Overpopulation Overpowers Ocean

Published on May 17th, 2017

Two-thirds of once-vast sea now stressed by exponentially increasing human activity

National Geographic
April 2017 magazine cover

“The Next Human” …
and the “Next Ocean” as well?

The April 2017 issue of National Geographic magazine reports that scientists were stunned recently to learn that fully two-thirds of the ocean – once regarded as vast and virtually indestructible – is showing unmistakable signs of manmade stresses and strains.

Lead researcher Ben Halpern, of the Marine Science Institute at the University of California, Santa Barbara, told National Geographic that a “booming population is chiefly to blame.”

At any given moment, all we can ever see of the ocean with our eyes alone is its evanescent, shimmering surface: seemingly ever-changing and moody – “frowning and angry” when it is dark, green, gray and wave-tossed; “smiling” when it is placid and blue – but essentially the same today as it was a century or a millennium ago.

Yet appearances can deceive.

These superficial oceanic mood swings amidst seeming constancy through the eons are misleading, masking long-term changes in the essence and health of the ocean, the waters that comprise it, the temperature and chemistry of those waters, and the myriad and magical creatures that make the sea their home.

Halpern and his team generated what amounts to an “x-ray” of the ocean using satellite images and modelling software. With these they developed a revealing portrait of the hidden sea and its depths, one that depicts the extensive effects of widespread human activity.

In the map shown of the Pacific Ocean and Indian Ocean, the darker areas indicate where the ocean is suffering the greatest adverse impacts from human activity. The darker the area, the more stressed waters and marine life are from overfishing, large amounts of shipping, the disruptive effects of climate change and/or all three forces.

Oceans under stress from human activity: the darker the area,
the greater the negative influence of human stressors.

Most of the darkest zones on the map are found in the Northern Hemisphere, not surprisingly where human population is most concentrated. Almost 90 percent of the global population resides in the Northern Hemisphere, and much of it on or near the coasts.

However, the resources consumed and the wastes and pollutants generated by 7.5 billion human beings have ill effects that aren’t confined just to parts of the ocean in close proximity to cities and populous coastlines. For example, many of the world’s industrialized, commercial fisheries occur far, far away from population centers.

Large swells and whitecaps roil the surface of the remote Bering Sea,
north of Alaska’s Aleutians Islands, whose snowy peaks and
ice-crusted crests jut skyward from the frigid waters.

Years ago I worked as a fishery biologist for the National Marine Fisheries Service, helping in the management, conservation and regulation of the Bering Sea bottomfish fishery, for walleye pollock and Pacific cod. At the time, measured in terms of annual catch by aggregate weight, the fishery for the pollock was the single largest commercial marine fishery in the world.

The goal of virtually all fisheries is “maximum sustained yield,” that is, the largest yield or catch that can be taken from the stock of a species sustainably, in perpetuity. It is a worthy ideal, but one that is often extremely difficult to achieve in practice for a variety of reasons.

The Bering Sea, in spite of its forbidding,
desolate appearance and isolation,
supports one of the world’s greatest
commercial fisheries.

The Bering Sea fishery is set in a frigid, extremely remote, far-flung corner of the world, virtually devoid of human settlement; it is almost literally located at “the ends of the earth.” Yet this isolation does not shield it from the ravenous demands of billions of human consumers elsewhere in the world.

Author Kolankiewicz lifts a 60-lb. Pacific halibut from a pile of fish
hauled up from the bottom of the Bering Sea by trawl nets dragged
along the bottom of the ocean. This impressive fish was part of
the enormous, wasteful bycatch, and never brought to market.

The pollock fishery I worked to help manage years ago furnished millions of pounds of frozen fish annually to the gigantic Asian market.

Over the decades, this bottom trawl fishery has struggled to maintain yields of targeted species, and has had a huge adverse impact on the ecology of the Bering Sea, affecting benthic (bottom) habitat, marine food chains, non-target finfish and shellfish species (bycatch or incidental catch of unwanted species), seabirds and marine mammals.

Halpern told National Geographic: “A lot of the ocean is getting worse, and climate change in particular is driving a lot of those changes.” As with overfishing, the marine effects of a warming climate are occurring globally, often thousands of miles from the populations whose consumption of fossil fuels (coal, oil, natural gas) and deforestation are increasing the atmospheric concentration of carbon dioxide and other greenhouse gases.

The adverse effects include rising water temperatures, which cause bleaching and mortality of coral reefs in the tropics, and increasing acidity, as carbon dioxide dissolves in the upper layers of the ocean, dropping its pH, making it more acidic. Acidified waters make it more difficult for shellfish to construct and maintain shells from calcium carbonate.

In 2008 and 2013, Halpern’s team of researchers used imagery and modeling to develop a comprehensive view of an ocean “in transition.” They found that more than 75 percent of coastal waters in particular are being damaged by climate change and increases in the effects of harmful land-based activities, including pollutants.

What is at risk: tropical coral reefs are often compared to tropical rainforests
for their beauty and biodiversity. They are at risk from overfishing,
rising ocean temperatures, bleaching, pollution, dynamite,
sedimentation and ocean acidification.

All in all, the marine scientists categorized more than 40 percent of the ocean as “heavily impacted” by human activity. People once considered the ocean so colossal that we could abuse it with impunity. Our insults were no more consequential than a flea on an elephant. No more.

National Geographic reports that not all the news is gloomy: in some areas human impacts have been lessened. In parts of the North Atlantic, more fuel-efficient ships and new regulations have reduced damage. In 2016, countries around the world designated more than 40 new sites as marine-protected areas, safeguarding more than 1.4 million additional square miles from commercial fishing, energy drilling and other potentially harmful activities.

If the oceans succumb to human folly and excess, so will we humans ourselves.


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