An embarrassing case of mistaken identity

Biologists and conservationists in the US state of Colorado had egg (or should that be roe?) on their faces this week with the discovery that they had spent decades conserving the wrong fish.

A hundred years ago things were looking pretty grim for the greenback cutthroat trout. Pollution from mining, overfishing and competition from imported trout species caused its population to decline, and in 1937 it was officially declared extinct.

Then in the 1950s, a few small populations of greenbacks were found in the Rocky Mountains' rivers. In the 1970s, the fish was officially placed on the "endangered species" list and state and federal fish managers embarked on a programme to bring the greenback back from the brink of extinction. For decades, they took eggs and sperm from wild fish and lovingly reared the resulting baby fish in hatcheries before releasing them back into their natural habitat.

All seemed to be going swimmingly (if you'll pardon the expression), as the newly established populations took hold and greenback numbers swelled. In 2006, the Colorado Division of Wildlife proudly announced that it had reached its goal of establishing 20 self-sustaining greenback populations and maybe, just maybe, the species could be taken off the endangered list.

However, new research published in the latest edition of the journal Molecular Ecology reveals a serious case of mistaken identity. Put simply, some of the new populations are not greenback cutthroat trout at all, but Colorado River cutthroat trout. It's an easy mistake to make; the two subspecies do look very similar (the greenback has larger but fewer spots, apparently).

Nevertheless, the study means that the greenback's fate is still in the balance, as DNA studies show that its range consists of just 11 miles of streams in remote areas of Colorado. "The new study means that we have not reached the targeted management goals, and the species is no closer to being removed from the endangered species list than when it originally was listed," commented Professor Andrew Martin of the University of Colorado, one of the authors of the study.