The Dilemma of Delisting Species

Gerber and her colleagues are not arguing for a relaxation of the standards, but she notes that unless the criteria for “delisting” is explicit and clear for each species, there is grave danger that decisions will be based more on politics and economics than science.

And whenever the evidence is compelling, animals and plants that have rebounded ought to be removed or the list will become “just a list that isn’t really doing anything,” she says.

But what is most essential, she says, is for scientists to come up with clear criteria that will allow policy makers to decide when success has been achieved. And that’s tough.

It’s different for each species, and it can take decades to collect the data needed for good judgment. In some cases, the data is very difficult to get, and in other cases the animal makes it a lot easier.

Missing Data

Take the case of whales. Commercial whaling so decimated whale stocks around the world that nearly all whales were listed as endangered and are now protected under international treaties. But not all whales are the same.

Each year, almost like clockwork, the Northern Pacific gray whale passes the shoreline of California on its way to it’s spawning grounds off Baja California, giving scientists the opportunity to monitor its numbers quite reliably. The grays have enjoyed a steady growth rate to a population of about 26,635 individuals. As a result, in 1994, the gray whale became the only large whale to be “delisted.”

But other whale species, including the humpback, are less predictable in their migratory habits, leaving scientists largely guessing at their numbers. And there are so few North Pacific right whales that no one is sure just how many there are, but it’s probably fewer than a hundred animals at best.

So what was good for the gray was not necessarily good enough for the right whale, which may be headed for extinction.

“We haven’t seen a calf in years,” Gerber notes, adding that the whales may be so few in number that they are having problems finding mates and thus may not be reproducing at a sustainable rate.

But, as she quickly adds, no one really knows that.

Getting answers to questions like that could take decades and buckets full of research money. And none of that will help until someone with a lot of clout decides that the Endangered Species Act may itself be endangered if scientists can’t come up with the facts.

Only then will we know if the bald eagle is, again, master of the skies.

Lee Dye’s column appears weekly on A former science writer for the Los Angeles Times, he now lives in Juneau, Alaska.

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