Skip to content Skip to navigation

Q&A: Making the Case for Mobile Marine Protected Areas

January 20, 2020

In 2000, Stanford marine ecologist Larry Crowder read an intriguing scientific paper that introduced the concept of mobile marine protected areas, or mMPAs – ocean sanctuaries whose boundaries can shift in space and time to protect animals that follow changing ocean features like the Gulf Stream. When the features moved, the protections moved with them.

"I remember thinking, ‘It’s a cool idea, but we can’t do it,’” said Crowder, the Edward Ricketts Provostial Professor in Stanford’s School of Humanities and Sciences and a senior fellow at the Stanford Woods Institute for the Environment.

Fast forward twenty years. The technological hurdles that once gave Crowder pause about the feasibility of mMPAs have largely been overcome. Remote sensing satellites can now track boats and fishing vessels anywhere on Earth in real time. GPS allows fishers to know instantly whether they’ve strayed into a protected area, even if the boundaries have changed. And scientists can remotely follow the movements of sharks, turtles, whales and other creatures and then use computer models to predict their future movements.

But even though mMPAs are now technologically possible, the legal and policy frameworks necessary to make them a reality are still lacking. “It’s time to get the policymakers involved in thinking through how they might use this new tool,” Crowder said.

To this end, Crowder and his colleagues have published a commentary in the journal Science proposing that mMPAs and other “dynamic area-based management tools” be discussed at the June 2–6 meeting of the United Nations Convention on the Law of the Sea (UNCLOS) in Lisbon. The convention, a treaty which has been in effect since 1982, defines the rights and responsibilities of nations with respect to their use of the world's oceans and establishes guidelines for the management of marine natural resources.

The Center for Ocean Solutions spoke with Crowder about how mMPAs can reduce conflicts between humans and marine life and help protect species and habitats under climate change. The following interview has been edited for clarity.

First, what is a mobile marine protected area?

Marine protected areas evolved out of the use of terrestrial protected areas to protect locations with high amounts of biological diversity, unique habitats or cultural sites. On land, static designations make sense, since terrestrial habitats don't move around in ecological time.

In the sea, however, there are some habitats that sit still for the most part – like coral reefs, kelp forests and seamounts – but there are other habitats that move around, including the positions of ocean fronts and currents.

It seems like an abstract idea, but we do it all the time already. Think about air traffic control. Here in the Bay Area, we have three major international airports. Planes can land from the north or from the south. When it gets foggy, air traffic controllers space out the airplanes, and when the wind direction changes they might have planes land from the north rather than from the south. All of those conditions are thought through based on changing environmental conditions. There's a protocol that says when the visibility drops below some level, you space out the airplanes. There's no public meeting or discussion. It just happens because the rules have already been worked out in advance.

What is an example of an ocean feature that moves around?

The North Pacific Transition Zone is a ribbon of water that’s defined by certain bands of water temperature and density. It shifts 1,000 kilometers (about 621 miles) north to south with summer and winter. It’s like a buffet line that many animals flock to in the North Pacific because most of the ocean doesn't have high densities of food, but this convergence zone does. It’s also where conflicts between humans and marine life are likely to occur. The question is, by using a dynamic approach, can we reduce the conflicts by just shifting where humans operate a bit from where they operate now?

If I say, "Draw a rectangle around the entire North Pacific Transition Zone in its summer and winter locations," you end up with a big box because it’s 1,000 kilometers north to south. But another option is to draw a smaller polygon that covers it as it moves from summer to winter. If you use mobile marine protected areas rather than static areas, you can potentially protect a much smaller box.

What kinds of marine animals would mMPAs protect?

Any organism that you think of as being an open ocean organism that doesn't swim willy nilly across the ocean. There are places in the ocean that they go to. To give one example, endangered loggerhead sea turtles nest in Japan but they range across the entire Pacific Ocean. The juveniles feed in Baja California, Mexico, and then they return to Japan some 20 to 30 years later when they are ready to breed. The turtles don't move haphazardly. They move in response to these oceanographic features. There's a predictable habitat where they end up in the North Pacific Transition Zone. That habitat moves seasonally and will shift farther with climate change. Other examples include albatrosses, whales, sharks, tunas and so on.

What would an mMPA that protects sea turtles look like?

In fact, there's already a program in place that NOAA (National Oceanic and Atmospheric Administration) put together that's called Turtle Watch. By putting satellite tags on loggerhead and leatherback sea turtles in the North Pacific, NOAA scientists have developed statistical models that allow them to determine habitat associations of those turtles over time. They update their forecast once a week.

It turns out temperature is a really strong predictor of where the turtles will be. So they can create models that basically say, "If you fish at this particular temperature, that's likely to be where the sea turtles are. So fish north of there, or fish south of there, but don't fish in this band."

Right now, Turtle Watch is only enforced in the United States. But you could imagine something like it serving as an advisory to the international fleet as well, to tell them, "Go catch tunas, go catch swordfish, but catch them in a place where your turtle bycatch is likely to be low."

Can you summarize your proposal about mMPAs to the United Nations?

We're not proposing that UNCLOS be changed. We’re recommending a follow on treaty which would allow new, more modern approaches to area based ocean management. What we argue in our paper is that we're now in a position scientifically to consider marine protected areas whose boundaries can shift. It ought to at least be on the table.

The proposals are for the delegates who are negotiating this potential new treaty to just add the idea of mobile protected areas to their venue, or at least not exclude it. It hasn't been on their radar because it's a relatively new thing. Whether they actually use it and when and where is totally up to the people who are working these cases.

How do mMPAs tie in or overlap with your own research?

I've been working on bycatch in fisheries for 30 years. I study how to keep turtles out of fishing nets and sea birds out of longlines. In the past, scientists have focused on “gear fixes.” They might, for instance, try to change the longline hook or use different baits or experiment with putting a different-colored light stick on the longlines. I worked on turtle-exclusion devices that allowed turtles that get into a trawl to get kicked out before they drown.

Dynamic management offers another way to reduce risk to marine animals by separating in space and time the critters that you’re trying to protect from the human activities.

Any environmental management that you implement has to work for the people and the planet. We want to come up with solutions that achieve protection for the sea birds and sea turtles but also allow fishermen to continue to do business. We want to sufficiently protect whales but also allow global shipping to continue.


To read all stories about Stanford science, subscribe to the biweekly Stanford Science Digest.

Contact Information

Nicole Kravec
Communications Manager