A Comparison of Survival and Growth in Juvenile Astacus Leptodactylus (Esch.) and Pacifastacus Leniusculus (Dana) Under Controlled Conditions

Abstract

The aim of this study was to compare survival and growth of juvenile narrow-clawed crayfish (Astacus leptodactylus) and signal crayfish (Pacifastacus leniusculus) fed only with experimental pellets (45% of proteins, 6% of fat, 20% crude fibre) under controlled conditions. The animals were reared in 12 (50 l) circular plastic tanks, the narrow-clawed crayfish set-ups being designated A1 and A2, the signal crayfish set-ups P1 and P2. The initial stocking densities for each species were 600 (A1, P1) and 1,200 (A2, P2) juveniles stage 2 per square metre for each set-up in three replicates. The experiment lasted 92 days under continuous photoperiod (L:D 24:0; 100 LUX) conditions at a temperature of 22.0 ± 0.1°C and an oxygen saturation > 90%. One shelter (plastic tube) was provided for 2 crayfish in each set-up.The highest survival rate was obtained for signal crayfish from set-up P1 (47.5%), the lowest for narrow-clawed crayfish from set-up A2 (22.8%). Crayfish survival evidently depends on the stocking density: in set-ups A1 and P1 it was about 16% higher than in set-ups A2 and P2 (P < 0.05). Mortality was significantly higher (P < 0.05) in both species during the first 30 days of the experiment (48-77% of the total mortality) than during the subsequent two months of the experiment (< 20% of the total mortality).The final body size was the largest in narrow-clawed crayfish from set-up A1 (799 mg, 29.2 mm) and the smallest in signal crayfish from set-up P2 (534 mg, 26.5 mm). Specimens of narrow-clawed crayfish were larger than signal crayfish, and the specimens of both species in set-ups A1 and P1 were larger than those in set-ups A2 and P2. During the first 30 days of the experiment the specific growth rate (SGR) of both species in all set-ups was twice the value reported during the subsequent two months (P < 0.05). La survie des écrevisses dépend évidemment de la densité de départ: dans les lots A1 et P1, la survie est supérieure de 16 % par rapport à celle des lots A2 et P2 (P < 0,05). La mortalité a été significativement plus importante (P < 0,05) pendant les 30 premiers jours de l'expérience (48-77 % de la mortalité totale) que pendant les deux derniers mois (< 20 % de la mortalité totale). Key-words:Les écrevisses à pattes grêles du lot A1 ont présenté les tailles corporelles les plus grandes (799 mg ; 29,2 mm) alors que les plus petites ont été enregistrées dans le lot P2 (534 mg ; 26,5 mm). D'une façon générale, les écrevisses à pattes grêles étaient plus grandes que les écrevisses signal et les individus des lots A1 et P1 étaient aussi plus grands que ceux des lots A2 et P2. Pendant les 30 premiers jours de l'expérience, le taux de croissance spécifique (SGR) de chaque espèce (A1, A2, P1, P2) était plus important que celui mesuré dans les deux mois suivants (P < 0,05).

A comparison of the growth and survival of two freshwater crayfish species, Astacus leptodactylus Eschscholtz and Pacifastacus leniusculus (Dana), under different temperature and density regimes

“…4 for P. leniusculus). Ulikowski et al (2006) reported similar observations with older individuals of both species after 6 months of rearing. Therefore, Ulikowski et al (2006) concluded that the growth rate of A. leptodactylus under optimal conditions is comparable to that of P. leniusculus.…”

“…Therefore, it can be concluded that the juveniles of both species have similar growth rates. Ulikowski et al (2006) also found a similar growth rate in P. leniusculus and A. leptodactylus during the first 3 months after hatchings. The SGR was 1.3 (initial density: 600 stage 2 m -2 ) and 1.4 (initial density: 1,200 stage 2 m -2 ) for A. leptodactylus and 1.7 for P. leniusculus (at both densities).…”

“…The SGR was 1.3 (initial density: 600 stage 2 m -2 ) and 1.4 (initial density: 1,200 stage 2 m -2 ) for A. leptodactylus and 1.7 for P. leniusculus (at both densities). However, Ulikowski et al (2006) pointed out that the SGR in all set-ups of their experiments were twofold higher during the first 30 days than during the following 2 months. As was observed in the first experiment of this study, Ulikowski et al (2006) also found that the juveniles of A. leptodactylus grew faster than those of P. leniusculus during the first month of their experiment (SGR was 6.4 and 5.8 for A. leptodactylus, and 5.6 and 5.…”

The spiny-cheek crayfish Orconectes limosus (Rafinesque, 1817) as an inhabitant of the Baltic Sea — experimental evidences for its invasion of brackish waters

“…Our results from brackish water corroborate this statement. The survival of juveniles may be affected by the insufficient number of shelters (Figler et al 1999), higher molting frequency (Barki et al 1997) and high density promoting cannibalism (Ulikowski et al 2006). Young crayfish are very sensitive organisms (Świerczyński 2000).…”

Additional supply of decapsulatedArtemiacysts for various periods in intensive rearing of juvenile crayfish (Pacifastacus leniusculus, Astacidae)

“…Among them, several trials have shown that the supply of dry diets as the sole food from the onset of exogenous feeding yields poor survival or growth rates (e.g. Ackefors et al, 1989;Taugbøl and Skurdal, 1992;Celada et al, 1993;Ulikowski et al, 2006;Sáez-Royuela et al, 2007). Recently, acceptable survival and growth rates were recorded by means of the additional supply of live Artemia nauplii to a commercial dry diet for salmonids (Sáez-Royuela et al, 2007;González et al, 2008), thus allowing for the first time reliable possibilities of intensification.…”