Predicting impact to assess the efficacy of community-based marine reserve design

During the planning phase the efficacy of different strategies to manage marine resources should ultimately be assessed by their potential impact, or ability to make a difference to ecological and social outcomes. While community-based and systematic approaches to establishing marine protected areas have their strengths and weaknesses, comparisons of their effectiveness often fail to explicitly address potential impact. Here, we predict conservation impact to compare recently implemented community-based marine reserves in Tonga to a systematic configuration specifically aimed at maximizing impact. Boosted regression tree outputs indicated that fishing pressure accounted for ∼24% of variation in target species biomass. We estimate that the community-based approach provides 84% of the recovery potential of the configuration with the greatest potential impact. This high potential impact results from community-based reserves being located close to villages, where fishing pressure is greatest. These results provide strong support for community-based marine management, with short-term benefits likely to accrue even where there is little scope for systematic reserve design

Spatial subsidies drive sweet spots of tropical marine biomass production

Spatial subsidies increase local productivity and boost consumer abundance beyond the limits imposed by local resources. In marine ecosystems, deeper water and open ocean subsidies promote animal aggregations and enhance biomass that is critical for human harvesting. However, the scale of this phenomenon in tropical marine systems remains unknown. Here, we integrate a detailed assessment of biomass production in 3 key locations, spanning a major biodiversity and abundance gradient, with an ocean-scale dataset of fish counts to predict the extent and magnitude of plankton subsidies to fishes on coral reefs. We show that planktivorous fish-mediated spatial subsidies are widespread across the Indian and Pacific oceans and drive local spikes in biomass production that can lead to extreme productivity, up to 30 kg ha−1 day−1. Plankton subsidies form the basis of productivity “sweet spots” where planktivores provide more than 50% of the total fish production, more than all other trophic groups combined. These sweet spots operate at regional, site, and smaller local scales. By harvesting oceanic productivity, planktivores bypass spatial constraints imposed by local primary productivity, creating “oases” of tropical fish biomass that are accessible to humans

Incentivizing co-management for impact: mechanisms driving the successful national expansion of Tonga's Special Management Area program

The expansion of coastal marine protected areas can suffer from two key drawbacks: (a) the difficulty of incentivizing local communities to manage areas for conservation when their livelihoods also depend on resource use; and (b) that many protected areas get situated residually, or in locations with limited value for either biodiversity conservation or livelihoods. Here, we discuss and analyze key characteristics of Tonga's Special Management Area (SMA) program, including both the mechanisms that have motivated its successful national expansion and its ability to configure no-take reserves in areas that are considered to have high value to resource users. Granting communities exclusive access zones in exchange for implementing no-take reserves has encouraged conservation actions while fostering long-term relationships with resources. Ensuring no-take reserves occurred within the boundaries of exclusive access zones enabled communities to protect areas of greater extractive values than they would have otherwise. We conclude that the success of this program offers a way forward for achieving targets in the global expansion marine protected areas

Hidden benefits and risks of partial protection for coral reef fisheries

Partially protected areas are now the dominant global form of spatial management aimed at preserving ecosystem integrity and managing human use. However, most evaluations of their efficacy use only a narrow set of conservation indicators that reflect a fraction of ways in which protection can succeed or fail. In this paper, we examine three case studies of partially protected coral reef fishery systems to evaluate benefits and risks of their use as a management tool. We use data from community-based management arrangements in three Pacific Island countries to demonstrate three vignettes of how partial protection can boost fisheries production, enhance the ease with which fishers catch their prey, and alter the composition of fisheries yields. These changes in fisheries productivity, catchability, and vulnerability under partial protection carry substantial benefits for fishers. However, they also carry significant risks for ecosystems and fisheries livelihoods unless adaptively managed so as to confer the short to medium term benefits in resource performance without risking longer term sustainability

Why does conservation minimize opportunity costs?

Effective management of depleted natural resources can be achieved only through changes in human actions. Opportunity costs represent the forgone benefits that would have flowed in the absence of conservation interventions. To the extent that opportunity costs reflect lost opportunities for extractive uses (e.g., fishing or logging), and to the extent that those extractive uses present threats to nature, opportunity costs therefore reflect the positive differences for natural values that can be made through conservation management. Thus, logic dictates that, if conservationists make choices to minimize opportunity costs, they are also necessarily limiting their impact. Unfortunately, empirical evidence from many conservation contexts implies that conservationists indeed make choices consistent with an aim to minimize opportunitycosts, and hence impact. A better understanding of the relationship between opportunity costs and conservation impact will make the language used to communicate conservation progress, targets, and planning more honest and accountable and more explicitly focused on the differences our actions make.</p

Tonga Reef survey data 2016-2018, link to xlsx files

This data represents coral reef ecological surveys conducted in the Kingdom of Tonga from 2016-2018. 375 sites were surveyed across the Tongatapu, Ha'apai and Vava'u island groups by Patrick Smallhorn-West, Dr. Daniela Ceccarelli and Karen Stone. Data includes reef fish belt transects and benthic photoquadrats or point intercept data. In addition, the values of a range of socio-environmental predictor variables are also included in this data set. Two files are uploaded: Tonga Reef Surveys Raw Data 2016-2018 contains the raw reef fish data. Tonga Reef Surveys Transect Data 2016-2018 contains the transect level values. All surveys were conducted on SCUBA. Metadata on depth, location, transect length, width etc. are included in the data files. Socio-environmental spatial data is available at https://doi.pangaea.de/10.1594/PANGAEA.90480

Ecological and socioeconomic impacts of marine protected areas in the South Pacific: assessing the evidence base

Marine protected areas (MPAs) in the South Pacific have a unique history that calls for a regional-scale synthesis of MPA impacts and the factors related to positive ecological and socioeconomic change. However, recommendations of best approaches to MPA implementation can be made only when evaluation techniques are sound. Impact evaluation involves quantifying the effects of an intervention over and above the counterfactual of no intervention or a different intervention. Determining the true impact of an MPA can be challenging because additional factors beyond the presence of an MPA can confound the observed results (e.g. differences in ecological or socioeconomic conditions between MPA and control sites). While impact evaluation techniques employing counterfactual thinking have been well developed in other fields, they have been embraced only slowly in the MPA evaluation literature. We conducted a structured literature search and synthesis of MPA evaluation studies from the South Pacific to determine: (i) the overall ecological and socioeconomic impacts of MPAs in the region, (ii) what factors were associated with positive, neutral, or negative impacts, and (iii) to what extent the MPA evaluation literature from the region has incorporated counterfactual thinking and robust impact evaluation techniques. Based on 52 identified studies, 42% of measured ecological impacts were positive. While 72% of socioeconomic impacts were positive, these were from only eight studies. The proportion of positive impacts was comparable between community-based and centrally governed MPAs, suggesting that both governance approaches are viable options in the region. No-take MPAs had a greater number of positive ecological impacts than periodic closures and there was little evidence of any long-term ecological recovery within periodic closures following harvesting. Importantly, more than half of the studies examined (59%) did not provide any clear consideration of factors beyond the presence of the MPA that might have confounded their results. We conclude that counterfactual thinking has yet to be fully embraced in impact evaluation studies in the region and recommend pathways by which progress can be made