Stocking density affects the growth, survival, and cheliped injuries of third instars of narrow-clawed crayfish, Astacus leptodactylus Eschscholtz, 1823 juveniles
2007; Brill; Volume: 80; Issue: 7 Linguagem: Inglês
10.1163/156854007781363114
ISSN1568-5403
Autores Tópico(s)Aquaculture Nutrition and Growth
Resumo[The effect of stocking density on the growth and survival of Astacus leptodactylus juveniles was evaluated. Newly hatched third instars of A. leptodactylus with an average total length of 11.4 mm (TL) and an average weight of 22.4 mg were stocked in 0.14 m 2 tanks in a recirculation system at 50, 100, and 200 specimens/m 2 and reared for 120 days at 22.8°C. Crayfish growth was inversely correlated with density. The mean final weights for the crayfish were 1.26, 1.16, and 0.91 g for crayfish densities of 50, 100, and 200/m 2 , respectively. Survival of the crayfish was also affected by stocking density; it decreased as initial stocking density increased. The proportion of lost chelipeds was also found to be dependent on the stocking density and increased with increasing stocking density. The differences in the proportion of crayfish with cheliped injuries among animals stocked at 50/m 2 , 100/m 2 , and 200/m 2 were found to be 7.1%, 16%, and 29%, respectively. The yield was directly related to density ( P 2 = 0.95). No evidence was found for feed conversion ratio (FCR) being affected by density. Astacus leptodactylus had a normal length distribution of 11-12 mm at the beginning of the experiment. However, at the end of the experiment, the length distribution varied among animals in the three density treatments. At the densities of 100/m 2 and 200/m 2 , animals had a final length range of 16-40 mm TL, showing a distinct peak at 21-25 mm TL; however, at the density of 50/m 2 , the animals had a final length range of 16-41 mm TL with a distinct peak at 26-30 mm TL. In addition, the implications of the above findings for optimal intensive culture conditions for juvenile Astacus leptodactylus are discussed. L'effet de la densite de stockage sur la croissance et la survie des juveniles d' Astacus leptodactylus a ete evalue. Des troisiemes stades nouvellement eclos d' A. leptodactylus d'une longueur totale moyenne de 11,4 mm (TL) et d'un poids moyen de 22,4 mg ont ete stockes dans des bacs de 0,14 m 2 pourvus d'un systeme de recirculation, a des densites de 50, 100 et 200 specimens/m 2 et eleves pendant 120 jours a 22,8°C. La croissance des ecrevisses etait inversement correlee a la densite. Les poids moyens finaux des ecrevisses etaient de 1,26, 1,16 et 0,91 g a des densites de 50, 100 et 200/m 2 , respectivement. La survie etait egalement affectee par la densite de stockage; elle diminuait avec l'augmentation de la densite initiale de stockage. La proportion de chelipedes perdus dependait egalement de la densite de stockage et augmentait en meme temps que la densite de stockage. La difference dans la proportion d'ecrevisses ayant des blessures aux chelipedes par rapport aux animaux stockes a 50/m 2 , 100m 2 et 200/m 2 etait de 7,1%, 16% et 29%, respectivement. Le rendement etait en relation directe avec la densite ( P 2 = 0,95). Il n'a pas ete mis en evidence que le rapport de conversion de la nourriture (FCR) soit affecte par la densite. Au debut de l'experimentation, Astacus leptodactylus presentait une distribution de longueur normale de 11-12 mm. Cependant, a la fin de l'experimentation, la distribution de longueur variait dans les trois densites testees. Aux densites de 100/m 2 et 200/m 2 , les animaux avaient, a la fin de l'experimentation, une longueur de 16-40 mm TL, avec un pic net a 21-25 mm TL; mais, a la densite de 50/m 2 , leur longueur finale etait de 16-41 mm TL, avec un pic net a 26-30 mm TL. Les implications de ces resultats pour determiner les conditions optimales de culture intensive des juveniles d' Astacus leptodactylus sont discutees. , The effect of stocking density on the growth and survival of Astacus leptodactylus juveniles was evaluated. Newly hatched third instars of A. leptodactylus with an average total length of 11.4 mm (TL) and an average weight of 22.4 mg were stocked in 0.14 m 2 tanks in a recirculation system at 50, 100, and 200 specimens/m 2 and reared for 120 days at 22.8°C. Crayfish growth was inversely correlated with density. The mean final weights for the crayfish were 1.26, 1.16, and 0.91 g for crayfish densities of 50, 100, and 200/m 2 , respectively. Survival of the crayfish was also affected by stocking density; it decreased as initial stocking density increased. The proportion of lost chelipeds was also found to be dependent on the stocking density and increased with increasing stocking density. The differences in the proportion of crayfish with cheliped injuries among animals stocked at 50/m 2 , 100/m 2 , and 200/m 2 were found to be 7.1%, 16%, and 29%, respectively. The yield was directly related to density ( P 2 = 0.95). No evidence was found for feed conversion ratio (FCR) being affected by density. Astacus leptodactylus had a normal length distribution of 11-12 mm at the beginning of the experiment. However, at the end of the experiment, the length distribution varied among animals in the three density treatments. At the densities of 100/m 2 and 200/m 2 , animals had a final length range of 16-40 mm TL, showing a distinct peak at 21-25 mm TL; however, at the density of 50/m 2 , the animals had a final length range of 16-41 mm TL with a distinct peak at 26-30 mm TL. In addition, the implications of the above findings for optimal intensive culture conditions for juvenile Astacus leptodactylus are discussed. L'effet de la densite de stockage sur la croissance et la survie des juveniles d' Astacus leptodactylus a ete evalue. Des troisiemes stades nouvellement eclos d' A. leptodactylus d'une longueur totale moyenne de 11,4 mm (TL) et d'un poids moyen de 22,4 mg ont ete stockes dans des bacs de 0,14 m 2 pourvus d'un systeme de recirculation, a des densites de 50, 100 et 200 specimens/m 2 et eleves pendant 120 jours a 22,8°C. La croissance des ecrevisses etait inversement correlee a la densite. Les poids moyens finaux des ecrevisses etaient de 1,26, 1,16 et 0,91 g a des densites de 50, 100 et 200/m 2 , respectivement. La survie etait egalement affectee par la densite de stockage; elle diminuait avec l'augmentation de la densite initiale de stockage. La proportion de chelipedes perdus dependait egalement de la densite de stockage et augmentait en meme temps que la densite de stockage. La difference dans la proportion d'ecrevisses ayant des blessures aux chelipedes par rapport aux animaux stockes a 50/m 2 , 100m 2 et 200/m 2 etait de 7,1%, 16% et 29%, respectivement. Le rendement etait en relation directe avec la densite ( P 2 = 0,95). Il n'a pas ete mis en evidence que le rapport de conversion de la nourriture (FCR) soit affecte par la densite. Au debut de l'experimentation, Astacus leptodactylus presentait une distribution de longueur normale de 11-12 mm. Cependant, a la fin de l'experimentation, la distribution de longueur variait dans les trois densites testees. Aux densites de 100/m 2 et 200/m 2 , les animaux avaient, a la fin de l'experimentation, une longueur de 16-40 mm TL, avec un pic net a 21-25 mm TL; mais, a la densite de 50/m 2 , leur longueur finale etait de 16-41 mm TL, avec un pic net a 26-30 mm TL. Les implications de ces resultats pour determiner les conditions optimales de culture intensive des juveniles d' Astacus leptodactylus sont discutees. ]
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