- Cancer astacus Linnaeus, 1758
- Astacus fluviatilis Fabricius, 1775
Noble Crayfish, Red-footed Crayfish, European Crayfish, Broad-clawed Crayfish, Red-clawed Crayfish, Broad-fingered Crayfish
IUCN: VU; Be (III); EUHD (V); RDBUkr: Вразливі
Value of species
Astacus astacus is comprised of 3 sub-species: Astacus astacus astacus, Astacus astacus balcanicus, Astacus astacus colchicus.
The Noble Crayfish, Astacus astacus, is indigenous and widespread throughout Europe. This species range extends from Russia and the Ukraine in the east, to Finland, Sweden, Norway in the north, to Greece in the south, and the United Kingdom and France in the west. A few recently introduced subpopulations are found outside Europe, for example Morocco. The occurrence of this species within Andorra, Cyprus, the UK, Liechtenstein, Luxembourg, Morocco and possibly Montenegro and Italy, is via introductions from neighbouring countries.
Natural subpopulations of the Noble Crayfish have been declining across Europe since the introduction of crayfish plague in the mid nineteenth century (Holdich 2002). This species used to be the main target of crayfish trapping in Europe, but this industry is now much reduced in central, eastern and southern Europe (Ackefors and Lindqvist 1994). Current harvest levels are only about 10% of those before the spread of the disease, despite restocking of affected lakes from aquaculture fisheries (Holdich 2002). The largest remaining subpopulations of this species are in Norway, Sweden, Finland and Denmark (Ackefors and Lindqvist 1994). Note that rates of decline have been calculated over a 22.5 year period (three generation lengths).
This species is found in rivers, lakes, ponds, and reservoirs, in both lowlands and hills, where shelter availability is high (Souty-Grosset et al. 2006). This includes stones, logs, roots and aquatic and marginal vegetation. This species prefers soft bottoms with some sand and is not usually found in water bodies with a muddy substrate. In addition, it prefers soft banks where it constructs simple burrows. The oxygen demands of this species can be quite high, leading to high mortality in shallow, eutrophic ponds during summer months (Souty-Grosset et al. 2006). Habitat of this species is shared by the introduced Pacifastacus leniusculus, which is known to competitively exclude this species after a period of establishment (Souty-Grosset et al. 2006).
This species is capable of tolerating lower calcium levels, as low as 2-3 mgl-1 Ca, where other species of crayfish may be excluded. The optimum temperature for best growth is between 16 and 24oC, although up to 28oC can generally be tolerated. In addition, oxygen content below 3-4 mgl-1 is deemed unsuitable for this species.
This species is mainly predated upon by the common eel, in addition to small scale predation by mink, perch, otter and wading birds (Souty-Grosset et al. 2006), although predation risk also includes cannibalism. This competition, along with temperature gradients and shelter availability, is the major determinant of this species range (Abrahamsson 1966, Skurdal and Taugbol 2002).
Anecdotal measures of longevity indicate this species may live for up to 20 years. At maturation, males normally mate every year, while female reproductive activity is usually restricted to a single year between periods of sexual inactivity. Thus numbers of sexually active females may vary greatly depending on locality and year (Souty-Grosset et al. 2006).
Studies have shown (Jensen 1996) that this species of crayfish is particularly susceptible to increased levels of nitrite in aquatic systems, meaning input of excess amounts of this compound, particularly through agricultural fertilizer run-off, may pose a serious risk to this species.
It is known that noble crayfish females reach sexual maturity at a size which ranges from 6.2 cm total length in localities with early maturity or slow growth to 8.5 cm total length in localities with late maturity or fast growth. Males become mature at a size of 6.0-7.0 cm total length (Skurdal & Taugbøl 2002).
Declines in this keystone species are said to negatively impact both ecosystem structure and function within freshwater environments through loss of: a) provisioning services – food production from fisheries, recreational fishing, b) regulatory and support services – trophic cascades, water purification, nutrient cycling, primary productivity, c) cultural value – recreational fishing, education, heritage. Crayfish are also an important food source to a range of species including otters, salmonids, and birds such as kingfishers (Kettunen and ten Brink 2006).
- Заморока А.М., Бідичак Р.М., Геряк Ю.М., Глотов С.В., Капрусь І.Я., Козоріз Ю.Г., Мартинов О.В., Михайлюк-Заморока О.В., Пушкар Т.І., Різун В.Б., Слободян О.М., Смірнов Н.А., Утєвський С.Ю., Шпарик В.Ю. Розповсюдження рідкісних видів безхребетних тварин, занесених до Червоної книги України, в Івано-Франківській області // Український ентомологічний журнал. – 2017. – 2(13). – С.77-94.