Thursday, January 29, 2009

Tragedy of the Commons Applied

Last week, I spent part of my time at work reviewing old VHS tapes. ASOC is trying to add more interactive materials to the website and the programs on many of the tapes would be great additions. Many of the tapes that I watched that Tuesday had to do with the Chilean Sea Bass ban in major cities across the U.S. As I was watching the interview with former ASOC employee Beth Marks, I thought about how the Chilean Sea Bass problem illustrated a concept I have learned about in all of my environmental policy classes - the Tragedy of the Commons.

The Tragedy of the Commons is an idea developed by Garrett Hardin in his article "The Tragedy of the Commons" (published in Science, 1968). This influential article talks a lot about population size as well (Hardin believed that the population problem is a problem for which there is no technical solution; the only answer to the problem is, well, a reduction in the Earth's population), but I'll save that discussion for a later post. Instead, let me begin with a brief summary of the tragedy of the commons as Hardin explains it:

Hardin asks us to imagine a society of herdsmen (of a significant and stable number) that shares open access to a single pasture. Each herdsman is allowed to keep and graze as many cattle there as he chooses. Naturally, we assume that each of the herdsmen seeks to maximize his gain. Hardin posits that each herdsman would consider the utility of adding one more animal to their herd. This utility, according to Hardin, would have one negative and one positive component.

The positive component is that the herdsman would have one more animal. He and only he receives the benefit of having this animal. We can quantify this as +1.

The negative component is the effects of overgrazing on the pasture. This negative effect is felt by all the herdsmen, so we can quantify this as a fraction of -1.

Since the herdsman in question realizes that he will benefit from the addition of the new animal, it is logical for him to expand his herd. All other herdsmen in the society would come to the same conclusion. Thus, the total number of animals grazing on the pasture would increase until the damage from overgrazing left the pasture defunct.

The tragedy lies in the fact that these herdsmen are living within a system that encourages them to increase the size of their herd/their profit without limit, in a world where resources are limited.


The Chilean Sea Bass illustrates the tragedy of the commons in that overfishing has caused a decline in the fishes' population. I'll discuss numbers next week, but in the meantime, here's a bit of background on this fish we call the "Chilean Sea Bass."

Chilean Sea Bass is the marketing name for two separate but related fish, the Patagonian Toothfish and the Antarctic Toothfish (also called the Antarctic Cod). Both fish live in the cold waters of the Southern Hemisphere -the Patagonian Toothfish can be found in the South Pacific, the Indian Ocean, the Southern Ocean, and the Southern Atlantic; Antarctic Toothfish live only in the Southern Ocean - the waters surrounding Antarctica. Both fish are slow growing and slow to mature (this is a result of their having adapted to living in cold temperatures), meaning that they reproduce later in life relative to many other species of fish. Consequently, when large numbers of fish are harvested, it takes longer for the species to repopulate.

Next week I'll be back with more on the "Chilean Sea Bass."

For information on environmentally friendly seafood, check out Seafood Watch.

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