28 July, 2010

While climate change is the 800-pound gorilla of ecological issues, I don’t want it to completely dominate the conversation here. There are a lot of other issues to think about. For example, overfishing!

My friend the mathematician John Terilla says that after we had dinner together at a friend’s house, he can’t help thinking about overfishing — especially when he eats fish. I’m afraid I have that effect on people these days.

(In case you’re wondering, we didn’t have fish for dinner.)

Anyway, John just pointed out this book review:

• Elizabeth Kolbert, The scales fall: is there any hope for our overfished oceans?, New Yorker, August 2, 2010.

It’s short and very readable. It starts out talking about tuna. In the last 40 years, the numbers of bluefin tuna have dropped by roughly 80 percent. A big part of the problem is ICCAT, which either means the International Commission for the Conservation of Atlantic Tunas, or else the International Conspiracy to Catch All Tunas, depending on whom you ask. In 2008, ICCAT scientists recommended that the bluefin catch in the eastern Atlantic and the Mediterranean be limited to 8500-15,000 tons. ICCAT went ahead and adopted a quota of 22,000 tons! So it’s no surprise that we’re in trouble now.

But it’s not just tuna. Look at what happened to cod off the east coast of Newfoundland:

In fact, there’s evidence that the population of all kinds of big predatory fish has dropped 90% since 1950:

• Ransom A. Myers and Boris Worm, Rapid worldwide depletion of predatory fish communities, Nature 423 May 15, 2003.

Of course you’d expect someone with the name “Worm” to be against fishing, but Myers agrees: “From giant blue marlin to mighty bluefin tuna, and from tropical groupers to Antarctic cod, industrial fishing has scoured the global ocean. There is no blue frontier left. Since 1950, with the onset of industrialized fisheries, we have rapidly reduced the resource base to less than 10 percent—not just in some areas, not just for some stocks, but for entire communities of these large fish species from the tropics to the poles.”

In fact, we’re “fishing down the food chain”: now that the big fish are gone, we’re going after larger and large numbers of smaller and smaller species, with former “trash fish” now available at your local market. It’s a classic tragedy of the commons: with nobody able to own fish, everyone is motivated to break agreements to limit fishing. Here’s a case where I think some intelligent applications of economics and game theory could work wonders. But who has the muscle to forge and enforce agreements? Clearly ICCAT and other existing bodies do not!

But there’s still hope. For starters, learn which fish to avoid eating. And think about this:

It is almost as though we use our military to fight the animals in the ocean. We are gradually winning this war to exterminate them. And to see this destruction happen, for nothing really – for no reason – that is a bit frustrating. Strangely enough, these effects are all reversible, all the animals that have disappeared would reappear, all the animals that were small would grow, all the relationships that you can’t see any more would re-establish themselves, and the system would re-emerge. So that’s one thing to be optimistic about. The oceans, much more so than the land, are reversible…Daniel Pauly