Microsoft Word - SustainabilityReport_BCC.doc

CHAPTER 4

Managing Human-Environmental Systems for Sustainability

To be useful, sustainability science needs to guide decision-making.

Chapter 4 lays out the mathematical sciences tools needed to put together

what we know into a precisely defined set of questions and into a practical

course of action.

Fish don’t stop at international borders. They swim where they will, paying

no heed to which country owns the territorial waters they’re swimming in. This

willfulness creates nasty problems for fishery managers – problems that have led

to disputes between nations, broken agreements, and the collapse of fisheries.

And some of these problems are ones that only mathematics can solve.

Pacific salmon are a prime example: They migrate along the Pacific

Northwest coast of the U.S., past Canada, and along the coastline of Alaska

before looping back to return to the precise river they hatched in themselves to

lay their eggs and die. The result is that Canadian fishermen inevitably catch fish

hatched in U.S. waters and vice-versa – and if either country overfishes, both

lose.

In 1985, the two countries came to an apparently simple solution to the

problem: fish trading. Each country would harvest fish in proportion to the

number produced in their own rivers. That way, if one of the countries invested in

habitat restoration, say, and increased its fish population as a result, it would

reap the benefits of its efforts.

The solution turned out to be a bit too simple. Climate shifts (unrelated to

global warming) caused the number of adult salmon in Alaskan waters to explode

while the number along the Pacific Northwest and Canada dwindled. Alaskan

fishermen harvested record numbers of fish, many hatched in Canada. Canada

couldn’t catch enough salmon from the reduced numbers in their own waters to

balance it out. Worse yet, Alaska had no motivation to change the agreement,

since it was profiting handsomely.

By 1993, the agreement had broken down entirely. The results were

predictable: Some fish stocks crashed. It was a classic case of what game