[Pierre]

Jim Stelfox previous wrote the following on another forum a number of years ago.

Northern Dolly Varden were introduced to Chester Lake in 1974 and have since dispersed into Mud Lake, Burstall Creek and Smuts Creek. To my knowledge, this is the only place that Dolly Varden are present in Alberta.

Differentiating between Dolly Varden and bull trout isn't easy. Gordon Haas, one of the foremost experts on identification of these two species, sums it up best when he stated in his 2001 paper in the Bull Trout II Conference Proceedings that "correct identification of these two char species....is complex and requires identification ability and knowledge.

In general, the easiest way to usually differentiate between these two species is that bull trout have a flatter head and the maxilla extends further back of the eye. These are subjective features, necessitating the examination of a lot of fish of both species in order to have much confidence.

However, anglers need not be concerned about differentiating between these two species, because Dolly Varden can only be harvested from Chester Lake and its outlet stream and there are no bull trout in these waters. If you catch a Dolly Varden in Mud Lake, Burstall Creek or Smuts Creek, you have to release it, just as you would a bull trout.

Page 284-286 in the Nelson & Paetz book - The Fishes of Alberta provides more info.
A quote from the book:

"There is some doubt about the exact origin of the stock put into Chester Lake. Eggs from two different studies were held in Calgary in 1973-74, one said to be from the Mackenzie (Inuvik stock) and the other from the Firth River (Yukon)......It is, of course, quite possible, if not probable, that the eggs used by both McCart and McDonald came from the same source (i.e., the Firth River, then shipped to Calgary via Inuvik"