Rewilding the ocean

As the global push to create Marine Protected Areas (MPAs) gathers pace, driven by the 30x30 campaign to protect 30% of the planet’s wild lands and waters by 2030, so too have the misgivings being voiced in various parts of the conservation community about just how effective MPAs really are. Vox senior environmental reporter Benji Jones recently summarized some of these concerns in a dispiritingly titled article “America’s best idea to protect its oceans has one big problem: It’s not working.” 

Jones’s article shines a light on some important issues surrounding the current state of MPAs – the main one being that a lot of them aren’t actually protected at all. While on paper, almost half of America’s ocean is covered by some form of protection, in reality, only around 3% of the total U.S. MPA area is completely off limits to human interference, leaving the vast majority vulnerable to exploitation – including hugely destructive fishing practices that have in some cases led to immense damage to ecosystems within their borders.

The specific criticisms Jones raises in his article are not wrong. But the headline is, at best, misleading. As real-world experience of MPAs grows, it’s becoming abundantly clear that fully protected “no-take” MPAs – those in which all extractive and destructive activities are banned – are actually highly effective in preserving biodiversity, strengthening the resilience of marine ecosystems and helping to restore wildlife habitats and populations.

Take, for example, California’s MPAs. Within a decade of the establishment of a network of fully protected zones in the Channel Islands National Marine Sanctuary, studies were indicating that the density of targeted (i.e., fished) fish species had increased inside the protected zones by 50% and their biomass by 80% in the first five years of the reserves’ existence. The biomass of predators inside the reserves was “significantly greater” than in unprotected areas, with 1.8 times more piscivores and 1.3 times more carnivores in these zones. Subsequent research has found that the average size and abundance of certain species was “significantly larger” in the protected areas, and noted increases in the biomass of certain species occurring much faster inside the reserves than in surrounding areas.

Or take Cabo Pulmo in Mexico – a 27-square-mile no-take MPA between Pulmo Point and Los Frailes Cape, created in the late 1990s. A 2011 study revealed that within just 10 years of the implementation of protections, overall biomass in the MPA had increased by 463%, bringing the area’s coral reef, previously stripped almost completely barren due to overfishing, to a level comparable to unfished reefs. Fish size had also increased, and the biomass of top predators like sharks and grouper had grown by 1,070%. The combination of higher densities and larger fish created an average biomass more than five times that of nearby unprotected areas.

These aren’t anomalies. The more we get to know about MPAs, the clearer it becomes that fully-protected areas consistently help to support larger, healthier and more diverse populations of ocean species and help protect the balance and integrity of marine ecosystems, both within their boundaries and in the surrounding area.

A 2009 analysis synthesizing a range of studies of fully protected MPAs around the world showed that these protections result in significant increases in biomass, the size and density of organisms and the number of species present – all key metrics used to assess the health of the ocean. In half of the MPAs studied, total biomass of studied species was more than triple that of unprotected areas, and density more than 60% higher. A study of the Governor Island reserve in Australia found that the biomass of rock lobsters was a whopping 2,300% higher in the protected area than outside it, and in the Las Cruces Reserve in Chile, the population of the species being monitored were on average 2,210% higher inside the MPA than outside it.

Other research presents similarly eye-catching figures. One 2017 study, for example, found that average biomass of fish in fully protected MPAs was 670% greater than in nearby unprotected areas and 343% greater than in partially protected MPAs. Interestingly, that study also found that fish biomass was restored in fully protected marine reserves over time after the implementation of protections, whereas in partially protected MPAs it was not.

MPAs have also been found to protect and enhance biodiversity within their borders. A 2006 meta-analysis of data from 44 fully protected MPAs showed that levels of biodiversity in these areas increased by an average of 23%, and fish numbers in surrounding areas also significantly increased as a result of spillover from the protected zones.

Increased biodiversity in turn increases degraded ecosystems’ ability to recover from degradation. For example, within two decades of its designation, a fully protected area in New Zealand’s Leigh Marine Reserve recovered from destruction of kelp forests triggered by the unchecked growth of its sea urchin population, which thrived in the absence of heavily-fished predator species. Restrictions on fishing allowed for a rise in predator populations, including sea urchin-eating fish, resulting in the revival of the area’s kelp forest and a return of the local ecosystem to a complex, healthy condition.

The list of studies is long and growing, but the point is this:

The patchy record of MPAs in U.S. waters doesn’t point to inherent problems with the MPA concept. It just shows we’re doing it wrong.

The 30x30 target is a decent enough target to aim for, but randomly cordoning off 30% of the ocean and claiming you’ve met your conservation goals isn’t going to have any real impact. For that to happen, a number of other conditions have to be met.

Firstly, ‘protection’ has to mean ‘full protection.’ Not fisheries management areas. Not flimsy regulations that include exceptions for certain kinds of fishing or mere prohibitions on certain types of fishing gear or shipping. Full protections, with all extractive activities off limits.

Second, the protected area must include 30% (at least) of every geographic and ecological region – not just one massive chunk of ocean in the western Pacific. Given the lack of fully protected MPAs in U.S. waters outside of the remote Pacific, the immediate priority should be ensuring that full protections are put in place across all key regions to preserve the diverse habitats and ecosystems in the country’s waters. Right now, special attention should be given to near-shore areas, currently significantly underrepresented in the U.S. MPA inventory.

By the same token, creating small, isolated MPAs is not, in itself, enough to have a major impact. MPAs should be as large as possible (when it comes to marine protections, science shows that size does matter), and should be ecologically linked in regional networks to ensure connectivity between habitats. Research shows that well-connected, ecologically coherent MPA networks can help highly mobile marine animals like whales and sea turtles by protecting important sites along their migratory routes, such as feeding and breeding grounds. (In the western Pacific, for example, protection of the nesting beaches and foraging habitats of green turtles, and portions of their routes to foraging grounds outside the protected zone, has played a role in rescuing these animals from the brink of extinction.)

Lastly, planning, designing and implementing MPAs and MPA networks needs to be based in a comprehensive, strategic, science-based process that integrates regional scientific knowledge and engages local communities and other stakeholders, coupled with a robust strategy for how these protections are going to be monitored and enforced once they’ve been implemented – as happened in California, whose progress toward successful marine protected areas is now widely considered a valuable case study in how to plan, implement and manage a statewide network of MPAs.)

With the health of the world’s ocean hanging in the balance, the need for action to boost the ocean’s resilience against the myriad threats it currently faces has never been greater. Combating those threats will require action on a range of different fronts simultaneously – one of which is the establishment of marine protected areas. Get it right, and they work.