Spiny scale crayfish (Cambarus jezerinaci)

Also known as: Powell River crayfish
GenusCambarus (1)

The spiny scale crayfish is classified as Data Deficient (DD) on the IUCN Red List (1).

The spiny scale crayfish (Cambarus jezerinaci) is a member of the genus Cambarus, which comprises approximately 20 percent of the world’s 500 or so crayfish species and about one third of all North American crayfish (2). Described as recently as 2000 (3), this species was once considered conspecific with Cambarus parvoculus, but is now recognised as its own species due to unique genetic and morphological characteristics (1) (4). 

Like other crayfish, this large freshwater species has a carapace that protects the head and internal organs. The six segments of the abdomen are individually encased, with a flexible membrane between them to allow movement. Crayfish also have a pair of large fore-claws, followed by four pairs of walking legs and then four pairs of small swimming legs, called ‘swimmerets’. These swimmerets are covered with fine hairs, to which the female attaches her eggs. A central tail flap is surrounded by four other flaps that are used to move the crayfish rapidly through the water, as well as curling up to form a brood chamber. The eyes are each borne on an eyestalk, while a pair of large feelers (or antennae) and a pair of small, fine, centrally-located feelers (or antennules) make the crayfish’s sense of touch and taste particularly sensitive.

Occurring in the states of Kentucky, Tennessee and Virginia in the U.S, the spiny scale crayfish is found in small tributaries of the Powell River, as well as the Powell River basin, the Cumberland River and the upper reaches of the Kentucky River (1) (5).

The spiny scale crayfish tends to be found in high altitude, high gradient spring-fed streams, where it occupies burrows created by other species (1) (5).

Owing to the recent discovery of the spiny scale crayfish and the lack of studies targeting this species, there is very little information available on its specific biology.

North America possesses the highest diversity of crayfish in the world, with around 77 percent of the world’s crayfish found there (2). In total, around 308 crayfish species have been described in North America, most of which are found in the south-eastern regions of the U.S (6). 

Despite the exceptional diversity of crayfish in North America, there is very little information on the conservation status of most species. However, around 50 percent are thought to be in need of some conservation attention, primarily as a result of their limited range, as well as the alteration of their habitat. Changes to crayfish habitat in the form of dams affects the physical and chemical structure of streams, while the removal of boulders, gravel, wood debris and vegetation can reduce the amount of cover available for crayfish. Without such cover crayfish are vulnerable to predation. Species with a small range are also particularly vulnerable to habitat destruction and degradation by stream channelling, dredging and mining (6). 

Declines in spiny scale crayfish populations have been observed in Virginia, due to forestry activities and mining. This species is probably also undergoing some localised population declines as a result of water pollution and alterations to its habitat (1). An additional threat to the spiny scale crayfish is global climate change (1), which may cause some southern areas of the U.S. to become less suitable for species that prefer cooler waters (2).

With such little information available on the status of the spiny scale crayfish, a conservation priority for this species is further research to determine its population size and distribution and whether it is impacted by any major threats, as well as further studies into its ecology (1).

Find out more about conservation in the U.S:

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  1. IUCN Red List (May, 2011)
  2. Guiaşu, R.C. (2009) Conservation, status, and diversity of the crayfishes of the genus Cambarus Erichson, 1846 (Decapoda, Cambaridae). Crustaceana, 82: 721-742.
  3. Thoma, R. (2000) Cambarus (Jugicambarus) jezerinaci (Crustacea: Decapoda: Cambaridae) a new species of crayfish from the Powell River drainage of Tennessee and Virginia. Proceedings of the Biological Society of Washington, 113(3): 731-738.
  4. Thoma, R.F. and Fetzner, J.W. (2008) Taxonomic status of Cambarus (Jugicambarus) jezerinaci, spiny scale crayfish (Powell River crayfish). Virginia Department of Game & Inland Fisheries, Richmond, Virginia.
  5. NatureServe Explorer - Cambarus jezerinaci (May, 2011)
  6. Taylor, A.C. et al. (1996) Conservation status of the crayfishes of the United States and Canada. Fisheries, 21: 25-38.