RANGE EXTENSION OF THE NORTHERN CRAYFISH, ORCONECTES VIRILIS (DECAPODA, CAMBARIDAE), IN THE WESTERN PRAIRIE PROVINCES OF CANADA

BY

B. W. WILLIAMS1,3),H.C.PROCTOR1) and T. CLAYTON2) 1) Department of Biological Sciences, University of Alberta, Edmonton, T6G 2E9, Alberta, Canada 2) Fish and Wildlife Division, Alberta Sustainable Resource Development, YPM Place, 530 8 St. South, Lethbridge, T1J 2J8, Alberta, Canada

ABSTRACT

The northern crayfish, Orconectes virilis (Hagen, 1870), is the northernmost-ranging crayfish species in North America. However, little is known of the distribution of O. virilis in the western Prairie Provinces of Canada, which comprise the northwestern portion of the species’ contiguous range. We combined extensive sampling data with confirmed reports of crayfish to describe a recent westward range expansion and the current distribution of O. virilis in Saskatchewan and Alberta. The reports suggest that the vast majority of colonization of the western Prairie Provinces may have resulted from natural movement, although anthropogenic introduction may be, in part, responsible for the described expansion of O. virilis. The description of potential movement patterns and current range has implications for the continued monitoring and management of the species across the region.

RÉSUMÉ

L’écrevisse Orconectes virilis (Hagen, 1870), est la plus nordique des espèces d’écrevisse en Amérique du nord. Cependant peu de choses sont connues sur la distribution de O. virilis dans les provinces des prairies de l’ouest du Canada, qui comprennent la portion nord-ouest de la distribution en continu de l’espèce. Nous avons associé les nombreuses données d’échantillonnage avec les signalements confirmés de l’écrevisse pour décrire l’expansion récente vers l’ouest et la distribution actuelle de O. virilis dans le Saskatchewan et l’Alberta. Les rapports suggèrent que l’essentiel de la colonisation des prairies de l’ouest du Canada peut avoir résulté d’un mouvement naturel, bien qu’une introduction anthropique peut être, en partie, responsable de l’expansion constatée de O. virilis. La description des modèles des mouvements potentiels et de la distribution actuelle a des implications sur le suivi en continu et le management de l’espèce à travers la région.

3) e-mail: [email protected] © Koninklijke Brill NV, Leiden, 2011 Crustaceana 84 (4): 451-460 Also available online: www.brill.nl/cr DOI:10.1163/001121611X563995 452 B. W. WILLIAMS, H. C. PROCTOR & T. CLAYTON

INTRODUCTION

The widespread northern or virile crayfish, Orconectes virilis (Hagen, 1870), has the northernmost range of any crayfish species in North America (Hamr, 2002). Although it is the only species of crayfish known to occur in Saskatchewan and Alberta, Canada, little is known about the details of the distribution of O. virilis in these provinces, as evidenced by question marks in the species range map of Crocker & Barr (1968: 95), and more recently that of Hamr (2002: 586). The earliest records of O. virilis in the Prairie Provinces were provided by Hagen (1870) and restated in the works of Faxon (1885), Harris (1903), and Huntsman (1915). These records were limited to collections made from Lake Winnipeg, the Red River, and Saskatchewan River in Manitoba during the Assiniboine and Saskatchewan Exploring Expedition of 1858. The first published records of O. virilis in Saskatchewan were provided by Rawson & Moore (1944), who found the species to be common in lakes in the Qu’Appelle River drainage in east-central Saskatchewan, as well as the Saskatchewan River drainage and Lake Winnipegosis drainage in northeastern Saskatchewan. In addition, Rawson & Moore (1944) reported the presence of O. virilis in Cold Lake on the Saskatchewan-Alberta border in the Beaver River drainage, a distribution later extended westward along the Beaver and Amisk rivers of Alberta (Aiken, 1968a). Unfortunately, Rawson & Moore (1944) appear to have been missed in subsequent descriptions of the range of O. virilis (cf. Aiken, 1968a; Crocker & Barr, 1968). Although Crocker & Barr (1968) and Aiken (1968a) described the range of the species reaching into Saskatchewan, they inaccurately referenced the early works of Faxon (1885), Harris (1903), and Huntsman (1915), which had provided records no further west than western Manitoba. Despite its presence in the Beaver River system of northern Alberta (Aiken, 1968a), O. virilis appears to have been historically absent from much of the western Prairie Provinces. Although their survey sites were restricted to lakes, Rawson & Moore (1944) noted that crayfish were not found in any of the sampled areas in the central or western part of Saskatchewan. Aiken (1967, 1968a) failed to detect crayfish outside of the Beaver River drainage during an extensive survey across Alberta in 1964 (fig. 1). A macroinvertebrate study in the Oldman and South Saskatchewan rivers of southern Alberta during 1975-77 (Culp & Davies, 1982) also failed to detect the presence of O. virilis. Similarly, crayfish were not encountered during intensive invertebrate collections in the Battle River in Alberta in the late 1980s (A.-M. Anderson, Alberta Environment, pers. comm.). In the early 1990s, anglers began reporting crayfish catches and sightings (e.g., live individuals, moulted carapaces, and dissociated chelae) in areas of Alberta outside of the Beaver River drainage. As a means of assessing the apparent