[Cambarus bartonii]

Cambarus bartonii

Common Crayfish


The Appalachian Brook Crayfish is also known as Ecrevisse du Nord. It is a medium to small crayfish with generally smooth appearance, small eyes set into the carapace and smooth chela with fingers curved inwards. It is distinguished from the similar species the Robust Crayfish by a shorter rostrum and single row of tubercules on inner border of palm of chelipeds. Colouring is characteristically orange-brown but can also be blueish-green. Blue morphs of this species have been recorded in Ontario (Crocker and Barr, 1968; Hamr, unpublished data).


Found in streams, rivers and lakes. The Appalachian Brook Crayfish is most common in fast flowing, rocky areas which remain cool and well oxygenated in the summer. It is therefore often associated with rapids and waterfalls.



This species is found in New Brunswick, Quebec and Ontario. In Ontario, where its distribution has been well documented, it is found from the Moose River drainage in the north, westward to the eastern shore of Lake Superior, south to the western end of Lake Ontario and east to the Ottawa-St. Lawrence River drainages (Crocker and Barr, 1968; Berrill 1978; Hamr 1983; David et al., 1994, Guiasu et al., 1996; David et al., 1997;). In Quebec its distribution remains largely undocumented but it occurs in both the St. Lawrence River and Ottawa River drainages. To date it has been collected from the Ottawa region south to Montreal and eastward, on both north and south shores of the St. Lawrence River to the Madawaska drainage on the New Brunswick border (Bousfield, 1969; Burgess and Bider, 1980; Schueler, 1985; Dube (unpublished records); Hamr (unpublished records). The species is also found in the Laurentides region north of the St. Lawrence River (Dube, unpublished records) and it is very likely to range as far north as James Bay. In New Brunswick, Cambarus bartonii is found in the Saint John, the Restigouche and in the Miramichi drainages. No crayfishes have been observed in any of the Northumberland Strait or in east Bay of Fundy rivers (Schueler, 1985; Hooper pers. comm.). North America This species is widely distributed along the eastern part of North America and has been recorded from New Brunswick, Quebec, Ontario, Maine, Massachusetts, Rhode Island, Vermont, New York, New Jersey, Connecticut, Pennsylvania, Maryland, District of Columbia, Delaware, Virginia, West Virginia, Kentucky, Tennessee, North Carolina, South Carolina, Georgia and Alabama.


This species is most common in fast flowing, rocky areas which remain cool and well oxygenated in the summer(Crocker and Barr, 1968; Bousfield, 1969; Berrill, 1978; Hamr and Berrill, 1985; Guiasu et al., 1996). Shelters usually consist of excavations in gravel and sand under larger rocks (Crocker and Barr, 1968; Hamr, 1983). The species shows a remarkable ability to penetrate deep into the substrate. Excavations can go as deep as 1 m throughout several layers of rock and gravel (Hamr, 1983). On the Canadian Shield in Ontario, this species has been found in deep, high elevation lakes spanning abroad range of pH values (5.0->7.0)(David et al., 1994). In Canada, this species has been found together with Robust Crayfish, Northern Clearwater Crayfish, Virile Crayfish, Obscure Crayfish, Papershell Crayfish and Rusty Crayfish (Berrill, 1978; Hamr, 1983; David et al., 1997). In laboratory studies Cambarus bartonii was found to be clearly more aggressive than Virile Crayfish and Northern Clearwater Crayfish but less aggressive than Robust Crayfish (Guiasu and Dunham, 1997).


In Ontario, reproduction appears to take place from spring to fall. Mature females show strong glair gland development from April to August. Copulation has been observed in October in the wild and late April to early June in captivity. Females with eggs are found from June to August and with young from July to September. Eggs and young are therefore carried into autumn and there is evidence that some females may over winter with attached eggs or young and release them (and then moult) the following summer (MacManus, 1960b; Hamr, 1983). Hatching occurs between July and August and the young undergo two moults in their metamorphosis, spending about 15 days attached to their mothers. Free-living young measuring about 5 mm (0.195 in.) CPL are first found in August (Hamr, and Berrill, 1985). Moulting in immature crayfishes take place form May to early October and maturity is reached at about 2 years of age. Adult males moult in July and September. Moulting into both Form I and Form II at the same time of year has been observed (Hamr and Berrill, 1985). Mature females moult once following the reproductive season but the timing of moult is variable (September or the following June-July) depending on local conditions. The average life-span appears to be 3 years old and the maximum life-span is 4 years. The maximum recorded size is 39 mm (1.52 in.) CPL from a male collected in Rawdon, Quebec. Sexual dimorphism with respect to chela length between sexes and Form I and From II males is present but not as pronounced as in the Orconectid crayfishes (Hamr and Berrill, 1985).


Although this species remains fairly common in certain parts of Ontario, many recent collections come primarily from within protected areas inside provincial parks and conservation areas where riparian vegetation surrounding streams is well preserved and the level of water pollution and human interference is generally lower than elsewhere (Barr, 1996). Similarly, populations of this species have been found in waters infested with the introduced Rusty Crayfish (e.g. Otonabee River, Ontario). A major environmental pressure is the gradual acidification of lakes and streams due to acid rain, particularly in southeastern Ontario (DiStefano et al., 1991). Although mature Cambarus bartonii appear to be somewhat acid tolerant, it has been demonstrated that juvenile and moulting crayfishes may be more vulnerable to the acidification process than larger, intermoult individuals (Berrill et al., 1985; DiStefano et al., 1991). A study of crayfishes in lakes of the Canadian (Precambrian) Shield in Ontario found significant decreases in the Cambarus bartonii populations. It was suggested that these declines may be linked to low pH and high aluminum concentrations (David et al., 1997). Studies of this species in the Sudbury area where emissions of heavy metals remain high, showed that although metals were accumulated the species appeared to tolerant of copper, cadmium and nickel (Bagatto and Alikhan, 1987; Zia and Alikhan, 1989). The closely related Robust Crayfish has been shown to be clearly dominant in aggressive interactions with Cambarus bartonii and the distribution of the two is largely non- overlapping. Given the apparent range expansion of Robust Crayfish in Ontario and Quebec during the past 30 years it appears that this species has the potential to competitively exclude Cambarus bartonii if the two species are competing for limited resources (Guiasu and Dunham, 1997). In conclusion, this species has a fairly extensive distribution with apparently many "safe" northern populations and should therefore be considered to have a "Currently Stable" status in Canada (Hamr, 1998).

(Used by permission: text by Premek Hamr, modified from "Baitfish of North America"2007
painting by Aleta Karstad)

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