Reproductive efficiency of the narrow-clawed crayfish, Astacus leptodactylus, in several populations in Turkey

• Published in: Crustaceana 2009-01, Vol.82 (5), p.531-542
• Main Authors: Berber, Selçuk, Mazlum, Yavuz
• Format: Article
• Language: English
• Subjects: Astacus leptodactylus; Cambaridae; Crayfish; Egg weight; Eggs; Fecundity; Female animals; Fresh water; Freshwater; Lakes; Leptodactylus; Mene; Ova; Turkeys; Water temperature
• ISSN: 0011-216X; 1568-5403
• DOI: 10.1163/156854009X407713

Studies were carried out to evaluate the reproductive efficiency of the narrow-clawed crayfish, Astacus leptodactylus Eschscholtz, 1823, in three different populations in the lakes Apolyont, Iznik, and Manyas in Turkey. Crayfish were sampled monthly using fyke-nets of 34 mm mesh size from April 2002 until March 2003. The average number of pleopodal eggs (with their range), per female, was 200 ± 12 (8-556) in Lake Apolyont, 202 ± 13 (6-350) in Lake Iznik, and 257 ± 13 (18-465) in Lake Manyas. The average number of ovarian eggs (with their range), per female, was 348 ± 20 (126-630) in Lake Apolyont, 305 ± 11 (162-465) in Lake Iznik, and 400 ± 18 (205-776) in Lake Manyas. The average egg diameter and ranges were 2.23 ± 0.004 (1.80-2.98) mm in Lake Apolyont, 2.53 ± 0.003 (2.06-2.92) mm in Lake Iznik, and 2.65 ± 0.027 (1.98-3.04) mm in Lake Manyas. Neither egg diameter nor egg weight increased with body size, but the variability of egg size and weight was high. No relationship was found between egg size and female crayfish size for any of the lakes. Mean size at maturity of female A. leptodactylus varied among the lakes. Females in Apolyont populations reached sexual maturity at a size of 64.3 mm TL, but spawning occurred only when females attained 82-128 mm TL, indicating that the mean minimum reproductive size was 82 mm TL in Lake Apolyont. Average female size was 88.7 mm (±SD 0.6; max. 142 mm; min. 48 mm; n = 154). In Iznik Lake, size at maturity of females was 78 mm TL, while spawning size was 83-142 mm TL; average female size was 90.6 mm (±SD 0.5; max. 139 mm; min. 66 mm; n = 99). Finally, female size at maturity was 72.6 mm TL, and spawning size was 80-130 mm TL in Manyas Lake; average female size was 89.0 mm (±SD 1.1; max. 141 mm; min. 29 mm; n = 122). The total observed sex ratio (male/female) was found to be 1.00/0.53 in all three lakes together. Mature A. leptodactylus reproduce only once a year under natural conditions. No evidence was found in this study to suggest the occurrence of multiple spawnings. /// Des études pour évaluer l'efficacité reproductrice de l'écrevisse à pattes grêles Astacus leptodactylus Eschscholtz, 1823, ont été menées dans trois différentes populations dans les lacs Apolyont, Iznik, et Manyas en Turquie. Les écrevisses ont été échantillonnées mensuellement en utilisant un filet verveux à ailes de maille de 34 mm d'avril 2002 à mars 2003. Le nombre moyen d'œufs sur les pléopodes par femelle était de 200 ± 12 (8-556) dans le la