How to measure the ocean

Humans have always looked to the ocean. Immensely vast, covering 71% of the earth’s surface, is has always been an important source of food and wealth, as well as sea transportation and trade routes. Access to the ocean has historically been a decisive strategic factor for countries and empires. It still remains poorly understood, and new and bizarre species of fish still being discovered (or rediscovered in the case of the coelacanth), and the bottom has barely been mapped. It’s volume is a staggering 1.37 billion cubic kilometers, which undoubtedly contain many more unknown animals.

However, as we’re learning to measure the ocean, we’re learning how dangerously unbalanced it has become as a result of human activity, both directly and indirectly.

A recent article in The Economist describes how the sea is becoming increasingly acidic. The oceans, like forests, function as what is known as “carbon sinks”, absorbing the ever-increasing amount of carbon emitted by humans. This reduction of carbon in the atmosphere is incredibly important, and is often relied-upon in calculating the amount of CO2 that humans can emit, and is factored in when calculating the reductions in emissions necessary to mitigate global warming. However, as the article lays out, when CO2 is absorbed by the ocean, it forms carbonic acid. As more and more carbon dioxide is absorbed by the ocean, more carbonic acid is produced, slowly tilting the oceans pH from alkaline towards acid. This trend is a potentially major disruption to marine life.

“[C]alculations suggest that if today’s trends continue, the alkalinity of the ocean will have fallen by half a pH unit by 2100. That would make some places, such as the Southern Ocean, uninhabitable for corals. Since corals provide habitat and food sources for many other denizens of the deep, this could have a profound effect on the marine food web. ” The research of Dr. Hoffman, a marine biologist at UC Santa Barbara, implies that the combination of heat and a decline in alkalinity is more deadly to marine life than either alone.

This is particularly worrying news, as many oceanic ecosystems, particularly those relied on by humans for food, are already in collapse. There have been many newspaper articles and troubling reports over the years that many fisheries are severely depleted. However, the vastness of the ocean makes the scope of the problem that represents is difficult to understand.

This map, from a recent Scientific American article, makes the profound effect of human activity on the oceans very clear.


(The Torres Straight is the channel between Australia and Papua New Guinea.)

This map, part of an article in the February 15 issue of Science, was created by a team of international scientists, led by marine ecologist Ben Halpern of UC Santa Barbara. They developed maps of the 17 different ways humans affect the ocean, including “fishing, fertilizer runoff, pollution, shipping and climate change.” They then overlaid those individual maps to form a broad picture of the human impact on the ocean.

As you can see, there is essentially no area of the ocean unaffected by humans, and the majority of the ocean, and nearly every coastline, has suffered at least “medium-high impact.” Things look particularly bad in the North Sea, along the coast of Norway, the Sea of Japan, the Gulf of Thailand, and off the coast of Sri Lanka. Things look slightly less dire but still bad off the coasts of along the coasts of New England and eastern Canada and the Caribbean.

The prognosis is poor. According to a November 2006 article in Scientific American, global fish production may have peaked in 1994. Many traditional fisheries, such as the cod areas off of New England and the North Sea, are nearly totally gone. However, world demand for fish continues to rise, led by Europe, which imports approximately 60% of its fish consumption, approximately $20.6 billion annually.

While the environmental impact of collapsed fisheries is still being determined, the social costs are increasingly clear, as was recently outlined in several New York Times articles. Overfishing in Europe has led fishing fleets to the waters of Northwest Africa, where fishing stocks have been rapidly declining. The emptying seas have intensified the economic pressures on local residents, many of whom are or were fisherman, to emigrate, often illegally. (article)

As another New York Times article puts it, “Fish is now the most traded animal commodity on the planet, with about 100 million tons of wild and farmed fish sold each year. Europe has suddenly become the world’s largest market for fish, worth more than 14 billion euros, or about $20.6 billion a year. Europe’s appetite has grown as its native fish stocks have shrunk so that Europe now needs to import 60 percent of fish sold in the region, according to the European Union. … In Europe, the imbalance between supply and demand has led to a thriving illegal trade. Some 50 percent of the fish sold in the European Union originates in developing nations, and much of it is laundered like contraband, caught and shipped illegally beyond the limits of government quotas or treaties.”

Through these articles, one can see network of various consequences arising from the abuse and depletion of the ocean’s resources. The overfishing of larger species leads to increased pressure on smaller species, as global fish stocks continue to collapse. Fewer fish means higher prices, and more competition for the remaining fish, a competition in which big industrial fishing fleets and illegal fishing have an advantage over legal and small-scale operations. An editorial in the New York Times succinctly sums up the main issues.

Among all the dismal news, there are a few bright spots. Chefs in recent years have become much more aware of their their produce and meats are sourced from, and local food sourcing has spread far beyond Alice Waters and Chez Panisse. In London, restaurateur Tom Aikens is opening a sustainable fish and chip shop, using less-threatened pollack, gunard, rays and sole in addition to sustainably-fished cod. Chef Barton Seaver is serving only sustainably-fished species and educating his customers about sustainable dining at his Washington D.C. restaurant, Hook.

However, it seems that the only way to salvage the world’s fisheries is simple: stop eating so much fish. When you do eat fish, eat low on the food chain, picking clams over shark. Eat sustainably fished species, like Alaskan wild salmon, instead of red snapper. And eat local. The fish will be fresher, tastier, and you’ll have more information about where it came from. Fixing the fisheries will be hard to do, especially as global fish consumption has been rising every year. But it doesn’t look like we have many other options. If we do nothing, global fish stocks will quickly plummet below the level at which they could replenish themselves. Aquaculture holds a lot of promise, but there are still associated problems with pollution, fertilizer run-off, and disease in the farmed fish.

We can also follow the advice Taras Grescoe, author of Bottom Feeder: How to Eat Ethically in a World of Vanishing Seafood, gives in a recent New York Times op-ed: eat the invasive species which have moved into the Great Lakes, Chesapeake Bay. We get fed, the local species get a helping hand, and everybody goes home happy.

Benjamin S. Halpern, Shaun Walbridge, Kimberly A. Selkoe, Carrie V. Kappel, Fiorenza Micheli, Caterina D’Agrosa, John F. Bruno, Kenneth S. Casey, Colin Ebert, Helen E. Fox, Rod Fujita, Dennis Heinemann, Hunter S. Lenihan, Elizabeth M. P. Madin, Matthew T. Perry, Elizabeth R. Selig, Mark Spalding, Robert Steneck, Reg Watson. A Global Map of Human Impact on Marine Ecosystems. Science 15 February 2008: Vol. 319. no. 5865, pp. 948-952. doi: 10.1126/science.1149345.


One response to “How to measure the ocean

  1. Pingback: A Can of Grape Soda : Edward Champion’s Filthy Habits

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