ÿþ<HTML> <HEAD> <title>Ontario Crayfish Identification Guide - Orconectes virilis</title> <meta name="keywords" content="Orconectes virilis, Virile Crayfish, virile crayfish, crayfish identification, Crayfish identification, crayfish species identification, Ontario crayfish identification"> </HEAD> <BODY BGCOLOR="#339999" VLINK="#811F78" ALINK="42426F"> <BASEFONT SIZE=1> <TABLE BORDER=3 CELLPADDING=40> <TR> <TD><TABLE ALIGN=LEFT CELLPADDING=150> <TR ALIGN=CENTER> <TD VALIGN=TOP ALIGN=LEFT BGCOLOR="#FFFFFF"><P><FONT FACE="ARIAL,SWISS"> <IMG SRC="ovirilis.jpg" WIDTH=500 HEIGHT=250 ALT="[Orconectes virilis]" ALIGN=TOP > <FONT FACE="COMIC SANS MS"> <H1 ALIGN=CENTER>Orconectes virilis</H1> <H2 ALIGN=CENTER>Virile Crayfish</H2> </ALIGN=CENTER> <ALIGN=LEFT> <FONT SIZE=2> <H3>DESCRIPTION</H3> The Virile crayfish, Ecrivisse virile, is a medium to large crayfish. It is distinguished from similar species (the Papershell Crayfish) by broad flattened tuberculate chela with straight margin of dactyl, and male gonopod morphology. It has a olive-brown body that is dappled with dark brown, abdominal segments with dark brown medial spots and chelae and legs that are distinctly blueish with yellow tubercles. Blue colour morphs of this species have been recorded on occasion (Momot and Gall, 1971). <H3>HABITAT</H3> Found in rivers, streams, lakes and ponds. The Virile Crayfish is able to survive severe weather conditions in the northern parts of its range. <H3>DISTRBUTION</H3> Canada/Ontario<BR><BR> The Virile Crayfish is the most widely distributed crayfish species in Canada. It is found from eastern Alberta (Beaver, Amisk, North Saskatchewan and Battle Rivers), through Saskatchewan (Qu'apelle, Assiniboine River, Churchill and South Saskatchewan drainages), Manitoba (Assiniboine River, Lake Winnipeg, Manitoba and Winipegosis drainages), Ontario (Great Lakes to Hudson Bay) to Quebec (Ottawa River, St. Lawrence River drainage and north) (Rawson and Moore, 1944; Aiken, 1968; Crocker and Barr, 1968; Vermeer, 1972; Talbot, 1985; Sawchyn, 1986; Clifford, 1991; Somers and Green, 1993; David et al., 1994, 1997; Dube pers. comm.). It is worth noting that Amisk River record in Alberta (54¡ 27' 00" N-111¡ 46' 00" W) is the northern-most record for any crayfish species in North America to date. North America Ð This species is wide ranging in North America where it occurs in Quebec, Ontario, Manitoba, Saskatchewan, Alberta, New York, Michigan, Ohio, Kentucky, Illinois, Indiana, Minnesota, Wisconsin, Iowa, Missouri, Arkansas, Nebraska, Oklahoma, Texas, North Dakota, Kansas, Wyoming, Montana, Colorado and Utah. It has also been widely introduced throughout the United States (Alabama, Arizona, California, Connecticut, Maine, Massachusetts, Mississippi, Tennessee, Vermont, Virginia, West Virginia, New Hampshire, New Jersey, New Mexico, Pennsylvania and Rhode Island) as well as Mexico (Chihuahua) and Europe (France and Sweden) (Hobbs, 1989; Hobbs III et al., 1989; Taylor et al., 1996). HABITAT AND ECOLOGY: It is usually not found in swift flows or rapids (Berrill, 1978). This species occurs most often on rocky substrate but it can also be found in slower flowing rivers on mud, silt and sand as well as in weedy soft bottomed lakes (Berrill, 1978; Crocker and Barr, 1968). <H3>ECOLOGY</H3> The Virile Crayfish lives in excavations under rocks but occasionally constructs extensive burrow networks in the banks of rivers such as those observed in the Wanapitei River (Hamr, pers. comm.). On the Ontario Precambrian Shield, this species has been found in lakes with higher pH (> 5.7) (David et al., 1997). It can also occur in deep water (up to 10 m/33 ft.) (Crocker and Barr, 1968). The Virile Crayfish is able to survive severe weather conditions in the northern parts of its range. Survival in these conditions is not due to any special physiological adaptations but rather migration into deeper water and it is dependent on the presence of habitat where water does not freeze to the substrate at any time of year (Aiken, 1968). Immature individuals apparently suffer higher winter-kills than adults because they do not migrate into deeper water like the adults. Laboratory studies have shown this species to have a preference for soft substrates and a fairly low station holding ability (28 cm/sec or 10.9 in./sec) in fast currents (Maude and Williams, 1983). The Virile Crayfish appears to be most active from May to September and their trapability is influenced by water temperatures and presence of predatory fish (Collins et al., 1983; Somers and Green, 1993). This species has been found together with the Appalachian Brook Crayfish, the Robust Crayfish, the Northern Clearwater Crayfish, the Papershell Crayfish, the Obscure Crayfish and the Rusty Crayfish. <H3>LIFE HISTORY</H3> In Ontario, Quebec, Saskatchewan and Alberta, the Virile Crayfish mates from July to September and perhaps again in the spring. Eggs are laid from late May to early June and hatch in July (Sawchyn, 1986; Talbot, 1985; Weagle and Ozborne, 1972). Young moult 5 times in the first summer and 3-4 times in the second. Crayfish mature within the first or second year. Mature males moult from Form I to Form II in mid-June and back again to Form I in early August. Mature females moult once only in July when their young leave. The average life span is 3 years and maximum size is 55 mm CPL at about 3-4 years of age (Sawchyn, 1986; Talbot, 1985; Weagle and Ozborne, 1972). <H3>CONSERVATION STATUS</H3> This species is widespread and common especially in the western parts of Canada. In Alberta, where the species apparently occurred naturally in the Beaver River drainage, it has been introduced by baitfishermen into water bodies up to 400 km (249 mi.) from the nearest possible source (Hanson et al.,1990) and crayfish have been reported recently from the North Saskatchewan and Battle Rivers (Saffran, pers. comm.). On the other hand, the Virile Crayfish is locally threatened in many watersheds in eastern Canada. It is presently being displaced by the introduced Rusty Crayfish in many areas of southern and northern Ontario (Berrill, 1978; Momot, 1997). Local declines may also be due to air and water pollution and associated chemical changes in watersheds. A study of crayfishes in lakes of the Canadian Shield in Ontario found a decline in the Virile Crayfish as well as other native species. It was suggested that these declines may be linked to low pH and high aluminum concentrations (David et al., 1994). Acidification of lakes has been shown to cause reductions in the fecundity of this species and it was concluded that reproductive failure could cause the disappearance of crayfish populations long before water becomes acidic enough to cause direct mortality. A pH of more than 5.8 is apparently needed for successful egg attachment (France, 1987a). Acidification also results in reduced carapace rigidity which makes crayfishes more vulnerable to predation and mechanical stress. The Virile Crayfish has been shown to be a good indicator of mercury contamination in water bodies in Ontario and Manitoba (Vermeer, 1972). Studies in the Sudbury area where emissions of heavy metals remain high showed that, although metals were accumulated, the species appeared to be tolerant to copper, cadmium and nickel (Bagatto and Alikhan, 1987). A study of the potential for commercial exploitation in various Saskatchewan rivers and lakes showed that the levels of heavy metals (mercury, arsenic, lead, copper etc.) and organic compounds (e.g. PCB, DDT, dieldrin) were at least an order of magnitude lower than levels accepted for human consumption (Sawchyn, 1986). This species has been the subject of numerous studies in Canada and, as a result, a good database dealing with its biology, ecology and physiology exists in the literature. The main gaps in knowledge remain in the documentation of its distribution, particularly in the most northern regions of its distribution and its interaction with introduced or expanding species. Despite local extinctions, the Virile Crayfish is still common and has a very extensive distribution (with many "safe" populations outside of the range of the introduced species) and must therefore be considered to have a "Currently Stable" status in Canada. <BR><BR><BR>(Used by permission: text by Premek Hamr, adapted from "Baitfish of North America"2007<BR>painting by Aleta Karstad) <BR> </TD> </TR> </FONT SIZE> </TD> </TR> </TABLE> </BODY> <FONT FACE="COMIC SANS MS"> <FONT SIZE=+2> <CENTER> <BR><BR> <A HREF="craydentpage.htm"><B>return to Identification Guide</B></A> <BR><BR> <A HREF="index.htm"><B>home</B></A> <BR><BR> </HTML>