In 1962, at the First World Conference of National Parks in Seattle, U.S., Carleton Ray, a marine biologist at the University of Virginia, pleaded the cause of setting aside unmolested areas in the sea.
Man is using the sea at a great rate, polluting it, developing its borders, he said in one of the conference sessions. If we conservationists and biologists do not think of the planet as one earth and water then I ask, who will? If we do not press for marine as well as terrestrial sanctuaries and for regulations over our marine activities, then I ask again, who will?
This plea to begin establishing marine protected areas gained momentum over decades. At the 1992 Rio Earth Summit, for instance, countries agreed to maintain marine biodiversity by establishing networks of marine protected areas. Many scientists also began presenting evidence that fishing was causing the world’s fish stocks to collapse: Overfishing was pushing many marine species toward extinction and destroying or altering marine habitats. Creating marine protecting areas, they stressed, was the best approach to addressing this degradation of the marine environment.
In 2004, the world’s governments adopted their first tangible international target under the U.N. Convention on Biological Diversity (CBD): They committed to conserving at least 10 percent of coastal and marine areas by 2012. But when the coverage remained below 2 percent in 2010, the CBD extended the deadline to 2020.
Where there were only about 430 marine protected areas as of 1985, today there are more than 15,600 covering more than 25 million square kilometers (9.7 million square miles), or nearly 7 percent of the Earth’s oceans, according to the latest figures from the U.N.’s Protected Planet data repository.
Protecting marine life and conserving biodiversity remains the main driver behind the creation of marine protected areas.
A marine protected area is the one tool with which you can effectively conserve all levels of marine biodiversity from genes to species to the ecosystem, said Graham Edgar, a marine ecologist at the University of Tasmania, Australia. And there are no other tools for achieving that outcome as effectively.
But this goal has evolved. Marine protected areas are now widely seen as a tool to rebuild fish stocks and ensure sustainability of fisheries outside their boundaries. In fact, the U.N.’s Food and Agriculture Organization (FAO) defines a marine protected area as any marine geographical area that is afforded greater protection than the surrounding waters for biodiversity conservation or fisheries management purposes.
Intuitively, closing off areas to fishing to help the long-term recovery of fish stocks sounds simple enough. But not everyone is convinced.
Some critics counter that marine protected areas only really extend protection against one threat to oceans legal fishing from a long list: think global warming, acidification, oil spills, plastic pollution, agricultural waste, illegal fishing. Take Australia’s iconic Great Barrier Reef National Park, for example: Despite being considered one of the best-protected and most successful marine parks in the world, its coral reefs just suffered two years of severe bleaching and death due to warming waters.
Marine protected areas also don’t reduce fishing pressure, but simply move it to a different area, argued Ray Hilborn, a marine biologist and fisheries scientist at the University of Washington, U.S. Sure things get better inside the marine protected area, but you are fishing harder outside, he told Mongabay, adding that legal fishing can be regulated more effectively by other means.
Many scientists have also expressed concern over what marine protected areas mean to people who depend on fisheries for their living. As with terrestrial protected areas, conservationists and governments are now trying to understand how marine protected areas affect local people and find ways to either improve their lives or at least avoid harm.
Countries are now frenziedly creating more marine protected areas, increasingly very large ones, either out of genuine concern for marine life or to meet international targets. In the midst of it all, the efficacy of this conservation tool remains heavily debated. Is establishing marine parks better for species and habitats than leaving areas unprotected? Do marine parks improve fisheries and the well-being of fisheries-dependent communities? We read through some of the scientific literature and talked to experts to find out more.
There’s a mountain of research on marine protected areas. So we sampled a small portion of the literature, and shortlisted 42 peer-reviewed scientific studies: 39 were selected from the first 1,000 relevant hits on Google Scholar and three were added following consultation with experts. (Read more about our methodology and selection criteria here; you can access all 42 studies we reviewed here.) These studies look at several specific environmental, social and economic outcomes of marine protected areas, and evaluate whether those outcomes were better, the same as, or worse than for unprotected sites or for the same site before it was protected. Our review isn’t exhaustive and our search terms have focused specifically on certain outcomes, rather than on all the outcomes of marine protected areas that have been studied.
We also talked to seven marine experts to supplement our understanding of some of the broader trends and to fill in potential gaps.
The body of scientific literature on marine protected areas may be vast, but the quality of the studies within it is highly variable and riddled with information gaps.
One such gap, experts say, is that marine protected areas sometimes lack clear objectives when they are created. Was the marine protected area designed to protect a particular species? To improve fish catch in nearby fishing grounds? Or to attract tourists? Not all marine protected areas can or should be expected to meet all possible objectives, said Benjamin Halpern, a marine biologist at the University of California, Santa Barbara.
This lack of clear objectives can be problematic. Not only does it make the evaluation of a marine park’s effectiveness hard, but it also can lead to unrealistic expectations of potential benefits for biodiversity, fisheries or human welfare that aren’t always achieved, said Natalie Ban, a marine biologist at the University of Victoria, Canada.
Historical environmental and socioeconomic data from before marine protected areas were established is often unavailable, making it difficult to identify changes with certainty. Moreover, a large chunk of studies are snapshots that measure effects in a single season or year, or at a single location, making their results difficult to generalize.
The most critical gap with respect to ecological outcomes, in my opinion, is sufficient data over time to determine how, how quickly and for how long potential ecological effects are occurring, Halpern said. Most studies look at two or just a single point in time. Monitoring change over time provides much richer understanding of how ecosystems within and outside marine protected areas are responding, which in turn helps us understand why they are changing.
Many studies also do not compare marine protected areas with comparable control sites that is, unprotected areas of the ocean that are otherwise equivalent to the protected areas.
This lack of baseline data, long-time-scale information and good control sites can be a major roadblock to teasing out the effects of a marine protected area from other rival factors: Were the changes in fish populations caused by the creation of the marine protected area or by other ocean conditions, fishing pressure or the park’s location? Within our literature sample, for instance, only three studies accounted for multiple alternative explanations.
Not enough thought is given to the monitoring design when [a] marine park is being established, David Gill, a marine researcher at George Mason University and visiting scholar at the NGO Conservation International, told Mongabay. The gold standard would be to conduct surveys both inside the marine protected area before it is established and in comparable unprotected sites, and then continuously monitor both sets of conditions over time to see if the changes are just because of the marine protected area, or something else.
But achieving this gold standard is tricky, Gabby Ahmadia, a marine biologist with the World Wide Fund for Nature (WWF), told Mongabay.
Take the ongoing monitoring program at the Bird’s Head seascape in West Papua province, Indonesia. Ahmadia, whose team has been surveying a network of 12 multiple-use marine protected areas in the seascape, told Mongabay that selecting and then monitoring control sites is uncharted territory. Nobody had done this before, so it wasn’t something that I could look at in other marine protected areas, Ahmadia said.
You can use all your factors and environmental indicators and social criteria to say these would be good control areas, but you can only guess what’ll be underwater, she said. Sometimes you go underwater and you think no, this is not a good reef to survey. Or there have been some days when we were surveying sites and the reefs were dead. We spent two to three days searching for intact reefs but we couldn’t find any. It was definitely a learning experience. But we were able to get enough control sites that it did work.
However, there are a growing number of meta-analyses and systematic reviews; our sample included 10. These distill and explain some of the broader trends associated with marine protected areas.
By closing off areas of the ocean to fishing and other extractive activities, marine protected areas, especially marine reserves that ban all or most such activities, are expected to help species recover. A great deal of research has looked into whether they do, although much of it is not of the highest quality: many studies do not have rigorous designs and cannot definitively attribute observed changes to the marine protected area itself.
You just need a caveat that while some of what you’re seeing might be attributable to the marine protected areas, you can’t necessarily prove it beyond any doubt, said the University of Victoria’s Ban.
Of the 29 studies that looked at environmental outcomes within our sample, 19 were either case reports or simple inside-versus-outside comparisons that did not account for alternative explanations for the patterns they recorded. Only three studies considered a range of alternative factors and were more rigorous in their approach. The remaining seven were meta-analyses that looked at dozens of studies.
When considered together, though, most studies suggest that marine protected areas can be good for marine life.
In a meta-analysis published in 2003, for example, Halpern of UC Santa Barbara combined survey data from 89 studies and found that population densities, biomass, diversity and size of fish were generally considerably higher inside marine reserves than outside. He further analyzed a subset of 17 studies that had information from before the reserves were established, and concluded that fish density and biomass increased within one to three years of the creation of the reserves.
But the reserves affect different species in different ways, Halpern wrote. Slow-growing, long-lived species like cod tend to respond to protection more gradually than fast-growing, short-lived species like scallops. Similarly, heavily exploited species are likely to respond to protection more quickly than those that are not fished, because fishing the main activity impacting their survival is suddenly removed from the reserve.
In a more recent study published last year, George Mason University’s Gill and his colleagues compared fish data from 218 marine protected areas with matching unprotected areas to weed out potential rival explanations. The team found that, on average, fish biomass inside the protected areas was 1.6 times higher than in similar unprotected areas. We lost about a quarter of our dataset because we did not find appropriate protected and unprotected matches, but by doing this, we were also more confident about our results, Gill said.
Overall, researchers say that there is quite a lot of evidence to show that marine protected areas can benefit species, particularly those that have been threatened historically within the protected area boundaries.
2018 Copyright Conservation news