• Energy Research

Marine protected areas (MPAs) are widely used for ocean conservation, yet the relative impacts of various types of MPAs are poorly understood. We estimated impacts on fish biomass from no-take and multiple-use (fished) MPAs, employing a rigorous matched counterfactual design with a global dataset of >14,000 surveys in and around 216 MPAs. Both no-take and multiple-use MPAs generated positive conservation outcomes relative to no protection (58.2% and 12.6% fish biomass increases, respectively), with smaller estimated differences between the two MPA types when controlling for additional confounding factors (8.3% increase). Relative performance depended on context and management: no-take MPAs performed better in areas of high human pressure but similar to multiple-use in remote locations. Multiple-use MPA performance was low in high-pressure areas but improved significantly with better management, producing similar outcomes to no-take MPAs when adequately staffed and appropriate use regulations were applied. For priority conservation areas where no-take restrictions are not possible or ethical, our findings show that a portfolio of well-designed and well-managed multiple-use MPAs represents a viable and potentially equitable pathway to advance local and global conservation.

As the human population and demand for food grow1, the ocean will be called on to provide increasing amounts of seafood. Although fisheries reforms and advances in offshore aquaculture (hereafter 'mariculture') could increase production2, the true future of seafood depends on human responses to climate change3. Here we investigated whether coordinated reforms in fisheries and mariculture could increase seafood production per capita under climate change. We find that climate-adaptive fisheries reforms will be necessary but insufficient to maintain global seafood production per capita, even with aggressive reductions in greenhouse-gas emissions. However, the potential for sustainable mariculture to increase seafood per capita is vast and could increase seafood production per capita under all but the most severe emissions scenario. These increases are contingent on fisheries reforms, continued advances in feed technology and the establishment of effective mariculture governance and best practices. Furthermore, dramatically curbing emissions is essential for reducing inequities, increasing reform efficacy and mitigating risks unaccounted for in our analysis. Although climate change will challenge the ocean's ability to meet growing food demands, the ocean could produce more food than it does currently through swift and ambitious action to reduce emissions, reform capture fisheries and expand sustainable mariculture operations.

AbstractMarine protected areas (MPAs) have gained attention as a conservation tool for enhancing ecosystem resilience to climate change. However, empirical evidence explicitly linking MPAs to enhanced ecological resilience is limited and mixed. To better understand whether MPAs can buffer climate impacts, we tested the resistance and recovery of marine communities to the 2014–2016 Northeast Pacific heatwave in the largest scientifically designed MPA network in the world off the coast of California, United States. The network consists of 124 MPAs (48 no‐take state marine reserves, and 76 partial‐take or special regulation conservation areas) implemented at different times, with full implementation completed in 2012. We compared fish, benthic invertebrate, and macroalgal community structure inside and outside of 13 no‐take MPAs across rocky intertidal, kelp forest, shallow reef, and deep reef nearshore habitats in California's Central Coast region from 2007 to 2020. We also explored whether MPA features, including age, size, depth, proportion rock, historic fishing pressure, habitat diversity and richness, connectivity, and fish biomass response ratios (proxy for ecological performance), conferred climate resilience for kelp forest and rocky intertidal habitats spanning 28 MPAs across the full network. Ecological communities dramatically shifted due to the marine heatwave across all four nearshore habitats, and MPAs did not facilitate habitat‐wide resistance or recovery. Only in protected rocky intertidal habitats did community structure significantly resist marine heatwave impacts. Community shifts were associated with a pronounced decline in the relative proportion of cold water species and an increase in warm water species. MPA features did not explain resistance or recovery to the marine heatwave. Collectively, our findings suggest that MPAs have limited ability to mitigate the impacts of marine heatwaves on community structure. Given that mechanisms of resilience to climate perturbations are complex, there is a clear need to expand assessments of ecosystem‐wide consequences resulting from acute climate‐driven perturbations, and the potential role of regulatory protection in mitigating community structure changes.

Accounting for a warming ocean Fisheries provide food and support livelihoods across the world. They are also under extreme pressure, with many stocks overfished and poorly managed. Climate change will add to the burden fish stocks bear, but such impacts remain largely unknown. Free et al. used temperature-specific models and hindcasting across fish stocks to determine the degree to which warming has, and will, affect fish species (see the Perspective by Plagányi). They found that an overall reduction in yield has occurred over the past 80 years. Furthermore, although some species are predicted to respond positively to warming waters, the majority will experience a negative impact on growth. As our world warms, responsible and active management of fisheries harvests will become even more important. Science , this issue p. 979 ; see also p. 930

Abstract Coral reef fisheries are a vital source of nutrients for thousands of nutritionally vulnerable coastal communities around the world. Here, we evaluated the potential effects of expanding sustainable-use marine protected areas (MPAs) to improve the nutrition of coastal communities. Using information from underwater visual surveys from 2,518 sites located in 53 countries, we developed a Bayesian hierarchical model to estimate the average effect of existing sustainable-use MPAs reef fish biomass and explored how that may alter fish catch, and the nutrients supplied to local communities. We then estimated the potential nutritional benefits of expanding sustainable-use MPAs to all non-MPA coral reefs globally. We found that existing sustainable use MPAs have on average 15% more biomass than open access reefs. Translating this into catch, we estimated that expanding sustainable-use MPAs could increase catch potential by 0-20%, which could prevent 0.53-1.95 million cases of inadequate micronutrient intake globally, a fraction of the people who would continue to be sustained by this foundation of coastal food systems. Our study estimates the potential nutritional benefits of expanding sustainable-use MPAs and pinpoints locations with the greatest potential to reduce inadequate micronutrient intake levels, critical knowledge given the strong international movement to cover 30% of our oceans with MPAs by 2030.