An investigation on the population parameters of freshwater crayfish(Astacus leptodactylus Esch., 1823) in Lake İznik (Bursa)

Abstract

Although crayfish are not much consumed in Turkey, fishing of the freshwater crayfish, which are especially sought after in European countries, started in lakes Manyas and Apolyont (Uluabat) at the beginning of 1965. It gained importance with its increasing export volume (Berber and Balık, 2006). Statistics for the number of freshwater crayfish caught in Turkish inland waters were not routinely recorded until 1976, and the number of freshwater crayfish caught was given as 3.885 t for the first time in 1977 (TÜİK, 1976(TÜİK, -1979. Isparta and Bursa were the leading provinces catching freshwater crayfish in those years.Lake İznik is situated within the borders of the province of Bursa in the Marmara region. The lake, with a surface area of approximately 313 km 2 , has a maximum depth of 65 m and its elevation above sea level is 85 m. The length of the lake is approximately 32 km and the widest point is 12 km. It is the largest natural lake in the Marmara region and the fifth largest in Turkey. There are five streams and ground waters that feed the lake (Aktan and Aykulu, 2001). Lake İznik, which is eutrophic in terms of ecology, is quite rich in diversity of species of fish compared with many other lakes; apart from the crayfish, there are 19 species of fish in the lake (Özuluğ et al., 2005).After the occurrence of crayfish plague in Turkish inland waters, crayfish stocks in lakes İznik and Apolyont were also negatively affected, and commercial crayfish

Predata on Some Morphometric Characters and Condition Factors of Crayfish, Astacus leptodactylus (Eschscholtz, 1823) from Kılıçkaya Reservoir, Sivas, Turkey

“…The mean value of condition factor for all individuals in the present study was found to be 2.58±0.29 which being very close to unity, indicates that the A. leptodactylus is in good condition. Similarly, Aydın et al [14] recorded a mean condition factor value of 2.6 for A. leptodactylus in İznik Lake. Also, Kaya [22] reported the value of the mean condition factor to be 3.31 for A. leptodactylus in Eğirdir Lake for all individuals.…”

“…In general, while the body weight of the male individuals of crayfish is greater, and their walking legs and their cheliped wider and longer, the females have a wider and longer abdomen [14]. It has been found in most of the studies done on A. leptodactylus in Turkey that due to the size of their walking legs and their weight, male individuals have a greater average length and weight compared to female individuals [14][15][16]. Similarly, the mean values that have turned out to be higher for the male population are carapace length, carapace width, abdomen length, abdomen width, cheliped length, cheliped width, total length, total weight and condition factor.…”

“…It can be concluded that the study of morphometric characters could be used to describe populations [13]. In general, while the body weight of the male individuals of crayfish is greater, and their walking legs and their cheliped wider and longer, the females have a wider and longer abdomen [14]. It has been found in most of the studies done on A. leptodactylus in Turkey that due to the size of their walking legs and their weight, male individuals have a greater average length and weight compared to female individuals [14][15][16].…”

Determination of meat productivity and biochemical composition of freshwater lobster (Astacus leptodactylus Eschscholtz, 1823) in Lake Tatlı and Lake Gici from Bafra Fish Lakes

“…In Lake Gıcı, it was determined as 3.11 in all individuals, 2.75 in females and 3.36 in males. Aydın et al [14] found the condition factor to be 2.6 in freshwater lobsters, 3.33 in male lobsters, 3.15 in females and 3.23 in all individuals. Condition factor is defined as one of the nutrition and development criteria in which the morphological structure is best controlled in lobsters by Kaya [15] .…”

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“…Deniz (Bök), Harlıoğlu, and Deval (2010) and Deniz (Bök), Aydın, and Ateş (2013) investigated morphological characteristics of A. leptodactylus. Aydin, Harlıoğlu, and Deniz (2015) investigated biological and population characteristics of A. leptodactylus. However, there is no direct study on rice.…”