Tracking Marine Megafauna to Guide Ocean Conservation

Courtesy of Ana M.M. Sequeira

Some of the ocean’s most widely known creatures are also the most vulnerable to humans’ impact on the environment. Ranging from seabirds, sea turtles, and sharks to whales the length of commercial airplanes, these charismatic species—known as marine megafauna—are typically highly mobile top predators with critical roles in marine food webs. And they face growing threats from ship strikes, fishing and bycatch, pollution, coastal development, and climate change.

As development and use of the ocean intensifies, scientists are working to understand the extent to which human activities are affecting megafauna on a global scale. These efforts rely on a clear picture of where in the ocean megafauna live and travel—knowledge that has historically been both incomplete and elusive.

MegaMove, a project created by 2020 Pew marine fellow Ana M.M. Sequeira, seeks to fill in this picture by bringing together an international network of researchers to share data and improve understanding of marine megafauna movements, habitat use, and threats. Because of its potential to guide evidence-based conservation, MegaMove was recently endorsed by the United Nations as a project under the current Decade of Ocean Science for Sustainable Development. (Meet the 2022 Pew Marine Fellows—and see what they’re working on.)

This interview has been edited for length and clarity.

Why are marine megafauna so important to ocean ecosystems?

Marine megafauna have a key role to play in keeping the oceans healthy. For example, most are top predators, so they help keep ecosystems in balance by controlling populations of smaller predators and herbivores. They tend to perform long migrations, linking ecosystems that would otherwise never be connected. As they move through ecosystems, they transport nutrients from one area to another; their waste is an important fertilizer for phytoplankton—tiny marine plants and bacteria that absorb large amounts of carbon dioxide and form the base of marine food webs. When they die, megafauna can also serve as carbon sinks by transporting large amounts of organic material to the deep ocean, where it can be sequestered. Generally, they provide us with a good idea of whether an ecosystem is doing well, and it’s a good sign if they’re present. (Related: “Large Marine Protected Areas Can Benefit Migratory Species—But Design and Management Are Key.”)

What threats do they face?

Marine megafauna populations are affected by many of the human activities that are escalating in the ocean now: fishing, shipping routes, plastic and noise pollution, and climate change. And because this all happens in open ocean, including areas beyond national jurisdiction, the full extent of these effects is actually unknown.

Australian Institute of Marine Science

What drove you to create MegaMove?

These animals move thousands of miles—sometimes between entire ocean basins—but most studies on these species tend to be regional or local. But all these threats are happening at a global scale, and they are dynamic, meaning they change in space and time. The ocean itself is also a dynamic environment, and the animals are moving between locations. That led me to ask the question: How do these dynamic threats impact migratory animals that travel in a dynamic ocean? Answering these questions is what drove me to create MegaMove.

How does MegaMove work?

MegaMove brings the marine movement ecology community together. This is a community of researchers who study the movements of marine organisms, the drivers of movement patterns like migration and dispersal, and how movement patterns affect ocean ecosystems. We need to work together to gather information at a global scale and to address these global challenges. Our main aspiration is to create a unified perspective of what the solution might look like.

Why is tracking marine animals’ movements so critical to conservation efforts?

Marine megafauna spend most of their lives underwater, so it’s hard for us to understand what they’re doing and where they go. By meeting animals in a particular location and putting tracking devices on them, we can then let them go about their lives while we receive information about their movements. So tracking them means we learn more about how we can we protect them.

Tracking megafauna can also help us collect oceanographic information, such as ocean salinity and temperature, including in areas that are difficult for scientists to reach. This data is important to our understanding of the ocean.

How has your Pew marine fellowship affected your work?

Pew’s support came at just the right time, as I was starting to develop MegaMove. It provided the means to advance the project and the opportunity to further grow the engagement among marine researchers. It was a starting point that has led to different kinds of support for MegaMove, including from the U.N.

How will the U.N.’s Decade of Ocean Science for Sustainable Development intersect with your work on the project?

Getting an endorsement from the U.N. in the context of the Ocean Decade is absolutely fantastic. Not only does the endorsement draw attention to the questions we’re trying to answer with MegaMove—gaining a better understanding of what these animals are doing at a global scale, and the threats and impact of our own activities in the ocean—it also shows how important it is that the marine movement ecology community comes together to address these challenges. And then, of course, it’s a decade, so MegaMove has now become a 10-year project.

What do you hope MegaMove’s impact will be?

We ultimately want to overhaul marine megafauna conservation at a global scale. We need to think through the process of conserving these animals and how that works together with allowing the activities that we humans need for our own well-being. For example, maybe a slight change in a shipping route could bring benefits to some marine megafauna populations; perhaps changing fishing gear at a larger scale can address the problem of bycatch of nontarget species. (Video: What is bycatch?)

In the more immediate term, we’re focusing on engagement with the research community and on creating the first research outputs at a global scale addressing pressing conservation concerns. MegaMove serves as a forum for the marine movement ecology community to come together and address those concerns. I think that’s the first step; then, together, our community can work to translate our results and better inform ocean management at a global scale.

This article was previously published on pewtrusts.org and appears in this issue of Trust Magazine.