ecosystem health outcomes of NbS for climate change mitigation has developed in recent years, the outcomes of those implemented for adaptation remain poorly understood. To address this, we systematically reviewed the outcomes of 109 nature-based interventions for climate change adaptation using 33 indicators of ecosystem health across eight broad categories (e.g., diversity, biomass, ecosystem composition). We showed that 88% of interventions with reported positive outcomes for climate change adaptation also reported benefits for ecosystem health. We also showed that interventions were associated with a 67% average increase in species richness. All eight studies that reported benefits for both climate change mitigation and adaptation also supported ecosystem health, leading to a “triple win.” However, there were also trade-offs, mainly for forest management and creation of novel ecosystems such as monoculture plantations of non-native species. Our review highlights two key limitations in our understanding of the outcomes of NbS for ecosystem health. First, a limited selection of metrics are used and these rarely include key aspects such as functional diversity and habitat connectivity. Second, taxonomic coverage is limited: 50% of interventions only had evidence for effects on plants, and 57% of outcomes did not distinguish between native and non-native species. We make suggestions of how to improve assessments of the ecosystem health outcomes of NbS, as well as policy recommendations to enable the upscaling of NbS that support flourishing and resilient ecosystems, and are effective in addressing both climate and biodiversity goals.
... Despite the significant expansion of protected areas over the past several decades, accumulating evidence indicates that the intended goal of halting and reversing the decline of wild species and ecosystems is not being met (Díaz et al., 2019;Geldmann et al., 2019). Furthermore, governance and management efficacy for conserving biodiversity within protected areas has been questioned and criticized for receiving inadequate attention (Sala and Giakoumi, 2018;Woodcock et al., 2017;Woodley et al., 2019). Such realizations have spurred calls for increased focus on the effectiveness of protected areas (Hockings et al., 2019;Visconti et al., 2019). ...
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Other Effective Area-based Conservation Measures (OECMs) were introduced in the language of the United Nations Convention on Biological Diversity (CBD) 2011–2020 Strategic Plan for Biodiversity as a mechanism to formally recognize the contributions that areas beyond traditional protected areas can make to the effective, long-term, in-situ conservation of biodiversity. Since the international conservation community agreed to a definition of OECMs in 2018, various Parties to the CBD have begun designating these areas and they are now being reported in global and national protected and conserved area databases. Using examples from Canada, this perspective details how the designation of some OECMs is circumventing the use of established and well-known decision support tools that work to uphold conservation standards, and why these designations may result in negligible gains for biodiversity. The perspective also details how labeling OECMs as “marine refuges” and “conserved areas” is misleading and can misinform the public on conservation success. To avoid the loss of biodiversity in ‘paper parks’ and eroding public trust in the institutions charged with effectively conserving biodiversity, the paper concludes by underscoring the need for new tools to evaluate the effectiveness of OECMs and new measures to hold countries accountable to protected and conserved area targets in the CBD so that their original intent is not further compromised in the post-2020 era of conservation.
Marine Protected Areas (MPAs) are advocated as tools to support sustainable fisheries and biodiversity by excluding the most destructive fishing practices. Some MPAs protect the whole-site of habitat mosaics from bottom-towed fishing but most only restrict damaging activities from specific evidenced conservation features. Social and economic factors influence the success of an MPA but the impact of spatial management changes to local fisheries is rarely captured in post MPA designation monitoring. In Jersey, Channel Islands, two offshore MPAs were designated in 2017 that are managed following the whole-site approach. This study provides an insight into the overall economic importance of key fishery species (whelk (Buccinum undatum), brown crab (Cancer pagurus), scallop (Pecten maximus), lobster (Homarus gammarus), and spider crab (Maja brachydactyla) to local fishing fleets and the impact of the MPAs on local, small-scale fishers in Jersey. Total landings (kg and £) in Jersey pre and post MPA designation were calculated from logbook and primary sales data and a structured interview was developed and tested as a research tool to document the impact (positive and negative) of the MPA designation on local fishers. Specific questions were designed to elicit both quantitative and qualitative data relating to the participants (n = 21) fishing activity; support for the MPAs; income and job satisfaction; subjective well-being and current sales strategies. The results demonstrate that one mobile gear vessel respondent was displaced from traditional fishing grounds as a result of the MPA designation. Fishers also reported an increase in static fishing inside the MPAs, post designation. Generally, there are high levels of support for the MPA from static fleet respondents. In the first year since designation there have been no reported changes to catch (kg, £). Mobile gear fishers reported a lower subjective wellbeing and satisfaction with their job and income than static gear fishers, despite greater profits. The major concern reported by the mobile fleet that contributed to their stress levels, was not attributed to the MPA designations but related to conflict with French static net fisheries operating outside of the MPAs. Ongoing support for Jersey’s fishers and securing a sustainable and fulfilling livelihood will require further spatial management of fisheries outside of the MPAs with a possibility of setting gear or effort limits on static fishereis within the MPAs.
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Marine protected areas (MPAs) are designated to protect marine ecosystems and, among other things, to monitor climate variability, which in turn affects aquatic species. The aim of this study is to examine the contribution of remotely sensed data as an indication of Holothuria abundance, by investigating the spatiotemporal variability of physicochemical parameters. The study area is in the National Marine Park of Alonissos Northern Sporades, which is included in the NATURA 2000 network. Firstly, the abundance of Holothuria species was measured by scuba diving. At the same time, depth profiles of five physicochemical parameters (temperature, salinity, pH, dissolved oxygen and Chl-a) were recorded by CTD (conductivity, temperature, depth), a primary instrument used to determine the essential physical and chemicals properties of seawater column profiles in the coastal zone. The physicochemical variables examined are the most common environmental parameters with the highest impact on growth, reproduction, productivity and survival rate of sea cucumber species, affecting the availability of food sources. Analysis of this data allows us to identify parameters which are essential for their existence. The analysis showed that only temperature and Chlorophyll-a (Chl-a) could be useful for identifying the abundance. These two parameters are readily available from satellite data. Additionally, particulate organic carbon (POC) is essential for Holothuria’s existence. Consequently, a time series of satellite data products from Terra/MODIS sensor were utilized from 2000 to 2020 for sea surface temperature (SST), Chl-a and POC. The monthly temporal trend shows that the abundance could be justified in areas where the Holothuria presence has been established. Monthly spatiotemporal analysis shows that SST, Chl-a and POC availability, could be an indication of the differences in abundance recorded.
Effectiveness of restocking programs in Marine Fully Protected Areas' (FPAs) can be highly affected by the movement behavior of the species to protect. We analyzed the data of 744 Palinurus elephas specimens tagged, relocated inside 12 FPAs, established in the seas surrounding Sardinia (central-western Mediterranean), and then recaptured. The overall aims were to characterize the individuals' movements after the relocation and to discuss strengths and weaknesses of the current FPAs' design. Almost 80% of tagged individuals travelled progressively increasing distances, as a function of the release distance, up to a maximum value of 11,500 m. Then, for larger release distances, individuals' mobility appeared reduced and more chaotic. A similar trend was found analyzing the distances travelled with respect to the FPAs with the highest number of recaptured individuals and to the size. These results allow to establish a threshold limit of the release distance, to take into account when designing FPAs, as a useful tool to keep a portion of the individuals into FPAs’ borders, in order to both preserve the species and guarantee a spillover of individuals in the commercial areas.
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Only 2.1% of the ocean is in actively managed marine protected areas (MPAs). Achieving the United Nations' target of 10% of the ocean protected by 2020 will require an aggressively implemented mix of large MPAs in remote areas, and small MPAs in inhabited coastal areas. Replication of small no-take MPAs (marine reserves) in coastal areas at the global scale is more likely to occur if reserves are designed as investment opportunities – ‘fish banks’ that produce new profits based on ecosystem services such as tourism and fish production. Here a pro forma business plan for a marine reserve using private investment and local management is presented. Total annual profit before the reserve was €254,000 (from fishing only); in year 8 after creation of the reserve, profit (fishing+tourism) was €3.3 million. Given the right conditions, the net present value of the reserve can be between 4 and 12 times greater than the no-reserve counterfactual. In our model, (1) the tourism sector covers the costs of creation and operation of the reserve as an investment in a profitable business; and (2) fishers become shareholders and receive income from tourist access fees; their profits increase as soon as one year after the creation of the reserve. A series of financing mechanisms to create and manage fish banks is also proposed. If designed properly, fish banks can help restore marine biodiversity and ecosystem services, and can create jobs, help fishers, and bring in significantly greater economic profits than the absence of protection.
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Mature science reveals opportunities for policy progress.
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Human-induced environmental disturbance – through fishery activities, coastal development, tourism and pollution – is a major challenge to the restoration and conservation of marine biodiversity. Synthesizing the latest research into marine biodiversity conservation and fisheries management, this book provides regional and global perspectives on the role of Marine Protected Areas (MPAs) in confronting this challenge. The approach is multidisciplinary, covering all the fields involved in designating and assessing MPAs: ecology, fisheries science, statistics, economics, sociology and genetics. The book is structured around key topics, including threats to marine ecosystems and resources, the effects and effectiveness of MPAs and the scaling-up of MPA systems. Both theoretical and empirical approaches are considered. Recognizing the diversity of MPA sciences, the book also includes one part designed specifically as a practical guide to implementing scientific assessment studies of MPAs and monitoring programs.
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Based on 19 y of visual census data from the Medes Islands MPA (NW Mediterranean), this study analyzes the carrying capacity (K) and population recovery time of six species of fish strongly affected by harvesting pressure along the Mediterranean coast. Three of these species (Epinephelus marginatus, Diplodus cervinus and Dicentrachus labrax) have practically reached carrying capacity in the Medes Islands MPA, while others are still approaching population stabilization (Sciaena umbra) or are still increasing in biomass (Dentex dentex). The one exception to these trends is S. aurata, which tended to decrease inside the MPA, probably due to fishing just outside its borders. These results confirm that fish populations may require decadal time scales to recover from exploitation, both in terms of total abundance (21 to 29 y to exceed 95% K) as well as total biomass (25 to 35 y), and that rates of recovery differ between species (13 to 31 y). The recovery and saturation observed within the no-take zone contrasts with results obtained in the partially protected buffer area and the peripheral area open for fishing, which show much lower biomass values. In general, the spillover from the MPA is very moderate, and its effects extend only to the partially protected area.
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Between 1978 and 1996 benthic communities in the Leigh Marine Reserve shifted from being dominated by sea urchins to being dominated by macroalgae. This was a result of a trophic cascade thought to be an indirect effect of increased predator abundance. We assessed further changes in communities from 1996 to 2000, differences in benthic communities between reserve and adjacent unprotected sites, and the stability of these patterns from 1999 to 2001. Since 1996, densities of sea urchins Evechinus chloroticus have continued to decline in shallow areas of the reserve (< 8 m), and all sites classified as urchin barrens in 1978. are now dominated by large brown algae. Comparisons between reserve and non-reserve sites revealed differences consistent with a trophic cascade at reserve sites. The greatest differences in algal communities between reserve and non-reserve sites occurred at depths where E. chloroticus was most abundant (4 to 6 m). Reserve sites had lower urchin densities and reduced extent of urchin barrens habitat with higher biomass of the 2 dominant algal species (Ecklonia radiata and Caipophyllum maschalocarpum). At reserve sites densities of exposed E. chloroticus (openly grazing the substratum) declined so that urchin barrens were completely absent by 2001. Lower density of the limpet Cellana stellifera and higher densities of the turbinid gastropod Cookia sulcata at reserve sites are thought to be responses to changes in habitat structure, representing additional indirect effects of increased predators. The overall difference in community types between reserve and non-reserve sites remained stab le between 1999 and 2001. Localised urchin mortality events due to an unknown agent were recorded at some sites adjacent to the marine reserve. Only at 1 of these sites did exposed urchins decline below the critical density of 1 m(-2), which resulted in the total replacement of urchin barrens with macroalgae-dominated habitats. At other sites urchin barrens have remained stable. Declines in the limpet C. stellifera occurred across all sites between 1999 and 2001 and may be indirectly associated with urchin declines. Long-term changes in benthic communities in the Leigh reserve and the stability of differences between reserve and non-reserve sites over time are consistent with gradual declines in urchin densities due to increased predation on urchins, thus providing further evidence for a trophic cascade in this system. The rapid declines in urchin numbers at some unprotected sites, however, demonstrate how short-term disturbances, such as disease, may result in shifts in community types over much shorter time frames.
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Marine reserves are an effective tool for protecting biodiversity locally, with potential economic benefits including enhancement of local fisheries, increased tourism, and maintenance of ecosystem services. However, fishing communities often fear short-term income losses associated with closures, and thus may oppose marine reserves. Here we review empirical data and develop bioeconomic models to show that the value of marine reserves (enhanced adjacent fishing + tourism) may often exceed the pre-reserve value, and that economic benefits can offset the costs in as little as five years. These results suggest the need for a new business model for creating and managing reserves, which could pay for themselves and turn a profit for stakeholder groups. Our model could be expanded to include ecosystem services and other benefits, and it provides a general framework to estimate costs and benefits of reserves and to develop such business models.
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In his research commentary, Dayton argues that decisions in fisheries management should follow the model of the U.S. Nuclear Regulatory Commission or the Food and Drug Administration in which the commercial enterprise must prove that their activity or product does no harm before it can be approved. At present, fishing activities cannot be curtailed until it can be proven that they are already damaging existing ecosystems (see report and news story in this issue).
During 2015-2016, record temperatures triggered a pan-tropical episode of coral bleaching, the third global-scale event since mass bleaching was first documented in the 1980s. Here we examine how and why the severity of recurrent major bleaching events has varied at multiple scales, using aerial and underwater surveys of Australian reefs combined with satellite-derived sea surface temperatures. The distinctive geographic footprints of recurrent bleaching on the Great Barrier Reef in 1998, 2002 and 2016 were determined by the spatial pattern of sea temperatures in each year. Water quality and fishing pressure had minimal effect on the unprecedented bleaching in 2016, suggesting that local protection of reefs affords little or no resistance to extreme heat. Similarly, past exposure to bleaching in 1998 and 2002 did not lessen the severity of bleaching in 2016. Consequently, immediate global action to curb future warming is essential to secure a future for coral reefs.
Marine protected areas (MPAs) are a key strategy for mitigating the impacts of fisheries, but their designation can be controversial, and there is uncertainty surrounding when and where MPAs are most effective. Evidence synthesis that collates primary research on MPA effectiveness can provide a crucial bridge between research, policy and practice. However, reviews vary in scope and rigour, meaning decision-makers face the challenge of identifying appropriate reviews. Documenting differences amongst reviews can therefore support nonspecialists in locating the most relevant and rigorous reviews and can also assist researchers in targeting evidence gaps. We addressed these priorities by systematically searching for reviews examining effectiveness of MPAs for biodiversity, critically appraising methods used and categorizing review scope. The 27 reviews assessed overlapped in scope (suggesting some redundancy) and differed substantially in reliability. Key strengths related to the effects of MPAs on fish abundance and the influence of MPA size and age on effectiveness. However, several gaps were noted, with some questions not addressed and others lacking highly reliable syntheses – importantly, the latter may create the perception that particular questions have been adequately addressed, potentially deterring new syntheses. Our findings indicate key aspects of review conduct that could be improved (e.g. documenting critical appraisal of primary research, evaluating potential publication bias) and can facilitate evidence-based policy by guiding nonspecialists to the most reliable and relevant reviews. Lastly, we suggest that future reviews with broader taxonomic coverage and considering the influence of a wider range of MPA characteristics on effectiveness would be beneficial.
Seasonal area closures of fisheries are primarily used to reduce fishing mortality on target species. In the absence of effort controls, fishing vessels displaced from a closed area will impact fish populations and the environment elsewhere. Based on the observed response of the North Sea beam trawl fleet to the closure of the ''cod box'' and an existing size-based model of the impacts of beam trawling, we predict the effects of seasonal area closures on benthic communities in the central North Sea. We suggest that repeated seasonal area closures would lead to a slightly more homogeneous distribution of annual trawling activity, although the distribution would remain patchy rather than random. The increased homogeneity, coupled with the displacement of trawling activity to previously unfished areas, is predicted to have slightly greater cumulative impacts on total benthic invertebrate production and lead to localized reductions in benthic biomass for several years. To en- sure the effective integration of fisheries and environmental management, the wider consequences of fishery management actions should be considered a priori. Thus, when seasonal closures increase the homogeneity of overall disturbance or lead to the re- distribution of trawling activity to environmentally sensitive or previously unfished areas, then effort reductions or permanent area closures should be considered as a manage- ment option. The latter would lead to a single but permanent redistribution of fishing disturbance, with lower cumulative impacts on benthic communities in the long run. 2003 International Council for the Exploration of the Sea. Published by Elsevier Science Ltd. All rights