Pteronarcys californica in Alberta?

I responded to an e-mail from a local fly angler the other day regarding the presence of the stonefly species Pteronarcys californica (aka the Salmonfly) in Alberta. Apparently there is some debate among Alberta fly anglers as to whether or not this species is actually present in the province, and if the many Salmonfly hatches observed by anglers on their local trout streams are indeed P. californica.  

There are relatively few records in the scientific literature for P. californica in Alberta. Most of these references are from studies done on the Crowsnest River in Southern Alberta (see for example Townsend and Pritchard, 2001). The paucity of official scientific records for this and other aquatic insect species can be attributed to the lack of province wide sampling required to fully understand the full distribution of most aquatic invertebrates in Alberta. I have personally collected mature P. californica nymphs from Prairie Creek and the lower end of the Clearwater River near Rocky Mountain House. So the short answer to the first question is yes, P. californica is definitely present in Alberta.

Local authors have also written about the legendary Salmonfly hatches on several Alberta trout streams. Of course the P. californica hatch on the Crowsnest River is the most well-known but hatches have also been documented on Prairie Creek, Clearwater River, and the Red Deer River. We also know that P. californica is common on the pacific side of the Rockies, and in streams and rivers on both sides of the Rockies south of the border. In Alberta they are found only in sporadic pockets along the east slopes of the Rockies.

Pteronarcys californica nymph from the Clearwater River

So what about all of the other purported sightings of Salmonflies that have been discussed on local fly fishing forums?

See for example: http://forum.nlft.org/index.php?showtopic=3484&mode=threaded&pid=22939

I think much of the confusion comes from anglers erroneously assigning the term Salmonfly to any large dark colored fluttering bug they see streamside. There are several stonefly species in Alberta (not to mention other insect orders) that come close to the size of P. californica, making the potential for misidentification significant. Without considerable experience, a good close look, and sometimes an actual specimen in hand (or under the microscope), these sightings are just not reliable. To further complicate matters, both the adults and nymphs of Pteronarcys californica are easily confused with Pteronarcys dorsata, another more widespread stonefly species found in Alberta. P. californica and P. dorsata are quite similar in appearance, have similar life history and habitat requirements, and sometimes coexist in the same stream. In short, unless you are on a stream known to harbor a population of Salmonflies, any large dark stonefly that you see is unlikely to be P. californica – the only way to be sure would be to collect a specimen and have it identified by an experienced entomologist.

References:

Townsend, G.D. and G. Pritchard (2001). A comparison of methods for analysis of a long aquatic insect life history: Pteronarcys californica (Plecoptera) in the Crowsnest River, Alberta. In: Trends in Research in Ephemeroptera and Plecoptera. Ed. E. Dominguez. Kluwer Academic/Plenum Press, pp. 251-258.