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Conserving ocean life: three ways to improve U.S. marine protected areas By Heather Welch

Title Image: Life beneath the kelp forest. La Jolla Cove, San Diego. Corinne Klein/Chambers Group Inc, used with permission.

Our oceans support an incredible diversity of marine life, from microscopic organisms such as plankton to megafauna such as blue whales. But threats like climate change, fishing and offshore oil and gas development are stressing marine life and degrading ocean health. To help protect marine life, the United States has a network of over 1,600 marine protected areas (MPAs) that cover 81% of its national waters.

While these figures may sound impressive, they are ultimately misleading and oversell U.S marine protection.

A map of the network of the US marine protected areas.
Map 1. The U.S. marine protected area network. Courtesy of the author.

 Marine Protected Areas are portions of the ocean where human activities are regulated. They are important tools for protecting marine biodiversity, but like any tool, they must be used correctly to achieve their purpose. The purpose of MPAs is to prevent loss of marine life. Some ocean conservation advocates assume that creating MPAs automatically prevents biodiversity loss, or that coverage equals protection. By this logic, more MPAs equates to more protection.

A growing body of research suggests that coverage does not necessarily equal protection. Furthermore, poorly-designed protected areas, whether on land or sea, can actually have negative effects by exhausting limited conservation resources and support, making it harder to establish future protected areas.

If coverage equaled protection, then our extensive network would have great potential to prevent loss of marine life.  As it exists, the network has three key weaknesses that reduce its potential.  Fortunately, there are concrete solutions to make this powerful tool more effective.

Not all protected areas are created equal

The wide range of goals and management bodies makes it difficult to assess how much protection marine life really has within U.S. waters. The U.S. MPA network was created to address an array of goals, such as managing fisheries and preserving cultural heritage sites. The network is managed through collaborations between federal, state and local governments, and nongovernment partners.

Some protected areas are more protected than others. The strictest MPAs do not even allow humans to enter; in contrast, the most lenient limit actions that affect one commercial species without restricting other activities. Fishing – arguably the greatest direct human threat to marine biodiversity – is allowed in over 71 percent of the waters covered by U.S. MPAs, for example in most near-shore waters.

Map of US MPA's separated by areas that allow commercial fishing and those that do not.
Map 2. U.S. MPAs divided into two groups: MPAs that allow some form of commercial fishing and MPAs that prohibit commercial fishing. Courtesy of the author.

Standardizing U.S. MPA types would make them easier to evaluate. The International Union for Conservation of Nature (IUCN) developed a system for categorizing protected areas based on their level of protection. Many international bodies such as the United Nations, Australia and New Zealand use this system. If we adopted the IUCN categories, the status of U.S. marine protection would become more transparent, allowing for straightforward national and international evaluations and comparisons.

Adopting the IUCN categories would cause many current MPAs to be decommissioned, because the U.S. system allows waters regulated solely for fisheries management to be considered MPAs and the IUCN system does not. To get an idea of how many U.S. MPAs would remain, take a look at the official (albeit slightly outdated) MPA map created by the IUCN. But this would be a positive step, since it would free up conservation resources, such as money and personnel, which could be used to create new, strictly managed MPAs.

Our strictest MPAs aren’t where we need them

MPAs can’t prevent biodiversity loss unless biodiversity is threatened, and our strictest MPAs are concentrated in areas where threats to marine life are relatively low.

No-take areas are the strictest type of MPA. These are the national parks of the sea, preventing all types of extractive operations such as fishing and offshore development. No-take areas have the greatest potential to prevent loss of marine life, but only if they are located in areas where they can reduce threats.

Because no-take areas prevent resource extraction, there are economic incentives to place them in waters with limited resources, also known as low-cost waters because they have low economic value. The majority of U.S. no-take areas are concentrated over deep, remote waters in the central Pacific that are unsuitable for many extractive industries and therefore less threatened. While it is important to protect the open ocean, near-shore waters, where human threats are more prevalent, also need protection.

Map of US MPA's showing that most no-take areas are in the North Pacific
Map 3. U.S. no-take areas are concentrated in the central Pacific. Courtesy of the author.

To prevent biodiversity loss, no-take areas must be explicitly designed to reduce threats. One way to do this is to map suitability for a given threat.

For example, development suitability might be mapped as a function of distance from shore and depth. Then quantitative objectives could be set for how much area to protect from each threat. For instance, a no-take could be designed to protect 30% of area that is suitable for development.

Protection is biased to the tropics

No-take areas only cover a few types of habitat, leaving other habitats vulnerable.

U.S. national waters contain many different types of unique habitats, from the reef communities found in the Hawaiian Islands to Alaska’s polar food web. The U.S. Government recognizes 19 marine habitats. A primary goal of conservation planning is to protect samples of each habitat type. This approach ensures that no habitat is left completely vulnerable.

The World Parks Congress recommends protecting 30% of each habitat’s area within no-takes. Two of the U.S. habitats in the central Pacific have extensive no-take area coverage, but 16 other habitats have one percent or less of their areas protected by no-takes. One habitat near Florida has four percent coverage.

Map of US MPA's showing that many ecoregions have limited or no no-take areas
Map 4. Many U.S. ecoregions have limited no-take area coverage.


To protect a wider sample of its ocean life, the United States should include portions of each habitat no-take areas. These habitats often extend over hundreds of thousands of square kilometers and contain many unique sub-habitats.

For example, kelp forests and the biodiversity they support are only found in shallow waters within U.S. west coast habitats. Protecting these sub-habitats will require mapping fine-scale habitats on the order of tens of square kilometers, such as this one. Planners should then follow the World Parks Congress’ recommendation and protect 30 percent of each sub-habitat within no-take areas. These no-takes should be complimented by other types of MPAs and management arrangements.

MPAs can be powerful tools for protecting marine life, but only if they are systematically designed and managed. The take home point: the number and size of MPAs doesn’t tell us anything about a network’s ability to prevent biodiversity loss. Asking the hard questions – like how strict are the MPAs, where are the strict MPAs located relative to threats, and how are strict MPAs distributed across habitats – can help get us closer to an honest appraisal. Coverage doesn’t necessarily equal protection – but when MPAs are designed to make a difference, it can.



Heather WelchHeather Welch is a geographer of dynamic natural resources. She studies how large-scale patterns – for example marine currents, charismatic megafauna, or weather – evolve over space and time. She is currently exploring how climate change will alter the distributions of marine species, and what we can do to plan for it. You can catch up with her work at her page on The Conservation Planning Group. 


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