NARRATOR：

Listen to part of a lecture in an environmental conservation class.

FEMALE PROFESSOR：

Next I want to talk about the collapse of the North American cod population.

Let's look at Cape Cod, in the northeastern United States.

The area was named Cape Cod because there were so many cod fish in the waters just off its shores, so many that the first Europeans who fished there in the seventeenth century reported it was better than in Newfoundland, Canada.

At the time, Newfoundland's cod fishery was so rich that people said it was possible just to lower a bucket in the water, pull it out, and it'd be full of cod.

But Cape Cod was even better.

So the fishing industry there did great until, after the 1940s, uh, there were simply too many fishing vessels, sophisticated vessels, competing for fewer and fewer fish.

In the 1940s, there were still about 400 million pounds of fish caught at Cape Cod every year.

Just 50 years later, though, by the 1990s, commercial cod fishing there had become unprofitable; the annual catch had gone down to about five percent of its 1940s level.

And here's what's so fascinating.

As more and more fishing vessels with better and better fishing technology were competing for cod, this competition was causing changes to the biology of the fish and these changes were making it more and more difficult for the cod population to sustain itself.

FEMALE STUDENT：

[incredulously] Changes to the biology of the fish?

FEMALE PROFESSOR：

Well, if a cod fish could reproduce earlier than usual, it'd have a better chance of passing on its genes to the next generation before being caught, right?

And sure enough, biologists noticed that around Cape Cod, the cod were beginning to mature at an earlier age than normal.

Prior to the population collapse, cod usually took about 8 to 10 years to fully mature, to start to reproduce, uh, and they lived around 40 years total.

So cod had about 30 years of active reproductive life.

But now cod were beginning to reproduce at a younger age, at 3 to 4 years old.

And they were living shorter lives because they were being caught, so they had fewer years within which to reproduce.

Additionally, even though some fish in the population were maturing at an earlier age, none was actually growing faster.

No cod has a way of speeding up its rate of growth. So the younger reproductive age actually meant that smaller fish were reproducing.

And, when you are a small cod reproducing, you produce fewer eggs than a large cod... the smaller cod simply don't have the body mass to produce as many eggs.

The overfishing pressure on the cod population was pushing the cod into an evolutionary corner. they were having a harder and harder time surviving.

MALE STUDENT：

But what can be done to prevent other scenarios like this?

I mean, obviously we need a better way to manage environmental resources.

FEMALE PROFESSOR：

Well, what do you guys suggest?Carol?

FEMALE STUDENT：

Hmm... uh, maybe privatize the resource?

A private owner would want to manage the resource efficiently­ in a sustainable way.

FEMALE PROFESSOR：

[encouragingly, but wants her to consider more carefully] OK, but the problem is, privatization doesn't necessarily result in better management of an environmental resource.

Any ideas why it wouldn't?

MALE STUDENT：

Well, an individual owner might not properly assess the limits of the resource. so they could be just as prone to overexploiting that resource as a group, where lots of people have access to it.

FEMALE PROFESSOR：

Yes. Well, like in the 1970s, when it was already clear the North American cod population was declining dramatically.

The U.S. and Canada declared a 200-mile exclusive economic zone in the waters around Cape Cod.

By declaring an exclusive economic zone, you see, these two countries were trying to extend their territorial waters.

Basically, it was as if they were saying, "We're the private owners.we own these waters, so we own the rights to the fish in them too."

Essentially, the two countries told fishing vessels trawlers from all other nations to get out of the cod-fishing area.

You'd think that'd be good news for the cod because there'd be less fishing.

However, the U.S. and Canada wanted to expel foreign trawlers only in order to increase the numbers of their own fishing fleets.

The total number of fishing trawlers actually increased.

Another possible solution, pass laws that regulate use of the resource.

But for regulation to be effective, penalties for breaking the law have to be large enough to deter violators.