The Tragedy of the Marine Commons

I’ve made this parody before:

Give a man a fish, and he’ll eat for a day.
Teach a man to fish, and he’ll eat until the fish are extinct.

All indications are that our grandkids won’t be big fans of sashimi, as it will either be too expensive for them, or virtually non-existent, because we have driven the large fish species to (or near) extinction.  We’ve been making fish smaller, and less plentiful for millennia.  This is no huge surprise.  We ate all the tasty North American megafauna when we got here too.  We were hungry, and we didn’t know any better.  The world and its resources seemed vast beyond our comprehension.

by Sanctu

The situation today is tragic partly because we know exactly what we’re doing, and partly because we could be sustainably harvesting vastly more fish today than we are currently mining at an unsustainable rate, if only we could somehow contrive to let fish stocks rebound to their Pleistocene levels.  At those very high (pre-human) stocking rates, the sustainable take would be enormous, but we would have to manage the harvest carefully with quotas (which we didn’t do the first time around, and which we are much better equipped to do now).  Such quotas are sometimes discussed as if they were purely economic or political quantities, but in some important ways they are neither.

For any given level of fish stocks, there will exist a corresponding sustainable yield, and that yield is biologically determined (irrespective of what our laws or markets might say). If we choose a quota above the sustainable yield, then the stocks and thus the sustainable yield will decrease with time. If we choose a quota below the sustainable yield, then (in our current fish-depleted world) the sustainable yield will increase with time.

So then the question becomes, what are we trying to do with the quota? Maximize food production? Improve the health of the marine ecosystem? Maximize profits from fishing? If our goals are either (or both) of the first two, then clearly the right decision today (if we have a small discount rate anyway) is to choose a quota which is lower than the current sustainable yield, to allow the fish stocks to rebound, and to increase the sustainable yield in the future. Then later we can up the quota to be in line with the new, larger sustainable yield, and hold the system in steady state (assuming we understand how the system works well enough).

However, this might not be what maximizes the profits of the fishing industry, as the increased supply will likely lower prices. We could address this by keeping the quotas lower than the sustainable yield even after the oceans have recovered from our centuries of overzealous harvests, but then we would not be maximizing food production.  It’s unclear to me that all three of these possible goals can be pursued simultaneously.

I think we have a tendency to forget that there are constraints imposed on us by the natural world.  Some can be worked around, others can’t.  We structure our laws and markets as if the natural world’s regulations were mutable, as if they were a matter of debate and negotiation, as our laws and markets are, but in this respect the world of science is very different from most humanistic pursuits.  The universe doesn’t care.  It won’t negotiate.  It’s not, as Carl Sagan said, required to be in perfect harmony with human ambition.  Or Richard Feynman’s comment, in connection with the Challenger disaster:  “For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled.”

When we do finally figure out how (or are forced) to live within the bounds of sustainability, it will be a strange kind of subjugation of our collective self.  That doesn’t have to be a bad thing.