INTRODUCTION

More than three billion people depend on seafood for almost 20% of their protein and essential nutrients, but two-thirds of fish stocks are in poor biological condition, one-third are overfished, and catch from wild capture fisheries has been steadily declining since 1996 (Costello et al. 2016aCostello C., Ovando D., Clavelle T., et al. 2016a. Global fishery prospects under contrasting management regimes. Proc. Nat. Acad. Sci. 113: 5125-5129. https://doi.org/10.1073/pnas.1520420113 , Pauly and Zeller 2016Pauly D., Zeller D. 2016. Catch reconstructions reveal that global marine fisheries catches are higher than reported and declining. Nature Comm. 7: 10244. https://doi.org/10.1038/ncomms10244 , FAO 2019FAO. 2019. FAO yearbook. Fishery and Aquaculture Statistics 2017. Rome. Accessed 18/06/20. http://www.fao.org/3/ca5495t/CA5495T.pdf ). With a growing population and increasing anthropogenic pressure on the oceans, future food security for much of the human population is at risk (Worm 2016Worm B. 2016. Averting a global fisheries disaster. Proc. Nat. Acad. Sci. 113 (18): 4895-4897. https://doi.org/10.1073/pnas.1604008113 , Roberts et al. 2017Roberts C.M., O’Leary B.C., McCauley D.J. et al. 2017. Marine reserves can mitigate and promote adaptation to climate change. Proc. Nat. Acad. Sci. 114: 6167-6175. https://doi.org/10.1073/pnas.1701262114 ). To avert negative effects on food security, changes in fisheries management practices are needed. Optimizing commercial fisheries for long-term profits, rather than annual maximum sustainable yield, could triple economic benefits from fishing and stabilize 97% of fish stocks by 2050 (Costello et al. 2016aCostello C., Ovando D., Clavelle T., et al. 2016a. Global fishery prospects under contrasting management regimes. Proc. Nat. Acad. Sci. 113: 5125-5129. https://doi.org/10.1073/pnas.1520420113 , Worm 2016Worm B. 2016. Averting a global fisheries disaster. Proc. Nat. Acad. Sci. 113 (18): 4895-4897. https://doi.org/10.1073/pnas.1604008113 ).

In addition to food insecurity, we are in the midst of a biodiversity crisis (McCauley et al. 2015McCauley D.J., Pinsky M.L., Palumbi S.R. et al. 2015. Marine defaunation: animal loss in the global ocean. Science 347 (6219): 1255641. https://doi.org/10.1126/science.1255641 ). The overexploitation of marine wildlife has led to trophic cascades that alter entire ecosystems, and species that were once common are now threatened with extinction (McCauley et al. 2015McCauley D.J., Pinsky M.L., Palumbi S.R. et al. 2015. Marine defaunation: animal loss in the global ocean. Science 347 (6219): 1255641. https://doi.org/10.1126/science.1255641 ). This overexploitation of biodiversity destabilizes ecological and economic ecosystem services, hindering sustainable food provisioning, carbon sequestration and fisheries economic benefits (Costello and Baker 2011Costello M.J., Baker C.S. 2011. Who eats sea meat? Expanding human consumption of marine mammals. Biol. Conserv. 12: 2745-2746. https://doi.org/10.1016/j.biocon.2011.10.015 , McCauley et al. 2015McCauley D.J., Pinsky M.L., Palumbi S.R. et al. 2015. Marine defaunation: animal loss in the global ocean. Science 347 (6219): 1255641. https://doi.org/10.1126/science.1255641 , Epstein et al. 2022Epstein G., Roberts C.M. 2022. Identifying priority areas to manage mobile bottom fishing on seabed carbon in the UK. PLoS Climate 1: e0000059. https://doi.org/10.1371/journal.pclm.0000059 ). In light of these challenges, marine protected areas (MPAs) have been used to protect and restore ecosystems and their associated habitats, populations and services (Selig and Bruno 2010Selig E.R., Bruno J.F., 2010. A global analysis of the effectiveness of marine protected areas in preventing coral loss. PLoS ONE 5: e9278. https://doi.org/10.1371/journal.pone.0009278 , Leleu et al. 2012Leleu K., Remy-Zephir B., Grace R. et al. 2012. Mapping habitats in a marine reserve showed how a 30-year trophic cascade altered ecosystem structure. Biol. Conserv. 155: 193-201. https://doi.org/10.1016/j.biocon.2012.05.009 , Krueck et al. 2017Krueck N.C., Ahmadia G.N., Possingham H.P. et al. 2017. Marine reserve targets to sustain and rebuild unregulated fisheries. PLoS Biol. 15. https://doi.org/10.1371/journal.pbio.2000537 ). However, there remains scepticism towards using MPAs to achieve economic benefits, specifically regarding fisheries (Fletcher et al. 2015Fletcher W.J., Kearney R.E., Wise B.S., et al. 2015. Large-scale expansion of no-take closures within the Great Barrier Reef has not enhanced fishery production. Ecol. Appl. 25: 1187-1196. https://doi.org/10.1890/14-1427.1 , Hilborn 2017Hilborn R. 2017. Traditional fisheries management is the best way to manage weak stocks. Proc. Nat. Acad. Sci. 114: E10610-E10610. https://doi.org/10.1073/pnas.1715680114 , 2018Hilborn R. 2018. Are MPA effective? ICES J. Mar. Sci. 75: 1160-1162. https://doi.org/10.1093/icesjms/fsx068 ), as discussed below.

MPAs are widely accepted as the principal tool for protecting biodiversity and conserving threatened species, but their role in fisheries management is debated (Roberts et al. 2017Roberts C.M., O’Leary B.C., McCauley D.J. et al. 2017. Marine reserves can mitigate and promote adaptation to climate change. Proc. Nat. Acad. Sci. 114: 6167-6175. https://doi.org/10.1073/pnas.1701262114 , Pendleton et al. 2018Pendleton L.H., Ahmadia G.N., Browman H.I., et al. 2018. Debating the effectiveness of marine protected areas. ICES J. Mar. Sci. 75: 1156-1159. https://doi.org/10.1093/icesjms/fsx154 , Kriegl et al. 2021Kriegl M., Elías Ilosvay X.E., von Dorrien C. et al. 2021. Marine Protected Areas: At the crossroads of nature conservation and fisheries management. Front. Mar. Sci. 8: 676264. https://doi.org/10.3389/fmars.2021.676264 ). Critics argue that evidence of fisheries economic benefits resulting from MPAs are too context-dependent to draw robust conclusions about their efficacy as fisheries management tools (Hilborn et al. 2004Hilborn R., Stokes K., Maguire J.J., et al. 2004. When can marine reserves improve fisheries management? Ocean & Coast. Manag. 47: 197-205. https://doi.org/10.1016/j.ocecoaman.2004.04.001 , Di Franco et al. 2016Di Franco A., Thiriet P., Di Carlo G., et al. 2016. Five key attributes can increase Marine Protected Areas performance for small-scale fisheries management. Sci. Rep 6: 38135. https://doi.org/10.1038/srep38135 , Hughes et al. 2016Hughes T., Cameron D.S., Chin A., et al. 2016. A critique of claims for negative impacts of Marine Protected Areas on fisheries. Ecol. Appl. 26: 637-641. https://doi.org/10.1890/15-0457 ). They argue that there is a lack of evidence that MPAs benefit fisheries, for example, “…the evidence that MRs [Marine Reserves] substantially enhance fishery stocks is weak” (Caveen et al. 2015Caveen A., Polunin N., Gray T., et al. 2015. Critique of the scientific evidence for fisheries benefits of MRs. In: The controversy over marine protected areas: pp. 51-80, Springer, Cham. https://doi.org/10.1007/978-3-319-10957-2_5 ). Critics also argue that evidence of spillover is “…primarily anecdotal…” (Pantzar et al. 2018Pantzar M., Russi D., Hooper T. et al. 2018. Study on the Economic Benefits of Marine Protected Areas. Literature review analysis. Report to the European Commission. Europe: Executive Agency for Small and Medium-sized Enterprises (EASME).), that there is “no equivocal demonstration of spillover in fisheries adjacent to MPA” (Hargreaves-Allen 2020Hargreaves-Allen V.A. 2020. The economics of marine reserves. Oxford Research Encyclopedia of Environmental Science. https://doi.org/10.1093/acrefore/9780199389414.013.438 ), and that there is only mixed evidence that MPAs enhance larval export or spillover (Caveen et al. 2015Caveen A., Polunin N., Gray T., et al. 2015. Critique of the scientific evidence for fisheries benefits of MRs. In: The controversy over marine protected areas: pp. 51-80, Springer, Cham. https://doi.org/10.1007/978-3-319-10957-2_5 ). Others argue that fishing effort may increase outside the MPAs due to fishery displacement (Hilborn and Hilborn 2019Hilborn R., Hilborn U. 2019. Ocean Recovery: A sustainable future for global fisheries? Oxford University Press. https://doi.org/10.1093/oso/9780198839767.001.0001 , McConnaughey et al. 2020McConnaughey R.A., Hiddink J.G., Jennings S. et al. 2020. Choosing best practices for managing impacts of trawl fishing on seabed habitats and biota. Fish Fish. 21: 319-337. https://doi.org/10.1111/faf.12431 ), that MPAs provide few if any socio-economic benefits (Caveen et al. 2015Caveen A., Polunin N., Gray T., et al. 2015. Critique of the scientific evidence for fisheries benefits of MRs. In: The controversy over marine protected areas: pp. 51-80, Springer, Cham. https://doi.org/10.1007/978-3-319-10957-2_5 ) and that gear and catch restrictions provide better biodiversity protection than MPAs (Hilborn and Hilborn 2019Hilborn R., Hilborn U. 2019. Ocean Recovery: A sustainable future for global fisheries? Oxford University Press. https://doi.org/10.1093/oso/9780198839767.001.0001 , McConnaughey et al. 2020McConnaughey R.A., Hiddink J.G., Jennings S. et al. 2020. Choosing best practices for managing impacts of trawl fishing on seabed habitats and biota. Fish Fish. 21: 319-337. https://doi.org/10.1111/faf.12431 ). Such criticisms are frequently used to devalue the use of MPAs as fisheries management tools, without consideration of the factors that result in such outcomes or the success of MPAs in other settings. In all these cases, the examples to the contrary are regarded as exceptional or it is argued that the evidence supporting MPA benefits is not enough.

This opposition causes confusion and conflict between stakeholders, slowing progress towards ocean protection targets (Ballantine 2014Ballantine B. 2014. Fifty years on: lessons from marine reserves in New Zealand and principles for a worldwide network. Biol. Conserv. 176: 297-307. https://doi.org/10.1016/j.biocon.2014.01.014 , Manson et al. 2021Manson P., Nielsen-Pincus M., Granek E.F. et al. 2021. Public perceptions of ocean health and marine protection: Drivers of support for Oregon’s marine reserves. Ocean Coast. Manag. 201: 105480. https://doi.org/10.1016/j.ocecoaman.2020.105480 ). As economic benefits, food security and other ecosystem services are underpinned by the restoration and bolstering of ecological functions, failure to adequately protect marine biodiversity and important habitats continues to undermine the economic and environmental sustainability of the world’s oceans. Here, the evidence for benefits of MPAs to the economic activities of fisheries and tourism are reviewed. Google Scholar was searched using the key words “economic”, “value”, “MPA”, “marine protected area”, “marine reserve”, “fisheries” and “tourism”, and the first 200 records were reviewed to find empirical measurements of economic value to fisheries or tourism.

FISHERIES

Of the 51 MPAs reviewed here: 35% (18) were less than 10 years old and 22% (11) were more than 20 years old. Benefits to adjacent finfish, crustacean and mollusc fisheries were detected in 46 (90%) of the MPAs, including an increased fishery catch (76%) and body size (25%), and detection of spillover (16%) (Table 1). The latter three percentages exceed 100% because some examples showed several effects. Economic benefits to fisheries from MPAs were reported for 25 countries (plus two overseas territories), spanning temperate, sub-tropical and tropical seas in the North Atlantic, North Pacific, South Pacific and Indian Oceans (Fig. 1). The MPAs encompassed a variety of ecosystems, including coral reefs, kelp forests, mangroves, rocky reefs, salt marshes, mudflats and sandy and muddy seabeds. The MPAs employed a variety of protection methods, including multi-use zones, temporary and permanent closures, restrictions on destructive gear types, and bans on boat-based fishing. The use of no-take MPAs, hereafter called marine reserves, consistently showed the largest benefits.

Fisheries close to MPAs had up to 45 times higher catch per unit effort (CPUE) and 40 times higher catch (Table 1). In one study, fish size was on average 34% greater (Beets and Friedlander 1999Beets J., Friedlander A. 1999. Evaluation of a conservation strategy: a spawning aggregation closure for red hind, Epinephelus guttatus, in the US Virgin Islands. Environ. Biol. Fish. 55: 91-98. https://doi.org/10.1023/A:1007404421518 ), and in another, larval export was enhanced, showing no decreasing trend up to 40 km away (Le Port et al. 2017Le Port A., Montgomery J.C., Smith A.N.H. et al. 2017. Temperate Marine Protected Area provides recruitment subsidies to local fisheries. Proc. R. Soc. B: Biol. Sci. 284 (1865): 20171300. https://doi.org/10.1098/rspb.2017.1300 ) (Table 1). Another MPA showed increased juvenile recruitment up to the 1000 km² limit of the study area (Harrison et al. 2012Harrison H.B., Williamson D.H., Evans R.D., et al. 2012. Larval export from marine reserves and the recruitment benefit for fish and fisheries. Curr. Biol. 22: 1023-1028. https://doi.org/10.1016/j.cub.2012.04.008 ). Fish behaviour can also change, with reduced flight initiation distance within an MPA, making fish easier to observe (Costello 2014Costello M.J. 2014. Long live Marine Reserves: A review of experiences and benefits. Biol. Conserv. 176: 289-296. https://doi.org/10.1016/j.biocon.2014.04.023 , Januchowski-Hartley et al. 2014Januchowski-Hartley F.A. et al. 2014. Fishery benefits from behavioural modification of fishes in periodically harvested fisheries closures. Aquat. Conserv.: Mar. Freshwat. Ecosys. 24: 777-790. https://doi.org/10.1002/aqc.2388 ). MPAs with varying levels of protection, such as those with partial protection areas and fishery closures, also provided significant advantages for fishermen. Yamasaki et al. (2002)Yamasaki A. 2002. Establishment of preserved area for snow crab Chionoecetes opilio and consequent recovery of the crab resources. Fish. Sci. 68: 1699-1702. https://doi.org/10.2331/fishsci.68.sup2_1699 found a nearly four-fold increase in catch volumes, Vandeperre et al. (2011)Vandeperre F., Higgins R.M., Sánchez-Meca J. et al. 2011. Effects of no-take area size and age of marine protected areas on fisheries yields: a meta-analytical approach. Fish Fish. 12: 412-426. https://doi.org/10.1111/j.1467-2979.2010.00401.x showed an increase in CPUE of 60%-120% over 30 years, and Kerwath et al. (2013)Kerwath S.E., Winker H., Götz A. et al. 2013. Marine Protected Area improves yield without disadvantaging fishers. Nature Comm. 4: 1-6. https://doi.org/10.1038/ncomms3347 found that CPUE doubled after 10 years of protection. In total, 32 studies found increased catch since MPA designation.

Some of the studies indicated economic advantages to fisheries due to increases in fish size and consequently fecundity (Table 1), as predicted by modelling (De Leo and Micheli 2015De Leo G.A., Micheli F. 2015. The good: the bad and the ugly of marine reserves for fishery yields. Phil. Trans. R. Soc. B: Biol. Sci. 370 (1681): 20140276. https://doi.org/10.1098/rstb.2014.0276 ). These outcomes may not directly contribute to catch increases, but they help sustain fisheries adjacent to protected areas within larval dispersal ranges through increased recruitment, as, for example, was found by Le Port et al. (2017)Le Port A., Montgomery J.C., Smith A.N.H. et al. 2017. Temperate Marine Protected Area provides recruitment subsidies to local fisheries. Proc. R. Soc. B: Biol. Sci. 284 (1865): 20171300. https://doi.org/10.1098/rspb.2017.1300 , Pelc et al. (2009Pelc R.A., Baskett M.L., Tanci T., et al. 2009. Quantifying larval export from South African marine reserves. Mar. Ecol. Progr. Ser. 394: 65-78. https://doi.org/10.3354/meps08326 , 2010)Pelc R.A., Warner R.R., Gaines S.D. et al. 2010. Detecting larval export from marine reserves. Proc. Nat. Acad. Sci. 107 (43): 18266-18271. https://doi.org/10.1073/pnas.0907368107 and Harrison et al. (2012)Harrison H.B., Williamson D.H., Evans R.D., et al. 2012. Larval export from marine reserves and the recruitment benefit for fish and fisheries. Curr. Biol. 22: 1023-1028. https://doi.org/10.1016/j.cub.2012.04.008 . Harrison et al. (2012)Harrison H.B., Williamson D.H., Evans R.D., et al. 2012. Larval export from marine reserves and the recruitment benefit for fish and fisheries. Curr. Biol. 22: 1023-1028. https://doi.org/10.1016/j.cub.2012.04.008 showed that reserves covering only 28% of the reef area produced half of all juvenile recruitment, and Le Port et al. (2017)Le Port A., Montgomery J.C., Smith A.N.H. et al. 2017. Temperate Marine Protected Area provides recruitment subsidies to local fisheries. Proc. R. Soc. B: Biol. Sci. 284 (1865): 20171300. https://doi.org/10.1098/rspb.2017.1300 found that a small (5.2 km²) reserve in New Zealand contributed over 10% of juveniles to the surrounding areas. Qu et al. (2021)Qu Z., Thrush S., Parsons D. et al. 2021. Economic valuation of the snapper recruitment effect from a well-established temperate no-take marine reserve on adjacent fisheries. Mar. Pol. 134: 104792. https://doi.org/10.1016/j.marpol.2021.104792 valued the snapper recruitment effect noted by Le Port et al. (2017)Le Port A., Montgomery J.C., Smith A.N.H. et al. 2017. Temperate Marine Protected Area provides recruitment subsidies to local fisheries. Proc. R. Soc. B: Biol. Sci. 284 (1865): 20171300. https://doi.org/10.1098/rspb.2017.1300 at NZ$5 million (~US$ 3 million) per annum to local commercial fisheries, a considerable economic gain.

Two studies did not find unambiguous fishery benefits in terms of gross fish catch. In one case the MPA was only established for 4.5 years and a decline in catch could have been due to one year of poor recruitment of one fish species (Smith et al. 2006Smith M.D., Zhang J., Coleman F.C. 2006. Effectiveness of marine reserves for large-scale fisheries management. Can. J. Fish. Aquat. Sci. 63: 153-164. https://doi.org/10.1139/f05-205 ), and the same authors subsequently found no decline in catch (Smith et al. 2007Smith M.D., Zhang J., Coleman F.C. 2007. Structural modeling of marine reserves with Bayesian estimation. Mar. Res. Econ. 22: 121-136. https://doi.org/10.1086/mre.22.2.42629548 ). In the second, there was stable or increasing CPUE following closure of 33% of the area to fishing and a 30% decline in effort due to 6 of 13 fisheries having some licences bought out (Fletcher et al. 2015Fletcher W.J., Kearney R.E., Wise B.S., et al. 2015. Large-scale expansion of no-take closures within the Great Barrier Reef has not enhanced fishery production. Ecol. Appl. 25: 1187-1196. https://doi.org/10.1890/14-1427.1 ). However, this study did not account for management measures to reduce overfishing and geographic variation in fisheries and environmental factors (e.g. typhoons) (Hughes et al. 2016Hughes T., Cameron D.S., Chin A., et al. 2016. A critique of claims for negative impacts of Marine Protected Areas on fisheries. Ecol. Appl. 26: 637-641. https://doi.org/10.1890/15-0457 ). Because it was surprising that no studies showed losses to fisheries, we also polled the ~12000 members of the “MPA Help” community (https://octogroup.org/programs/mpa-help/) for evidence of such costs. However, the responses could only provide studies on estimated or modelled costs to fisheries, not demonstrated costs. This indicates that if there are any net losses to any fisheries anywhere due to MPAs, they are not documented and likely rare.

There are many reasons why a fishery may or may not benefit from an MPA, as reviewed by Gaines et al. (2010)Gaines S.D., White C., Carr M.H., et al. 2010. Designing marine reserve networks for both conservation and fisheries management. Proc. Nat. Acad. Sci. 107: 18286-18293. https://doi.org/10.1073/pnas.0906473107 . Inverted logic often regards MPAs as the “experiment” or “treatment”, whereas the MPA is the control or reference for the experiments that study the human activities outside it. Comparisons inside and outside indicate two-thirds of rocky and coral reef fishes have been removed by fishing (Edgar et al. 2014Edgar G.J., Stuart-Smith R.D., Willis T.J., et al. 2014. Global conservation outcomes depend on Marine Protected Areas with five key features. Nature 506 (7487): 216-220. https://doi.org/10.1038/nature13022 ). Assessing the impact of these activities requires not only controls (i.e. marine reserves), but data on their direct effect on target species abundance, body size and age, and associated habitat damage, plus data on the indirect effects on food webs, such as those due to trophic cascades (Costello et al. 2022Costello M.J. Gordó-Vilaseca C., Coll M. 2022. Trophic Cascades and Marine Reserves: dual indicators of fishery and climate change disruption in pelagic and benthic ecosystems. In: Imperiled: The Encyclopedia of Conservation, Elsevier, 903-911. https://doi.org/10.1016/B978-0-12-821139-7.00234-8 ). The variation associated with fishing effort and gear makes quantifying fishing impact and CPUE difficult (Smith et al. 2006Smith M.D., Zhang J., Coleman F.C. 2006. Effectiveness of marine reserves for large-scale fisheries management. Can. J. Fish. Aquat. Sci. 63: 153-164. https://doi.org/10.1139/f05-205 ). Furthermore, fishing pressure-be it commercial, recreational, or both-may often continue to increase in the area regardless of the establishment of an MPA (e.g. Nillos Kleiven et al. 2019Nillos Kleiven P.J., Espeland S.H., Olsen E.M., et al. 2019. Fishing pressure impacts the abundance gradient of European lobsters across the borders of a newly established Marine Protected Area. Proc. R. Soc. B 286 (1894): 20182455. https://doi.org/10.1098/rspb.2018.2455 , Kleiven 2020Kleiven A.R., Moland, E., Sumaila U.R. 2020. No fear of bankruptcy: the innate self-subsidizing forces in recreational fishing. ICES J. Mar. Sci. 77: 2304-2307. https://doi.org/10.1093/icesjms/fsz128 , LaScala-Gruenewald et al. 2021LaScala-Gruenewald D.E., Grace R.V., Haggitt T.R., et al. 2021. Small marine reserves do not provide a safeguard against overfishing. Conserv. Sci. Pract. 3: e362. https://doi.org/10.1111/csp2.362 ).

TOURISM

Examples of economic benefits from tourism were found in 24 countries, of which the majority were in tropical and sub-tropical locations, with four examples from temperate regions (France, Spain, Italy and New Zealand) (Fig. 2, Table 2). MPAs were located in the Indian, North Atlantic, North Pacific and South Pacific Oceans. The MPAs which showed benefits to tourism covered a range of ecosystems, including rocky reefs, kelp forests and sandy and muddy bottoms, but were dominated by coral reefs, mangroves and seagrass ecosystems. These 31 examples (Table 2) reported benefits to local communities, private companies, NGOs and state departments directly through user fees and indirectly through related expenses such as transport, accommodation, food, goods and other services. Shark diving contributes about $18 million a year to the economy of Palau, whereas shark fishing would contribute only $10800 (Vianna et al. 2012Vianna G.M.S., Meekan M.G., Pannell D.J., et al. 2012. Socio-economic value and community benefits from shark-diving tourism in Palau: a sustainable use of reef shark populations. Biol. Conserv. 145: 267-277. https://doi.org/10.1016/j.biocon.2011.11.022 ).

Individual MPAs have generated millions to billions of dollars in tourism revenue per year (Table 2). The Great Barrier Reef Marine Park, Australia, generated US$6.4 billion, and others generate hundreds of millions, such as the Galápagos Marine Reserve, Ecuador; Mu Ko Phi Phi Marine National Park, Thailand; and Ras Mohammed National Park, Red Sea, Egypt (Table 2). Some MPAs obtained millions of dollars from user fees (including fines), including Bonaire National Marine Park, Ras Mohammed National Park and the Wadi El Gemal-Hamata Protected Area. However, many MPAs, such as in New Zealand, do not charge visitor fees. In general, older, more established MPAs provided higher total tourism revenues, as shown by the Great Barrier Reef Marine Park, Mu Ko Phi Phi Marine National Park, Ras Mohammed National Park and the Bahamas Shark Sanctuary (Fig. 3).

REBUTTAL OF CRITICISMS

Any sample of the literature will be biased by what research was conducted and published. However, the present sample provides no indications of significant costs to fisheries from establishment of MPAs. Indeed, there were 77 examples of evidence that MPAs can provide economic benefits through fisheries (n=46) and tourism (n=31) (Tables 1, 2). Evidently, MPAs can provide a rare win-win strategy for ocean management, enabling conservation and long-term economic goals to be achieved simultaneously.

Contrary to Caveen et al. (2015)Caveen A., Polunin N., Gray T., et al. 2015. Critique of the scientific evidence for fisheries benefits of MRs. In: The controversy over marine protected areas: pp. 51-80, Springer, Cham. https://doi.org/10.1007/978-3-319-10957-2_5 , MPAs are shown to substantially increase fish stocks and catch, and can provide sometimes lucrative socio-economic benefits (Tables 1, 2, Fig. 3). Another criticism of MPAs is that there is little or only anecdotal evidence of spillover from MPAs to fished areas (Caveen et al. 2015Caveen A., Polunin N., Gray T., et al. 2015. Critique of the scientific evidence for fisheries benefits of MRs. In: The controversy over marine protected areas: pp. 51-80, Springer, Cham. https://doi.org/10.1007/978-3-319-10957-2_5 , Pantzar et al. 2018Pantzar M., Russi D., Hooper T. et al. 2018. Study on the Economic Benefits of Marine Protected Areas. Literature review analysis. Report to the European Commission. Europe: Executive Agency for Small and Medium-sized Enterprises (EASME)., Hargreaves-Allen 2020Hargreaves-Allen V.A. 2020. The economics of marine reserves. Oxford Research Encyclopedia of Environmental Science. https://doi.org/10.1093/acrefore/9780199389414.013.438 ). However, the majority of examples of fisheries benefits from MPAs refer to the spillover of target species.

It may seem counter-intuitive that restricting fishing in an area will result in more fish elsewhere. Yet, this happens because marine life disperses from its safe haven (the MPA), which acts like a reservoir to replenish adjacent fisheries. In financial terms, the capital is invested and people benefit from the interest on the investment. To count MPAs as a cost to fisheries is analogous to claiming that interest earned on money is a cost. The evidence of this benefit is unequivocal (Table 1).

The fact that there were only four examples of larval export from MPAs reflects the practical challenges in distinguishing eggs and larvae from MPA vs non-MPA parents. Nevertheless, rather than there being mixed evidence of enhanced larval export (as suggested by Caveen et al. 2015Caveen A., Polunin N., Gray T., et al. 2015. Critique of the scientific evidence for fisheries benefits of MRs. In: The controversy over marine protected areas: pp. 51-80, Springer, Cham. https://doi.org/10.1007/978-3-319-10957-2_5 ), the evidence collected to date supports predictions that MPAs contribute disproportionately to larval dispersal (Pelc et al. 2010Pelc R.A., Warner R.R., Gaines S.D. et al. 2010. Detecting larval export from marine reserves. Proc. Nat. Acad. Sci. 107 (43): 18266-18271. https://doi.org/10.1073/pnas.0907368107 , Freeman et al. 2022Freeman J.B., Semmens, B.X., Thompson A.R. 2022. Impacts of Marine Protected Areas and the environment on larval rockfish species richness and assemblage structure in the Southern California Bight. Mar. Ecol. Progr. Ser. 698: 125-137. https://doi.org/10.3354/meps14161 ) and subsequent fisheries recruitment, further enhancing their worth as fisheries management tools (Hastings and Botsford 1999Hastings A., Botsford L.W. 1999. Equivalence in yield from marine reserves and traditional fisheries management. Science 284 (5419): 1537-1538. https://doi.org/10.1126/science.284.5419.1537 , De Leo and Micheli 2015De Leo G.A., Micheli F. 2015. The good: the bad and the ugly of marine reserves for fishery yields. Phil. Trans. R. Soc. B: Biol. Sci. 370 (1681): 20140276. https://doi.org/10.1098/rstb.2014.0276 , Kough et al. 2019Kough A.S., Belak C.A., Paris C.B. et al. 2019. Ecological spillover from a Marine Protected Area replenishes an over-exploited population across an island chain. Conserv. Sci. Pract. 1: e17. https://doi.org/10.1111/csp2.17 ).

Recent research has elaborated further on the fisheries benefits of protected areas arising frorm the increased size and fecundity of fish within MPA boundaries (Barneche et al. 2019Barneche D.R., Rezende E.L., Parravicini V., et al. 2019. Body size, reef area and temperature predict global reef-fish species richness across spatial scales. Global Ecol. Biogeog. 28: 315-327. https://doi.org/10.1111/geb.12851 , Marshall et al. 2021Marshall D.J., Bode M., Mangel M., et al. 2021. Reproductive hyperallometry and managing the world’s fisheries. Proc. Nat. Acad. Sci. 118 (34): e2100695118. https://doi.org/10.1073/pnas.2100695118 ). As protected areas increase fish size by an average of 28% (Lester et al. 2009Lester S.E., Halpern B.S., Grorud-Colvert K., et al. 2009. Biological effects within no-take marine reserves: a global synthesis. Mar. Ecol. Progr. Ser. 384: 33-46. https://doi.org/10.3354/meps08029 ), and the reproductive output of fish increases disproportionately with size and weight, the reproductive contribution of fish within protected areas has been systematically underestimated (Marshall et al. 2019Marshall D.J., Gaines S., Warner R,, et al. 2019. Underestimating the benefits of Marine Protected Areas for the replenishment of fished populations. Front. Ecol. Environ. 17: 407-413. https://doi.org/10.1002/fee.2075 ). Consequently, establishing protected reservoirs of Big Old Fat Fecund Female Fish (BOFFFFs) can lead to increased larvae diversity in the plankton (Freeman et al. 2022Freeman J.B., Semmens, B.X., Thompson A.R. 2022. Impacts of Marine Protected Areas and the environment on larval rockfish species richness and assemblage structure in the Southern California Bight. Mar. Ecol. Progr. Ser. 698: 125-137. https://doi.org/10.3354/meps14161 ) and enhance fishery yields (Marshall et al. 2019Marshall D.J., Gaines S., Warner R,, et al. 2019. Underestimating the benefits of Marine Protected Areas for the replenishment of fished populations. Front. Ecol. Environ. 17: 407-413. https://doi.org/10.1002/fee.2075 ). This highlights the importance of keeping BOFFFFs within breeding populations and also shows that a failure to consider reproductive hyper-allometry overestimates the effectiveness of traditional fisheries management (Marshall et al. 2021Marshall D.J., Bode M., Mangel M., et al. 2021. Reproductive hyperallometry and managing the world’s fisheries. Proc. Nat. Acad. Sci. 118 (34): e2100695118. https://doi.org/10.1073/pnas.2100695118 ). These important findings further strengthen the use of protected areas as fisheries management tools. Were fishermen given custodianship of fish stocks, then, like farmers, they might favour strict protection of broodstock in no-take MPAs.

Some authors have speculated that the implementation of MPAs reduces access to fisheries, resulting in lower catches and revenues for fishermen (e.g. Fletcher et al. 2015Fletcher W.J., Kearney R.E., Wise B.S., et al. 2015. Large-scale expansion of no-take closures within the Great Barrier Reef has not enhanced fishery production. Ecol. Appl. 25: 1187-1196. https://doi.org/10.1890/14-1427.1 and Chan 2020Chan H. 2020. Economic impacts of Papahānaumokuākea Marine National Monument expansion on the Hawaii longline fishery. Mar. Pol. 115: 103869. https://doi.org/10.1016/j.marpol.2020.103869 ). Such studies are sometimes cited as examples of MPAs displacing fishing and negatively impacting resource users. However, the findings of the former have been brought into question by Pecl et al. (2010)Pelc R.A., Warner R.R., Gaines S.D. et al. 2010. Detecting larval export from marine reserves. Proc. Nat. Acad. Sci. 107 (43): 18266-18271. https://doi.org/10.1073/pnas.0907368107 and Hughes et al. (2016Hughes T., Cameron D.S., Chin A., et al. 2016. A critique of claims for negative impacts of Marine Protected Areas on fisheries. Ecol. Appl. 26: 637-641. https://doi.org/10.1890/15-0457 ), and the latter has been disproved by research using empirical rather than modelled results, showing that catch and CPUE increased following MPA expansion (Lynham et al. 2020Lynham J., Costello C., Gaines S.D. et al. 2020. Impact of two of the world’s largest protected areas on longline fishery catch rates. Nature Comm. 11: 1-9. https://doi.org/10.1038/s41467-020-14588-3 ). Hilborn and Hilborn (2019)Hilborn R., Hilborn U. 2019. Ocean Recovery: A sustainable future for global fisheries? Oxford University Press. https://doi.org/10.1093/oso/9780198839767.001.0001 and McConnaughey et al. (2020)McConnaughey R.A., Hiddink J.G., Jennings S. et al. 2020. Choosing best practices for managing impacts of trawl fishing on seabed habitats and biota. Fish Fish. 21: 319-337. https://doi.org/10.1111/faf.12431 contended that MPAs displace fishing effort, and that this displaced fishing effort then drives down abundance in neighbouring areas, but without evidence of such effects. Indeed, depending on fishery management policies, fishing effort may be displaced, but we found no evidence of any consequent declines in fish abundance or catch outside MPAs. This may be because:

It is a credit to how MPAs have been designed and implemented that MPAs have generally benefited fisheries.

Yet, many MPAs are poorly funded to properly manage and enforce full protection of biodiversity; i.e. too many are “paper parks” (Relano and Pauly 2023Relano V, Pauly D. 2023. The ‘Paper Park Index’: Evaluating Marine Protected Area effectiveness through a global study of stakeholder perceptions. Mar. Pol. 151: 105571. https://doi.org/10.1016/j.marpol.2023.105571 ). Were more MPAs better planned, funded and consequently managed, we would likely see more widespread benefits to biodiversity, including fisheries and people (Fig. 4). The examples in this paper (Table 1, 2) should inspire improved management. The emerging benefits to society will in turn inspire local communities to establish more marine reserves.

Several studies estimated negligible fishery losses from the creation of MPAs. For example, the likely costs to fisheries of expanding MPAs in Northern Ireland ranged from £0 to £6000 per annum per proposed MPA (Department of Agriculture, Environment and Rural Affairs of Northern Ireland 2020Department of Agriculture, Environment and Rural Affairs of Northern Ireland. 2020. Consultation on the development of fisheries management measures for Marine Protected Areas and establishment of Scallop enhancement sites in the Northern Ireland inshore region. November 2020. Accessed https://www.daera-ni.gov.uk/consultations/consultation-development-fisheries-management-measures-marine-protected-areas-MPA-and-establishment on 30 July 2023.); up to 3.8% loss of income was reported from new MPAs in the Oregon Territorial Sea (The Research Group LLC 2021The Research Group LLC. 2021. Interactive model user guide for the broadscale spatial analysis of Oregon nearshore fisheries. Update 2017-2019 Base Period. Prepared for the Marine Reserve Program and Marine Resources Program, Oregon Department of Fish and Wildlife. 53 pp.); and it was reported that MPA expansion to 30% of the Seychelles EEZ would have a negligible impact on the tuna fishery because the areas only contributed 4% of the catch (Chassot et al. 2018Chassot E., Guillotreau P., Gastineau B. 2018. Economic value assessment of Seychelles tuna fisheries. Publication prepared for The Nature Conservancy. Submitted to the Seychelles Marine Spatial Plan Initiative and Government of Seychelles. University of Nantes and Capacités, France, 57 pp.). If fisheries are already operating in an ecologically sustainable manner, with negligible effect on biodiversity, then creating MPAs may confirm this, and no fishery benefits would be evident, as suggested in a study on the Great Barrier Reef fisheries (Fletcher et al. 2015Fletcher W.J., Kearney R.E., Wise B.S., et al. 2015. Large-scale expansion of no-take closures within the Great Barrier Reef has not enhanced fishery production. Ecol. Appl. 25: 1187-1196. https://doi.org/10.1890/14-1427.1 ).

Regardless of the reason, not only do claims of fishery displacement effects not seem to have impacted fisheries, but the evidence shows that MPAs sustain or increase catch in adjacent areas (Table 1). Rather than negatively affecting fish catch through the displacement of fishing effort, ‘fishing-the-line’, where commercial and recreational fishermen concentrate fishing effort along MPA boundaries, has been shown to increase yield and provide greater catches of larger individuals, and is a well-known practice among fishermen (Kelly et al. 2002Kelly S., Scott D., MacDiarmid A.B. 2002. The value of a spillover fishery for spiny lobsters around a marine reserve in northern New Zealand. Coast. Manag. 30: 153-166. https://doi.org/10.1080/089207502753504689 , Goñi et al. 2006Goñi R., Quetglas A., Reñones O. 2006. Spillover of spiny lobsters Palinurus elephas from a marine reserve to an adjoining fishery. Mar. Ecol. Progr. Ser. 308: 207-219. https://doi.org/10.3354/meps308207 , Boerder et al. 2017Boerder K., Bryndum-Buchholz A., Worm B. 2017- Interactions of tuna fisheries with the Galápagos marine reserve. Mar. Ecol. Progr. Ser. 585: 1-15. https://doi.org/10.3354/meps12399 , personal observation). A metanalysis found fish abundance and biomass increase by 33% and 54%, respectively, immediately outside 23 MPAs (Di Lorenzo et al. 2016Di Lorenzo M., Claudet J., Guidetti P. 2016. Spillover from Marine Protected Areas to adjacent fisheries has an ecological and a fishery component. J. Nat. Conserv. 32: 62-66. https://doi.org/10.1016/j.jnc.2016.04.004 ). MPAs increase resilience to fishing, as shown by their ability to sustain consistent catches while subject to intense fishing pressure along their boundaries (Stelzenmüller et al. 2008Stelzenmüller V., Maynou F., Bernard G., et al. 2008. Spatial assessment of fishing effort around European marine reserves: implications for successful fisheries management. Mar. Poll. Bull. 56: 2018-2026. https://doi.org/10.1016/j.marpolbul.2008.08.006 , Stobart et al. 2009Stobart B., Warwick R., González C., et al. 2009. Long-term and spillover effects of a Marine Protected Area on an exploited fish community. Mar. Ecol. Progr. Ser. 384: 47-60. https://doi.org/10.3354/meps08007 , da Silva et al. 2015da Silva I. M., Hill N., Shimadzu H., et al. 2015. Spillover effects of a community-managed marine reserve. PLoS ONE 10, e0111774. https://doi.org/10.1371/journal.pone.0111774 , Harasti et al. 2018Harasti D., Fedler T., Brooks E.J. 2018. Increase in relative abundance and size of snapper Chrysophrys auratus within partially-protected and no-take areas in a temperate marine protected area. Front. Mar. Sci. 5: 208. https://doi.org/10.3389/fmars.2018.00208 ). This displacement of fishing effort to reserve boundaries and neighbouring areas may also enhance fish stock availability and stabilize local catches, depending on the relative size of the MPA, as shown for far-ranging pelagic species such as tuna (Boerder et al. 2017Boerder K., Bryndum-Buchholz A., Worm B. 2017- Interactions of tuna fisheries with the Galápagos marine reserve. Mar. Ecol. Progr. Ser. 585: 1-15. https://doi.org/10.3354/meps12399 ).

Gear and catch restrictions can reduce impacts on biodiversity, but Hilborn’s (2016)Hilborn R. 2016. Policy: Marine biodiversity needs more than protection. Nature 535: 224-226. https://doi.org/10.1038/535224a claim that these fishery regulations offer more protection than MPAs is only true when compared with partly protected areas which still allow fishing. Furthermore, most commercial and recreational fishing methods, including hook and line and pots, can kill species of seabirds, mammals, turtles and fish which are already threatened with extinction. Although changes in fishing gear can be successful at reducing bycatch, they do not eliminate it, and technological advances in fishing gear that may reduce bycatch have been slow to be adopted. Furthermore, contrary to assertions by McConnaughey et al. (2020)McConnaughey R.A., Hiddink J.G., Jennings S. et al. 2020. Choosing best practices for managing impacts of trawl fishing on seabed habitats and biota. Fish Fish. 21: 319-337. https://doi.org/10.1111/faf.12431 , limiting (but not banning) trawl fishing effort cannot have more positive effects on benthic biota than the implementation of MPAs, because bottom trawls destroy biogenic habitats, some created by species with life spans of centuries (Hiddink et al. 2017Hiddink J.G., Jennings S., Sciberras M. et al. 2017. Global analysis of depletion and recovery of seabed biota after bottom trawling disturbance. Proc. Nat. Acad. Sci. 114: 8301-8306. https://doi.org/10.1073/pnas.1618858114 ). In contrast, MPAs enable the natural recovery of benthic habitats and commercial species (Gell and Roberts 2003Gell F.R., Roberts C.M. 2003. Benefits beyond boundaries: the fishery effects of marine reserves. Trends Ecol. Evol. 18: 448-455. https://doi.org/10.1016/S0169-5347(03)00189-7 , Stewart et al. 2020).

The economic benefits of MPAs can be numerous (Tables 1, 2). However, stakeholder negotiation during the design process can lead to MPAs being placed in areas where there is little fishing and low biodiversity, as well as to reductions in protected area size, shape and the level of protection provided (Helson et al. 2010Helson J., Leslie S., Clement G. et al. 2010. Private rights, public benefits: Industry-driven seabed protection. Mar. Pol. 34: 557-566. https://doi.org/10.1016/j.marpol.2009.11.002 , Magris and Pressey 2018Magris R.A., Pressey R.L. 2018. Marine Protected Areas: Just for show? Science 360 (6390): 723-724. https://doi.org/10.1126/science.aat6215 , Kuempel et al. 2019Kuempel C.D., Jones K.R., Watson J.E. et al. 2019. Quantifying biases in marine-protected-area placement relative to abatable threats. Conserv. Biol. 33: 1350-1359. https://doi.org/10.1111/cobi.13340 ). Sometimes, due to anticipated opposition, MPA boundaries and locations are not designed to maximize benefits to biodiversity and fisheries, but instead are based on political processes that prioritize public acceptance or logistics, ignoring or downgrading ecological and biological aims (Devillers et al. 2015Devillers R., Pressey R.L., Grech A., et al. 2015. Reinventing residual reserves in the sea: are we favouring ease of establishment over need for protection? Aquat. Conserv. Mar. Freshwat. Ecosys. 25: 480-504. https://doi.org/10.1002/aqc.2445 , Lubchenco and Grorud-Colvert 2015Lubchenco J., Grorud-Colvert K. 2015. Making waves: The science and politics of ocean protection. Science 350 (6259): 382-383. https://doi.org/10.1126/science.aad5443 ). This reduces the potential benefits of MPAs, as all outcomes ultimately depend on ecological recovery. MPA design, attributes and stakeholder support play a large part in determining any benefits to fisheries and tourism (Di Franco et al. 2016Di Franco A., Thiriet P., Di Carlo G., et al. 2016. Five key attributes can increase Marine Protected Areas performance for small-scale fisheries management. Sci. Rep 6: 38135. https://doi.org/10.1038/srep38135 ), and poorly designed or enforced MPAs may not reap economic benefits (Campbell et al. 2012Campbell S.J., Hoey A.S., Maynard J., et al. 2012. Weak compliance undermines the success of no-take zones in a large government-controlled marine protected area. PLoS ONE 7: e50074. https://doi.org/10.1371/journal.pone.0050074 ). Were more MPAs selected to maximize fishery benefits, economic benefits might be even greater than those found here (Table 1). The evidence here strengthens arguments to design both partial-take MPAs and marine reserves to benefit both biodiversity and fisheries rather than shrink them into residual locations. Considering that many, perhaps most, MPAs are not established to benefit fisheries, it is noteworthy that so many show fishery benefits (Table 1).

There do not appear to be any studies demonstrating a clear economic cost to fisheries after the establishment of an MPA, only benefits. Balmford et al. (2004)Balmford A., Gravestock P., Hockley N., et al. 2004. The worldwide costs of marine protected areas. Proc. Nat. Acad. Sci. 101: 9694-9697. https://doi.org/10.1073/pnas.0403239101 estimated that a global MPA network may create 1 million jobs, and its $5-19 billion cost was less than the government subsidies to industrial fisheries, which only serve to postpone the eventual collapse of otherwise unsustainable fisheries and associated employment. They did not provide data on the costs of existing fisheries management, which are likely to be greater than the cost of MPA management (Anonymous 2023Anonymous. 2023. Sustainably financing Ireland’s Marine Protected Area Network. FairSeas, Cork, 88 pp. https://fairseas.ie/wp-content/uploads/2023/06/Fair-Seas-Sustainably-Financing-Irelands-Marine-Protected-Area-Network.pdf ), or estimate the benefits to fisheries. Similarly, a global analysis on the cost-benefits of expanding protected areas on land and sea found that the economic revenue would be $64 to £454 billion greater than that of not expanding them by 2050, and would avoid losses of $179 to £534 billion (Waldron et al. 2020Waldron A., Adams V., Allan J. et al. 2020. Protecting 30% of the planet for nature: costs, benefits, and economic implications: Working paper analysing the economic implications of the proposed 30% target for areal protection in the draft post-2020 Global Biodiversity Framework. Campaign for Nature, Conservation Science Group, University of Cambridge, UK, 58 pp.). Consequently, the expansion of MPAs, which promote sustainable management, could save money when compared with current fisheries management practices, particularly if the costs of existing fisheries management and subsidies are redistributed. Because of the simplicity of the management, marine reserves have lower management costs than partly protected MPAs and fishery areas (Anonymous 2023). Other studies have also estimated the varying costs of establishing and maintaining protected areas, but similarly do not place this in the context of existing costs in marine spatial management, or consider the costs of continuing the status quo (Jantke et al. 2018Jantke K., Jones K.R., Allan J.R., et al. 2018. Poor ecological representation by an expensive reserve system: evaluating 35 years of marine protected area expansion. Conserv. Lett. 11: e12584. https://doi.org/10.1111/conl.12584 ). Estimating the cost-benefits of MPAs to fisheries is complicated, but Brander et al (2020)Brander L.M., Van Beukering, P., Nijsten, L., et al. 2020. The global costs and benefits of expanding Marine Protected Areas. Mar. Pol. 116: 103953. https://doi.org/10.1016/j.marpol.2020.103953 conclude that expanding the global MPA network will reap benefits 1.4 to 2.7 times the costs.

In contrast to land-based agriculture and forestry, fisheries make no investment in habitat or broodstock management. The sea is a public not a private resource, and stakeholders include not only commercial fishermen but also people involved in subsistence and recreational fishing, sport, tourism, education, research, conservation, mining, mariculture and transport. Despite this, the financial costs of MPAs are frequently estimated prior to implementation. Thereafter, the level of protection and the area protected are often reduced, or a financial package is determined, to assuage the temporary loss of resource access to one group of stakeholders (Olsson et al. 2008Olsson P., Folke C., Hughes T.P. 2008. Navigating the transition to ecosystem-based management of the Great Barrier Reef, Australia. Proc. Nat. Acad. Sci. 105: 9489-9494. https://doi.org/10.1073/pnas.0706905105 , Clifton 2013Clifton J. 2013. Compensation, conservation and communities: an analysis of direct payments initiatives within an Indonesian marine protected area. Environ. Conserv. 40: 287-295. https://doi.org/10.1017/S0376892913000076 ). These measures are based on the assumption that wildlife within protected areas belongs to those who exploited it, whereas it is a public resource which the exploiters have not invested in. In fact, protected areas are a method of investing in ecosystem restoration and sustainability, which are the foundations of productive, profitable fisheries and a resource for present and future generations.

In addition to the lack of research on existing fisheries management costs, the environmental costs of fishing, from carbon emissions to the loss of biodiversity, are seldom found within the literature. In the few studies to estimate environmental costs, the release of greenhouse gases from seabed sediments by bottom trawling is significant (Sala et al. 2021Sala E., Mayorga J., Bradley D., et al. 2021. Protecting the global ocean for biodiversity, food and climate. Nature 592 (7854): 397-402. https://doi.org/10.1038/s41586-021-03371-z , Atwood et al. 2023Atwood T.B., Sala E., Mayorga J., et al. 2023. Reply to: Quantifying the carbon benefits of ending bottom trawling. Nature 617 (7960): E3-E5. https://doi.org/10.1038/s41586-023-06015-6 ). Conversely, using protected areas provides a management strategy that benefits biodiversity, which can in turn result in increased carbon capture and storage (Mariani et al. 2020Mariani G., Cheung W.W., Lyet A. et al. 2020. Let more big fish sink: Fisheries prevent blue carbon sequestration-half in unprofitable areas. Sci. Adv. 6 (44): eabb4848. https://doi.org/10.1126/sciadv.abb4848 , Luisetti et al. 2020Luisetti T., Ferrini S., Grilli G. et al. 2020. Climate action requires new accounting guidance and governance frameworks to manage carbon in shelf seas. Nature Comm. 11: 1-10. https://doi.org/10.1038/s41467-020-18242-w , Hutto et al. 2021Hutto S.H., Brown M., Francis E. 2021. Blue carbon in Marine Protected Areas: Part 1; A guide to understanding and increasing protection of blue carbon. National Marine Sanctuaries Conservation Science Series ONMS-21-07. U.S. Department of Commerce, National Oceanic and Atmospheric Administration, Office of National Marine Sanctuaries. Available at: sanctuaries.noaa.gov., Epstein and Roberts 2022Epstein G., Roberts C.M. 2022. Identifying priority areas to manage mobile bottom fishing on seabed carbon in the UK. PLoS Climate 1: e0000059. https://doi.org/10.1371/journal.pclm.0000059 ).

MPAs can also increase the resilience of biodiversity to climate change through harbouring more abundant and genetically diverse populations (Costello 2021Costello M.J. 2021. Biodiversity conservation through protected areas supports healthy ecosystems and resilience to climate change and other disturbances. In: Goldstein M.I., DellaSala, D.A. (Eds), Imperiled: The Encyclopedia of Conservation. Reference Module in Earth Systems and Environmental Sciences, Elsevier, ISBN 9780124095489, in press. https://doi.org/10.1016/B978-0-12-821139-7.00164-1 ). For example, studies on abalone in Baja California found that marine reserves enhance resilience to climate impacts in abalone populations, because unfished populations had a larger body size and greater egg production (Micheli et al. 2012Micheli F., Saenz-Arroyo A., Greenley A., et al. 2012. Evidence that marine reserves enhance resilience to climatic impacts. PLoS ONE 7: e40832. https://doi.org/10.1371/journal.pone.0040832 , Munguía-Vega et al. 2015Munguía-Vega A., Sáenz-Arroyo A., Greenley A.P., et al. 2015. Marine reserves help preserve genetic diversity after impacts derived from climate variability: Lessons from the pink abalone in Baja California. Global Ecol. Conserv. 4: 264-276. https://doi.org/10.1016/j.gecco.2015.07.005 ). More comprehensive economic studies could show additional positive economic benefits of MPAs because of their benefits to fisheries, carbon storage, reducing greenhouse gas emissions, and in some cases, tourism. Further research to address these knowledge gaps is needed.

CONCLUSIONS

Given recent criticism of MPAs, the challenges faced during their design and designation, and their frequent small size and sub-optimal location, one would expect their economic benefits to be hard to detect or negligible. But the evidence in the scientific literature is that they can provide economic benefits for fisheries and tourism (Tables 1, 2, Figs 1-3). The generality of these benefits across oceans, continents, countries and a diversity of habitats and ecosystems is clear. While such benefits may seem surprising because fishing has been reduced in an area, it is also common sense that unfished stocks will increase in abundance and spread to adjacent areas as adults, juveniles, larvae or eggs. Thus, sweeping dismissals of MPA economic benefits are unfounded.

Fisheries management already restricts fishing, sometimes with complete bans for years, so it partly already implements no-take MPAs without calling them MPAs. In some areas, widespread fishery controls, such as quota and gear restrictions, already restrict fishing more than MPAs, especially when most MPAs still allow some fishing. An analysis of marine reserves in Sweden found they complemented fishery management measures, but when reopened to fisheries even temporarily the benefits were promptly lost (Bergström et al. 2022Bergström U., Berkström C., Sköld M., et al. 2022. Long-term effects of no-take zones in Swedish waters. Aqua reports 2022:20. Swedish University of Agricultural Sciences, Lysekil, Sweden, 289 pp.).

MPAs represent a viable, low-tech, cost-effective strategy that can be used effectively for small to large areas (Roberts et al. 2017Roberts C.M., O’Leary B.C., McCauley D.J. et al. 2017. Marine reserves can mitigate and promote adaptation to climate change. Proc. Nat. Acad. Sci. 114: 6167-6175. https://doi.org/10.1073/pnas.1701262114 ). As such, they have proven highly successful, both for safeguarding marine biodiversity and ecosystem functioning, and more pertinently, for reversing fishery declines, securing food provisions and ecosystem services and enabling the sustainable exploitation of fisheries resources (Pitchford et al. 2007Pitchford J.W., Codling E.A., Psarra D. 2007. Uncertainty and sustainability in fisheries and the benefit of marine protected areas. Ecol. Model. 207: 286-292. https://doi.org/10.1016/j.ecolmodel.2007.05.006 , Jones et al. 2017Jones E.V., Macintosh D., Stead S. et al. 2017. How effective are MPA in conserving crab stocks? A comparison of fisheries and conservation objectives in three coastal MPA in Thailand. Ocean Coast. Manag. 149: 186-197. https://doi.org/10.1016/j.ocecoaman.2017.09.012 , Ortiz-Lozano et al. 2017Ortiz-Lozano L., Olivera-Vázquez L., Espejel I. 2017. Legal protection of ecosystem services provided by Marine Protected Areas in Mexico. Ocean Coast. Manag. 138: 101-110. https://doi.org/10.1016/j.ocecoaman.2017.01.017 ) (Table 1). Consequently, a review of 118 studies found that no-take, well enforced and older MPAs benefited human well-being (Ban et al. 2019Ban N.C., Gurney G.G., Marshall N.A., et al. 2019. Well-being outcomes of marine protected areas. Nature Sustain. 2 (6): 524-532. https://doi.org/10.1038/s41893-019-0306-2 ). MPAs that are accessible to the public and harbour biodiverse habitats and mega-fauna have been shown to generate huge incomes from tourism, providing increased revenue and improved living standards, while contributing significantly to national GDP (Vianna et al. 2012Vianna G.M.S., Meekan M.G., Pannell D.J., et al. 2012. Socio-economic value and community benefits from shark-diving tourism in Palau: a sustainable use of reef shark populations. Biol. Conserv. 145: 267-277. https://doi.org/10.1016/j.biocon.2011.11.022 , Sala et al. 2013Sala E., Costello C., Dougherty D., et al. 2013. A general business model for marine reserves. PLoS ONE 8: e58799. https://doi.org/10.1371/journal.pone.0058799 ) (Table 2). There is also a need to shift the conventional management of fisheries from commercial to include the wider socio-economic benefits to coastal communities (Pitcher and Lam 2015Pitcher T.J., Lam M.E. 2015. Fish commoditization and the historical origins of catching fish for profit. Marit. Stud. 14, 1-19. https://doi.org/10.1186/s40152-014-0014-5 ).

The literature shows that the largest benefits to fisheries (Table 1) and biodiversity come from the designation of marine reserves from which no marine life or materials can be removed (Lester and Halpern 2017, Friedlander et al. 2017Friedlander A.M., Golbuu Y., Ballesteros E., et al. 2017. Size, age, and habitat determine effectiveness of Palau’s Marine Protected Areas. PloS ONE. 12: e0174787. https://doi.org/10.1371/journal.pone.0174787 , Sala and Giakoumi 2017Sala E., Giakoumi S. 2017. No-take marine reserves are the most effective protected areas in the ocean. ICES J. Mar. Sci. 75: 1166-1168. https://doi.org/10.1093/icesjms/fsx059 ). This “Ballantine’s Law” after the “father of marine reserves” who championed the then radical idea that MPAs should be completely no-take and permanent following his leading the establishment of the first MPA in New Zealand (which now hosts 44 marine reserves) (Ballantine and Gordon 1979Ballantine W.J., Gordon D.P. 1979. New Zealand’s first marine reserve, Cape Rodney to Okakari point, Leigh. Biol. Conserv. 15: 273-280. https://doi.org/10.1016/0006-3207(79)90048-X , Ballantine 2014Ballantine B. 2014. Fifty years on: lessons from marine reserves in New Zealand and principles for a worldwide network. Biol. Conserv. 176: 297-307. https://doi.org/10.1016/j.biocon.2014.01.014 , Walls and Gordon 2017Walls K., Gordon D.P. 2017. Bill Ballantine (1937-2015), a father of marine reserves. Biol. Conserv. 211: 189-192. https://doi.org/10.1016/j.biocon.2017.04.012 ). Costello and Ballantine (2015)Costello M.J., Ballantine B. 2015. Biodiversity conservation should focus on no-take Marine Reserves: 94% of Marine Protected Areas allow fishing. Trends Ecol. Evol. 30: 507-509. https://doi.org/10.1016/j.tree.2015.06.011 found that 76% of coastal countries had not even one marine reserve, and today they occupy only ~3% of the global ocean (see http://www.mpatlas.org and https://navigatormap.org).

The fishing industry and fishing communities have much to gain from MPAs, but misconceptions perpetuated in the scientific literature are serving as barriers to their efficacy and implementation. Global analyses have prioritized where to locate MPAs to meet the calls by the Convention on Biological Diversity, the UN Convention on the Law of the Sea, and the International Union for Conservation of Nature for at least 30% of ocean habitats to be fully protected by 2030 (Zhao et al. 2020Zhao Q., Stephenson F., Lundquist C., et al. 2020. Where Marine Protected Areas would best represent 30% of ocean biodiversity. Biol. Conserv. 244: 108536. https://doi.org/10.1016/j.biocon.2020.108536 ). To achieve this, fishery scientists need to promote the use of MPAs as a strategy to support biodiversity, including “ecosystem-based management” of fisheries, and work with conservation scientists in order to realize the true capacity of MPAs for economic success (Costello et al. 2016bCostello M.J., Salmond A., Hikuroa D., et al. 2016b. Marine reserves: Sustainable fisheries need reserves. Nature 540 (7633): 341. https://doi.org/10.1038/540341e , Bergström et al. 2022Bergström U., Berkström C., Sköld M., et al. 2022. Long-term effects of no-take zones in Swedish waters. Aqua reports 2022:20. Swedish University of Agricultural Sciences, Lysekil, Sweden, 289 pp.) (Fig. 4). MPAs are our best strategy for reversing declining biodiversity and unsustainable fisheries, because business as usual for global fisheries is unsustainable.