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Reflections from Marine Ecologist Ben Halpern

In Search of the Last Pristine Places in Our Ocean

By Ben Halpern

ben halpern head shotSeveral friends and I were sitting around eating lunch in Okinawa, Japan, feeling a little depressed after hearing talk after talk at the 2004 International Coral Reef Symposium about the dire condition of reefs around the world. We had just been told that many reefs had already disappeared and few areas unaltered by humans remain on the planet. As we sat there gloomily spearing our sushi with our chopsticks, one of us proposed an idea that would end up consuming our lives for the next few years: We have to find a way to see the last pristine places in the ocean before they disappear.

Oil Platform SeaWeb Ocean Voice

Drilling for oil disturbs seafloor habitats.
Photo: © Wolcott Henry 2005

Rather than embarking on a round-the-world tour of popular diving spots to better understand the full extent of human impact on the ocean, we got to work collecting information about where the many activities detrimental to marine environments were occurring. We would overlay these activities—such as commercial shipping, climate change, land-based runoff, invasive species, oil and gas drilling, and commercial fishing—onto a map to see how the world would look. Where no activities were occurring should be some of the most pristine locations.

Three-and-a-half-years later, after piecing together funding from various sources, assembling a team of remarkably dedicated researchers, building a network of collaborators eager to help make the project a reality, amassing enormous amounts of data and putting in a lot of long days, we were ready to produce the global map of human impacts on the oceans. When our computers finished cranking through terabytes of data, I sat with baited breath to get the first glimpse at the map.

We knew the big picture would show a lot of impacted areas, but what we saw was shocking: No truly pristine place remains. Human activities heavily affect more than 40 percent of the world’s ocean—not a single square mile remains untouched. Indeed, only a little more than three percent of the oceans are lightly impacted, and much of this area is under sea ice in the poles, where people rarely go.

Global Map of Remaining Pristine Places SeaWeb Ocean Voice

Although some have less impact than others, human actions such as commercial fishing and increased use of fossil fuels leading to global climate change have impacted every area of the ocean.
Credit: B. Halpern

See Full Version of the Global Map of Human Impacts on Marine Ecosystems >>

Purse-seine fishing boat SeaWeb Ocean Voice

Purse-seine nets (above) can take large amounts of fish at once, including many untargeted species as bycatch hauled in from a commercial fishing vessel (left).
Photo: © Wolcott Henry 2005

Some of the hotspots of human activity in the ocean are not too surprising—the North Sea, the East and South China Seas and Japanese waters, the Mediterranean and the U.S. East Coast. People have used these areas intensely for centuries and they have huge human populations nearby. But other hotspots were a bit more surprising—the eastern Caribbean, the Bering Sea, the Persian Gulf and the waters off of Sri Lanka and Singapore. The most heavily affected ecosystems worldwide included coral and rocky reefs, seagrass beds and mangroves.

Bycatch from Trawler SeaWeb Ocean Voice
Photo: Elliott Norse, MCBI

We also found that climate change, commercial fishing and shipping are having the largest impact globally, while in coastal waters essentially every activity we looked at was having a significant impact on marine ecosystems. Obviously these results average important small-scale differences in how these activities are managed–such as some local fisheries are sustainable–but they provide guidelines for regional to global-scale management needs.

Although initially daunting, these results allow us to make reasonable comparisons among the ecological conditions of locations throughout the world. We can better estimate the relative effectiveness of different types of mitigation activities, such as marine protected areas that limit fishing, land-use regulations that reduce pollution runoff or climate treaties that limit fossil fuel emissions. In particular, the layers of our analyses allow for a better understanding of how to implement comprehensive ocean conservation strategies through approaches such as ecosystem-based management.

Coastal Development and Agriculture SeaWeb Ocean Voice
Land-based runoff from agriculture and cities on or near coastlines has been detrimental to marine ecosystems
Photo: © Wolcott Henry 2005

In other words, we can now look at an area of the planet, assess which human activities are having the greatest ecological impact at that location and then focus our management—and potentially restoration efforts—on those key drivers. For example, in the Bering Sea, commercial fishing and climate change are currently having the greatest impact. Consequently, efforts to reduce the impact of commercial fishing through altering fisheries management in this region and reducing fossil fuel emissions should significantly improve the health of this area of the ocean.

reef scape SeaWeb Ocean Voice

While those areas that human actions have not severely impacted may be shrinking, knowing where we affect these marine ecosystems the most can guide efforts to conserve our ocean.
Photo: Chuck Savall

My colleagues and I are still planning on seeing the last of the most pristine places in the oceans. But we embark on our trip now knowing where these places are most likely located, and we now know to temper our expectations about finding any place that is truly pristine. If we continue to work to maintain effective fisheries management, improve insufficient fisheries policies, better regulate land uses that dump pollution into the ocean and reduce greenhouse gas emissions, we have hope of having a relatively healthy ocean.

Ben Halpern is a marine ecologist at the National Center for Ecological Analysis and Synthesis in Santa Barbara, Calif. He researches how ecological communities differ from one another and how such information can be used to improve conservation and resource management.


See more maps below detailing human impacts on the ocean.

Map of Global Shipping Impacts
Shipping Traffic

Map of Global Sea Surface Temperature Anomaly
Sea Surface Temperature

Map of Global Trawl Fishing Impacts
Commercial Fishing
This map shows the frequency of shipping traffic along shipping routes around the world, ranging from low (blue) to high (red).
Sea surface temperature has increased since the mid-1980s. The orange areas indicate where temperatures averaged above normal for the past two decades.
Commercial fishing destroys seafloor habitat all over the world. The red indicates where the most fish have been caught.

Credit: B. Halpern
This study by Ben Halpern and his colleagues appears in the February 15th, 2008, issue of Science.

View and download these ocean conservation photos at SeaWeb's Marine Photobank >>