Noble Crayfish

The Noble Crayfish is referenced in fishery legislation. This species is found in rivers, lakes,ponds, and reservoirs, in both lowlands  and hills, where shelter availability is high. 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. This species is capable of tolerating lower calcium levels, as low as 2-3 mgl-1Ca, where other species of crayfish may be excluded. The optimum temperature for best growth is between 16 and 24⁰C, although temperatures up to 28⁰C can generally be tolerated. In addition, oxygen content below 3-4 mgl-1is deemed unsuitable for this species. Some 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. Studies have shown 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 6-7 cm total length. 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, Liechtenstein, Luxembourg, Morocco, the UK, and possibly Montenegro and Italy, is via introductions from neighboring countries. In Prespa, due to its low population density, at present it is forbidden for catching (fishing).