You're listening to Shortwave from NPR.

Consider the gray whale.

Humans killed around 3 million whales in a period of like 70 years or so.

In some species like the gray whale, certain populations drop to just 5% of their historic numbers.

And we stopped hunting them pretty much because we'd killed so many of them that it was no longer

economically viable to keep hunting them. That's Joshua Stewart, a marine ecologist at

Oregon State University. And he says along the way, the public took notice after a biologist

and conservationist named Roger Payne put whale songs on a vinyl record.

And folks said, wow, how could we possibly be killing these animals? We have to stop this.

Yeah. could we possibly be killing these animals? We have to stop this. So that was in the 70s. That was sort of the birth of the modern conservation movement.

In the 1980s, the international moratorium on whaling went into effect, and numbers started to climb.

All the way through 1994,

when numbers rebounded so much that the gray whale was officially removed from the endangered species list. But then 1999 happened. And then hundreds of whales start washing up dead on beaches all along the west coast of the U.S., Canada, and Mexico.

The same thing happens the next year in 2000. Hundreds more wash up dead.

And these are just the whales that people see dead on the beach.

It doesn't include the ones that die at sea during their more than 10,000-mile round-trip

migration to the Arctic.

This is where they eat enough to last them the entire year.

So Josh says, scientists estimated thousands of whales died, accounting for about a quarter

of the population.

Everybody's wondering what caused this.

We thought they were doing so well.

...