Growth, mortality and moulting rate of noble crayfish, Astacus astacus L., juveniles in aquaculture experiments

Abstract

Growth, mortality, moulting rate and cheliped loss were examined in aquaculture experiments with noble crayfish, Astacus astacus L., juveniles from four different Norwegian populations in the period September 1987‐June 1988. The juveniles were hatched indoors in May 1987 from parents wild‐caught in 1986. The experiments were performed at 18‐19°C in communal rearing units. Mean total length at experiment start was about 20mm in all groups. There were no significant differences in mean size (final mean total length: 32‐2‐34‐8mm). mortality (83a‐900%) or cheliped loss (429‐700%) among juveniles from the different populations when exposed to similar conditions (food: dry pellets; photoperiod: L:D = 8:16). Among crayfish fed fish and potatoes in addition to dry pellets, and with continuous light conditions, mortality was reduced significantly to about 70%. Continuous light conditions significantly increased mean size (final mean length: 36‐1‐389mm). Moulting occurred from November throughout the experiment period. Moulting rate was positively correlated to mortality and growth rate (i.e. mean length increase). A positive correlation between mortality and cheliped loss, along with direct observations of cannibalism, indicated that agonistic behaviour and cannibalism were the dominating mortality factors. It is suggested that continuous light conditions reduce agonistic behaviour and thereby decrease mortality.

Stocking density for the intensive rearing of juvenile crayfish, Pacifastacus leniusculus (Astacidae), using Artemia nauplii to supplement a dry diet from the onset of exogenous feeding

“…Several authors have carried out experiments with astacid crayfish at initial concentrations between 50 and 200 stage 2 juveniles per m 2 under controlled conditions but focussed on productive factors other than density (Mason 1979;D'Abramo et al 1985;Ackefors et al 1989;Gydemo and Westin 1989;Celada et al 1989Celada et al , 1993Taugbøl and Skurdal 1992;Ackefors et al 1992Ackefors et al , 1995Henttonen et al 1993;Blake et al 1994;Sáez-Royuela et al 1995, 1996, 2001Savolainen et al 2003). The studies of Ackefors et al (1989), Nyström (1994) and Savolainen et al (2004) have focussed on density effects.…”

“…Fresh Daphnia, earthworms, chironomid larvae, Chlorella, fresh fish, vegetables and experimental dry pellets for crayfish and for fish species have been tried by Mason (1979), D'Abramo et al (1985), Celada et al (1989Celada et al ( , 1993, Blake et al (1994), Sáez-Royuela et al (1995, 1996 and Savolainen et al (2003Savolainen et al ( , 2004 with Pacifastacus leniusculus. Gydemo and Westin (1989), Ackefors et al (1989Ackefors et al ( , 1992Ackefors et al ( , 1995, Taugbøl and Skurdal (1992) and Henttonen et al (1993) used different combinations of frozen fish and vegetables, oat flakes, Chara, frozen insect larvae and Neomysis, fresh Mysis and formulated feedstuffs for other crustaceans with Astacus astacus, whereas Sáez-Royuela et al (2001) tested fresh Daphnia and a feed formulated for rainbow trout with Austropotamobius pallipes. In all of these cases, after exceeding the critical period of the first 2-3 months and leaving aside the high mortalities sometimes recorded, survival rates were about 50% with growth values of 8-12 mm carapace length and 90-200 mg in a temperature range of 18-22°C.…”

Habitat Preference of Different Size Classes of Austropotamobius Pallipes in an Irish River

“…Aggressive behaviour is a major constraint in communal rearing systems, used for commercial or restocking purposes (MATTHEWS, 1992;SÁEZ-ROYUELA et al, 1995). Moulting in juveniles is less synchronised than in adults (LOWERY, 1988;TAUGBØL and SKURDAL, 1992;SÁEZ-ROYUELA et al, 2001), which would make small crayfish even more susceptible to predation from conspecifics and stresses the need for suitable shelter.…”

Interaction between juvenile narrow-claw crayfish, Astacus leptodactylus (Eschscholtz), and common water frog, Rana esculenta (L.), tadpoles or common blue damselfly, Enallagma cyathigerum (Charpentier), larvae during rearing under controlled conditions

“…After a subsequent fifteen or so days, the young leave the mother and begin to live independently (Kossakowski 1966). The first period of crayfish life is marked by high mortality caused by many factors including predation, cannibalism, and environmental conditions (Taugbrl andSkurdal 1992, Ulikowski andKrzywosz 2006). The greatest threats posed to both juvenile and older crayfish are doubtlessly predatory bottom-feeding fish such as perch, Perca fluviatilis L., wels catfish, Silurus glanis L., burbot, Lota lota (L.), and European eel, Anguilla anguilla (L.) (Svensson 1993, Czerniejewski andTañski 2001).…”