Effective marine protection: what does the science say?

Fish are abundant in no-take Papahanaumokuakea Marine National Monument. Photo credit: Luiz Rocha/NOAA
Fish are abundant in no-take Papahanaumokuakea Marine National Monument. Photo credit: Luiz Rocha/NOAA

The pressing need for the creation of marine protected areas (MPAs) (sometimes called as marine reserves) is discussed often on the Ocean Views blog. MPAs and reserves can help ecosystems recover, provide climate refuges and even protect humans. So we know that marine protection has a huge potential to improve environmental outcomes. But the MPAs in existence today aren’t all the same. Some MPAs allow fishing, some don’t. Some are large, some are small. When policymakers and scientists decide to protect a marine area, there is no universal template to follow. However, a groundbreaking study last year by Edgar et al. analyzing the conservation benefits from 87 global MPAs has started to help us figure out what an MPA needs to accomplish its conservation goals.

The study, published in Nature, examined the impact of MPAs on fish by comparing MPAs to fished areas. Their results revealed that, unfortunately, many MPAs were no different from fished areas in terms of fish biomass and species richness. Fortunately, some MPAs showed dramatic increases in fish biomass and species richness. The news for sharks was particularly good for those MPAs, with increases of 1,990% compared to fished areas. And, most important, the researchers figured out the five basic characteristics that differentiated successful from unsuccessful MPAs.

These characteristics were simplified into the acronym NEOLI, which the authors explain means “no take, well enforced, old (>10 years), large (>100km2) and isolated by deep water or sand.” While these findings may not surprise those who follow ocean conservation issues, they are extremely important for two reasons. One, this study is more comprehensive than previous studies, considering all of the NEOLI factors at once, and the data from all the MPAs was collected according to the same methodology. Thus its results are more robust and allow us to better understand how different features of MPAs may work together to enhance conservation benefits. Two, MPA advocates often encounter significant resistance from opponents who reject the need to incorporate one or more NEOLI characteristics into proposed MPAs. The research provides some of the best scientific evidence yet that certain characteristics are essential for MPA design.

Of course, many of the objections to MPAs are not based on science, but rather on politics. Yet, this research quantifies the tradeoffs that will be made when MPAs are reduced in size, or when fishing is still allowed. Only those MPAs with 4 or 5 of the NEOLI characteristics were dramatically different from fished areas. MPAs with three characteristics showed some differences, but they weren’t as impressive. For example, MPAs with 3 NEOLI features had 30% more overall fish biomass than fished areas. But MPAs with 5 features had 244% higher fish biomass. Nevertheless, the study concludes that as long as MPAs can check off 4 of the NEOLI boxes, they should result in improved marine ecosystem health.

Other research on New Zealand’s system of no-take reserves reinforces these results. New Zealand has had some of its reserves for decades, and has seen two interesting benefits as a result. One of the most important ones was that the reserves allowed scientists to make discoveries about fish behavior and marine habitats that they could not have found out unless they had access to an area consistently protected from fishing.

While different MPAs might have different purposes or different goals, this research reinforces the value in ensuring that they are all designed based on the same basic principles. To me, setting aside large areas free from extractive activities has always just seemed like common sense. Many people will say that our ability to manage fisheries has improved dramatically over the past few decades, and it has. That doesn’t mean humans have perfected it, or that we have achieved (or even can achieve) complete mastery of complex marine ecosystems. We learn new things about the ocean and its species all the time. MPAs are our insurance policies against our own lack of knowledge (Donald Rumsfeld might call them unknown unknowns) and against climate and other environmental uncertainties. Science is now giving us the data we need to set up effective insurance policies for the ocean, both to protect our future and to improve our present. As we think about ocean conservation goals for 2015 (and beyond), I hope we can heed those lessons.