The Noble Crayfish (Astacus astacus) is a widespread species, it has undergone significant declines in population numbers due to non-indigenous species, crayfish plague, habitat loss and over-harvesting. Estimates of rate of decline in Sweden, Finland and Norway are as high as 78%, ~20% and 61% respectively over a 3 generation length period. Similar rates of decline are being seen within a number of other countries. Globally, this species is estimated to be declining at a rate of 50-70%, however in some parts of its range numbers are stable and there have been some successful re-stocking programs so the true rate of decline may in fact be slightly lower (40 - 50%) thereby qualifying this species for a listing under Vulnerable under criterion A2ad.

• 1996 – Vulnerable (VU)
  Download assessment
• 1994 – Vulnerable (V)
  Download assessment
• 1990 – Vulnerable (V)
  Download assessment
• 1988 – Vulnerable (V)
  Download assessment
• 1986 – Vulnerable (V)
  Download assessment
• 1983 – Vulnerable (V)
  Download assessment

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).

Andorra: There are currently three known subpopulations at an elevation range of 800-1,000 m above sea level (T. Changeux pers. comm. 2001 cited in Holdich 2002). The presence of this species within Andorra is doubted and is thought to in fact be Austropotamobius fulcisianus (a soon to be described species) which resulted from introductions from Spain or France (Y. Machino pers. comm. 2009). This species is known from 115 sites, 71 of which are ponds (Collas et al. 2007). There is a continual loss of natural populations: many occurrences are due to introductions (C. Souty-Grosset pers. comm. 2010).

Austria: Historical records of the Noble Crayfish in Austria data back to 1321 and indicate yields of up to 10 kg ha-1yr-1 in some lakes (Pöckl 1999).  Outbreaks of crayfish plague were first recorded in Austria in 1878, and between 1879 and 1904, approximately 75% of Noble Crayfish subpopulations were devastated (Pöckl 1999). Although the Noble Crayfish is still widespread throughout Austria, most subpopulations are considered unstable and stocks in major rivers have been reduced (Pöckl 1999, Füreder and Souty-Grosset 2005). Often, only single specimens can be found during sampling (Pöckl 1999). 

Belgium: This species is now extirpated from Flanders, but can still be found in Wallonia. Over the last decade, the Noble Crayfish has disappeared from approximately 20% of the sites from which it was previously known (R. Cammaerts pers. comm. 2008). Arrignon et al. (1999) have reported a 67% reduction in this species between 1989 and 1999.

Bulgaria: This species is economically important but population numbers are significantly diminished (Zaikov and Hubenova 2007). This is attributed to inefficient management of the wild fisheries.

Belarus: Population numbers of this species are thought to be on the increase as it spreads up small rivers (Kulesh et al. 1999). It is currently known from 32 water bodies.

Bosnia: There is no available up to date information on this species within Bosnia. The last report of this species comes from a single locality in Tuzla by Entz in 1909.

Croatia: Subpopulations of this species within Croatia appear to be relatively stable at present, although non-native crayfish species (including carriers of crayfish plague) have only been recently introduced to this area (I. Maguire and G. Klobučar pers. comm. 2008).  Future declines are expected.

Czech Republic: There is also an apparent decline in Noble Crayfish numbers in the Czech Republic, with only one third of recorded localities from the 1980s being confirmed during more recent surveys. However, these studies have also identified a number of new localities, not previously surveyed (E. Kozubikova, P. Kozak and A. Petrusek pers. comm. 2008). This is the most common crayfish species in the Czech Republic.

Denmark: This species is known from the Jutland Peninsula and the islands of Zealand and Funen, though its range is in decline due to habitat degradation (Skurdal et al. 1999). The status of the Danish subpopulation is currently unknown as no attempt, as of yet, has been made to document the crayfish species, distribution and abundance (S. Berg pers. comm. 2008).

Estonia: This species is the only crayfish species present within this country, and is widespread. Declines in the population numbers and range of this species have been noted (Skurdal et al. 1999). However attempts are being made to reintroduce this species into former areas of its range through translocations and hatchery reared juveniles (Skurdal et al. 1999).

Finland: Astacus astacus population is at a very low level compared to historical (pre-1900) levels. The current rate of the decline of the separate A. astacus populations is low (probably less than 5 % per 20 years), but the decline of the A. astacus population size in the whole country is continually declining 20 % or even more every 20 years (M. Pursiainen pers. comm. 2010).

France: This species is said to be close to extinction in Lorraine and Morvan, however restocking has been attempted. It is also present within other regions of France, including Alsace. In south and southwestern France it has been extending its range, it is an introduced species (Y. Machino pers. comm. 2009).

Georgia: There does not appear to be any recent accounts of this species within Georgia.

Germany: This species was once widespread and abundant throughout Germany, but over the last century it has become restricted to more upland regions due to habitat degradation, competition, predation and disease (Schulz 2000). In the district of Lower Saxony in northwest Germany, this species was reported from 155 sites in 1920 (after the introduction of crayfish plague), but by 1990 it was only present at 12 sites (Schulz 2000), a decline in range of 56% over a period of 22.5 years.

Greece: The distribution of the Noble Crayfish in Greece is now much more restricted and fragmented than in previous decades (Koutrakis et al. 2007).

Hungary: The Noble Crayfish is the most widespread crayfish species within Hungary, and certainly the most common within northern regions (Puky et al. 2005). Data from the commercial harvest of A. astacus indicate that there has been a decline in the abundance of approximately 95% over the last 22.5 years, from an annual catch of 13,000 kg for export in 1961 and only 1,000 kg in 1980 (Puky et al. 2005). This species is still considered to be declining owing to habitat degradation and loss, and crayfish plague (Puky and Schád 2006). 

Latvia: There are little available data on the current status of the population within Latvia. It is known to be widespread (T. Taugbøl pers. comm. cited in Holdich 2002).

Lithuania: In 2008, a study to look at sites from which this species was previously known found this species at three of six rivers (only one of these three rivers in fact had an abundant populations, while the others contained Orconectes limosus). Out of 14 lakes that were looked at, only nine contained this species (seven lakes were estimated as having quite abundant populations) and five lakes were devoid of Astacus (though two of these have been reported to contain crayfish by local people). The conclusion is, despite healthy A. astacus populations still being present, there is a decline in the abundance of this species as a result of the invasive species Orconectes limosus (K. Arbaciauskas pers. comm. 2010).

Macedonia: This species is known from the Vardar drainage system as well as from the Ohrid Lake - Drin drainage system (Y. Machino pers. comm. 2009). Within Lake Ohrid this species is showing a steep decline in population numbers possibly as a result of pollution (Y. Machino pers. comm. 2009). Austropotamobius torrentium is already thought to have gone extinct in a tributary of Lake Ohrid (Koselska Brook) below Reica as a result of pollution (Y. Machino pers. comm. 2009). 

Moldova: There are no available data on the current population trends for this species within Moldova.

Montenegro: It is the opinion of Y. Machino that Astacus astacus is native in the Danubian drainage. Then on the Mediterranean side, it is exotic, and people have introduced with success.

Netherlands: This species is indigenous to the Netherlands, however it is thought to be close to extinction. Surveys of this species presence/absence in rivers and brooks throughout the Netherlands, indicate a rapid decline with it being known from a single river in 2001 (Niewold 2002). Prior to 1920 it was known from 44 localities, 1921 - 1940 = 32 localities, 1941 - 1960 = 28 localities, 1961 - 1980 = 15 localities, 1981 - 2000 = 4 localities, and in 2001 = one locality (Niewold 2002). Over the last 22.5 years this equates to a decline of ~86%.

Norway: The Noble Crayfish, the only crayfish species in Norway, has undergone significant declines since the introduction of crayfish plague in the late 1970s to the Glomma, Halden, Veksa and Store Le watercourses (Taugbøl 2004). Since the late 1980s there have been reintroductions of crayfish adults and juveniles into both the Glomma and Halden watercourses. These subpopulations are developing at varying rates (site habitat characteristics are thought to be largely responsible) however population densities are still significantly below pre-plague densities (Taugbøl 2004). This species has also been reintroduced to the Veksa watercourse. This is believed to have been as a result of fishermen, however the population is much reduced compared to pre-plague densities (Taugbøl 2004). This is thought to be due to declining water quality conditions (Taugbøl 2004). This species is estimated to have undergone  ~61% decline over the last 22.5 years from a 40 tonnes yield in 1966, to 10 tonnes in 1999 (Skurdal et al. 1999). However, in Lake Steinsfjorden in south east Norway, CPUE (individuals per trap night) data indicates a recent increase in abundance, though there are no recent data for the period 2000 to present (1979 - 1.1; 1980 - 1.1; 1981 - 0.8; 1982 - 0.8; 1983 - 1.3; 1984 - 1.4; 1985 - 1.3; 1985 - 1.3; 1986 - 1.3; 1987 - 0.7; 1988 - 0.6; 1989 - 0.5; 1990 - 0.7; 1991 - 0.8; 1992 - 0.6; 1993 - 0.9; 1994 - 0.7; 1995 - 0.6; 1996 - 0.5; 1997 - 0.6; 1998 - 0.9; 1999 - 1.0; 2000 - 1.0). This lake is the most important crayfish locality in Norway and accounts for approximately 25% of the annual harvest (Taugbøl and Eriksen 1991, Skurdal, G årnas and Taugbøl 2002).

Poland: This species is widespread within Poland, but is in decline. Approximately one subpopulation is lost every two years (1998 - 98 subpopulations, 2008 - 89 subpopulations) as a result of the introduced species Orconectes limosus Spiny-cheek Crayfish. The range expansion of this introduced species is attributed to the growing tourism industry within Poland, and hence growing interest in angling. Anglers are said to be responsible for moving this species around as it is often taken for bait (P. Smietana pers. comm. 2009). Other possible reasons for these declines may also be due crayfish plague and pollution (P. Smietana pers. comm. 2009). Restocking of this species in former parts of its range is underway. New subpopulations are also still being discovered, although numbers are low. These subpopulations are thought two have always existed, but have only recently been discovered due to the expansion in survey area (P. Smietana pers. comm. 2009). The listing of Vulnerable in the Polish Red Data Book is thought to be suitable to the current situation (P. Smietana pers. comm. 2009).

Romania: This species is known from the Carpathian region and an area in the north east of Romania, however it is possible that it is in fact more widespread (L. Miron pers. comm. 2008). Moderate declines in this species have been observed in Romania (L. Miron pers. comm. 2008).

Russian Federation: This species is widespread within Russia, although it is declining in areas of its range. This species is known from Vologda district, Novgorod district, Kaliningrad district, Pskov district and Leningrad district (Fedotov, Bykadorova and Kholodkevich 1998). The population status is not known within Vologda district, however it is said to be found within most lakes and rivers. It is occasionally taken as by-catch by fishers, but is not sold in markets (Fedotov, Bykadorova and Kholodkevich 1998). Kaliningrad is a small district within Russia with a very high population density. The water bodies are said to be badly polluted (Fedotov, Bykadorova and Kholodkevich 1998). This species is now absent from a large number of the water bodies in which it was previously found. The Pskov district is said to have a lot of suitable habitat for this species and produces an annual catch of 10,980 kg (Perminov 1995).

Serbia: This species was once found all over Serbia but now is only known from a few very restricted localities (Simic et al. 2008, Y. Machino pers. comm. 2009).

Slovenia: This species is native to Slovenia and is found in the Danube River basin, however subpopulations in the northeast of the country have been introduced (Budhina 1989).

Slovakia: This species is thought to be the most abundant crayfish throughout Slovakia (P. Manko pers. comm. 2008). It occurs within eastern and northern Slovakia. Subpopulations are thought to be currently stable (P. Manko pers. comm. 2008).

Sweden: It is estimated that at the beginning of the 20th century, there were some 30,000 subpopulations of this species in Sweden alone (Bohman et al. 2006).  However, by 1960, only 50% of these remained (Bohman et al. 2006).  In 1994, just 1,724 subpopulations were recorded and numbers continued to decline to 1,597 subpopulations by 1997 and approximately 1,000 subpopulations in 2002 (Bohman et al. 2006). It is estimated that the current rate of crayfish plague outbreaks has increased by 90% (L. Edsman pers. comm. 2008). Over the last 22.5 years there has been an estimated decline of ~78% based on a decline from 1,724 known subpopulations in 1994, to 1,000 subpopulations in 2002 (Fiskeriverket and Naturvårdsverket 1998; Database of Crayfish Occurrences 2005). However, this country still has one of the largest capture fisheries (Souty-Grosset et al. 2006). This species is now regarded as Critically Endangered in the new 2010 Red List of Swedish Species (It was Endangered in the red list from 2005). This is based on the heavy decline but also on the fact that the crayfish plague has increased 10 fold in the last few years and the disease has now spread to parts of the country that still had Noble Crayfish (the north and middle west parts of the country) and never had crayfish plague before. This is due to illegal introductions of the introduced plague carrying signal crayfish. The species is more or less gone from lakes and rivers in the south and middle east parts of the country where the best habitats are climate wise and the best possibilities for good noble crayfish populations (Edsman and Schröder 2009, Gärdenfors 2010).

Switzerland: Within Switzerland this species is considered to be in a state of decline largely due to Aphanomyces astaci and is considered to be 'threatened' or 'endangered' by the Swiss National Legislation on Fisheries (D. Hefti pers. comm. 2008, Füreder & Souty-Grosset 2005). 

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 24^oC, although up to 28^oC 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).

In Sweden, this species is estimated to have undergone a decline of ~78% over the last 22.5 years based on a decline from 1,724 known subpopulations in 1994, to 1,000 subpopulations in 2002 (Fiskeriverket and Naturvårdsverket 1998; Database of Crayfish Occurrences 2005). In Finland, the rate of decline is currently at about 20% every 20 years, though it may be greater (M. Pursiainen pers. comm. 2010). In Norway, this species is estimated to have undergone  ~61% decline over the last 22.5 years from a 40 tonnes yield in 1966, to 10 tonnes in 1999 (Skurdal et al. 1999). While there is no available quantifiable data on the trends in Denmark, the situation is likely to be similar. Rates of decline in other countries are similar to that of the Scandinavian countries: ~67% decline over 10 years in Belgium (Arrignon et al. 1999), ~56% decline in Germany over 22.5 years, ~95% decline over 22.5 years in Hungary, and ~86% decline in the Netherlands over 22.5 years. Notable declines are reported for most of the other countries, other than Belarus where numbers are said to be increasing; Croatia where numbers are stable but non-native species have recently been introduced so future declines are expected;  Slovakia where numbers are thought to be stable. These figures indicate that this species is likely undergoing a rate of decline of around 50-80% over a 22.5 year period. However, there are a number of large-scale re-stocking programs for this species and in some areas of its range, numbers are stable so the true rate of decline is likely closer to 30-50% globally.