Much ado is often made of the differences between very similar fish. While arctic char have long been prized for their beauty and succulent sweet flesh, Dolly Varden char have not always had the same cachet.

And then there are bull trout. Now the focus of major conservation efforts in Alberta, British Columbia, and the western United States, bull trout were thought of as garbage fish only a few decades ago.

In fact, these three members of the char family are extremely difficult to tell apart. Yukon fisheries officials are now relying on genetic tests, the only conclusive way to tell one species from another, to confirm which species live where in the territory.

"The difference between the species is a point of contention among scientists," says Susan Thompson, a fisheries biologist with the Yukon government.

For example, in the 1970s the char in the Bonnet Plume River were classified as Dolly Varden, but Thompson says that they could well be arctic char or even bull trout. Last July, fisheries staff sent fry from the Bonnet Plume, Blackstone and Ogilvie River to the University of British Columbia for genetic testing.

The char in the Blackstone, a tributary of the Peel, were assumed to be arctic char, and many sources still refer to arctic char as living further north than any other freshwater fish. Now it is known that Dolly Varden char also live in arctic drainages.

Thompson says that the usual rule of thumb has been that arctic char are found east of the Mackenzie River and Dolly Varden char are found west of it. But that clear-cut line could also fall by the wayside as more genetic tests are done.

Bull trout were once considered to be the inland variety of Dolly Varden, but they are now proven to be a separate species. No one knew that there were any bull trout in the Yukon until about two years ago when genetic tests showed that they live in both the Liard and Rancheria Rivers.

Few fish have experienced a change in popularity like the bull trout. After the turn of the century, when game species such as brook trout were introduced into streams, bull trout became an unwanted competitor; these big aggressive fish preyed on the new arrivals, so systematic efforts were made to exterminate the bull trout.

Montana encouraged commercial net fishing of the species. Sometimes dynamite was used to blast them out of streams. In Alberta bull trout disappeared from about half of their historic range before people became concerned about the species' survival.

Now Alberta's official fish, the bull trout is getting lots of help at making a comeback in that province. In the United States bull trout were reduced to about 5 percent of their historic range, and have recently been listed as an endangered species. This move has been referred to as one of the most significant listings ever made in the U.S. because of the extensive historic range of bull trout throughout the Pacific Northwest.

In the Yukon, fisheries managers are trying to ensure that the species does not suffer the sorts of problems that it has experienced down south. A brood stock of bull trout is now being established in a pothole lake near Whitehorse. Thompson hopes that once they start stocking other lakes with bull trout, there will be less pressure on this species in the Liard drainage.

Bull trout are very susceptible to habitat destruction and overfishing. They are slow to mature and they will seldom pass up a free meal, which makes them easy to catch. "You can go into areas where bull trout spawn and catch every one of them," says Thompson.

She says that managing these three closely related species is a learning exercise for everyone involved. "We're trying to learn and to educate anglers because the three species have different management requirements. We want to inform people about how to tell them apart."

Part of the process will be pinning down exactly where the different species live in the territory. Thompson says she finds this process fascinating and decidedly easier these days. Not so long ago fisheries managers had to take dozens of measurements on a fish to try and determine the species. Now, with genetic testing, they can tell conclusively whether a fish is a Dolly Varden char or a bull trout or an arctic char.

For more information on fisheries and fishing in the Yukon, contact the Yukon Department of Renewable Resources at 667-5652.