Yüksel, Fahrettin; Demirol, Ferhat; Gunduz, Fatih; Coban, Mehmet Zulfu

In this study, it was aimed to determine the selectivity properties of the gillnets used for Shabbout (Arabibarbus grypus Heckel, 1843) in Keban Dam Lake, Turkey. Experiments were carried out at 3 different stations of the dam lake using 5 monofilament gillnets with 40, 50, 60, 70, 80 mm nominal mesh size (bar length). A total of 510 target species between 38 and 79.2 cm in total length were caught in 47 catching trials. The select method was used to estimate the selectivity parameters. When the model deviations were compared, the lowest deviation (183.6104) was observed to be given by the lognor-mal model. According to this model, optimum catch lengths of nets which have 40, 50, 60, 70, 80 mm mesh size determined as 40.12, 50.15, 60.18, 70.21, 80.24 cm and their spread values 3.03, 3.79, 4.55, 5.30, 6.06 cm, respectively. The differences between the length frequencies of the fish caught by all nets were found to be significant according to the Kolmo-gorav-Smirnov test. Minimum catch size of Shabbout is notified as 45 cm in Turkey. According to results of this study, gillnets with 50 mm and above mesh size do not cause an overfishing on Shabbout stocks.

AtıfScopus3

İncele

Yuksel, Fahrettin; Cilbiz, Mehmet; Demirol, Ferhat; Capkin, Kadir; Bektas, Zubeyde Hanoi; Gunduz, Fatih

Narrow-clawed crayfish (Astacus leptodactylus Eschscholtz, 1823) is native species to Turkey and the most important shellfish because of its commercial value and ecological role in ecosystem. The knowledge on bio-ecological features of narrow-clawed crayfish is limited. In this study, total length (TL), carapace length (CL), carapace width (CW), abdomen length (AL), abdomen width (AW), chela length (ChL) and chela width (ChW) of narrow-clawed crayfish were compared in two different habitats (Egirdir Lake and Keban Dam Lake). According to linear regression analysis, the highest relation was between TL and AL (R2=0.987) of the female in Egirdir Lake and the weakest relationship was between AW and ChL (R2=0.084) in Keban Dam Lake. Overall, the biometric features of A. leptodactylus populations in Egirdir Lake and Keban Dam Lake were different and these differences were significant in mid-length groups. These findings clearly demonstrated the impact of commercial catching on the length distribution of the crayfish stocks.

AtıfScopus5

İncele

Yuksel, Fahrettin; Gunduz, Fatih; Demirol, Ferhat

A study was conducted to determine the selectivity of monofilament gillnets with mesh sizes of 50, 60, and 70 mm that are used in Keban Dam Lake for fishing Luciobarbus esocinus (Heckel, 1843). During the study, a total of 394 L. esocinus were caught. Selectivity parameters were estimated using the indirect estimation method developed by Holt (1963). Optimum selection lengths for L. esocinus were calculated to be 36.61, 43.94 and 51.26 cm for gillnets with mesh sizes of 50, 60, and 70 mm, respectively. Common selectivity factor was estimated to be 7.32, with standard deviation 4.58. Length at first maturity of female L. esocinus (50 cm) was compared to the optimum selection lengths of gillnets with mesh sizes of 50, 60, and 70 mm. Results indicate that gillnets with mesh size of 70 mm would be appropriate for harvesting L. esocinus in the Keban Dam Lake, as the optimum selection length (51.26 cm) is greater than length at first maturity.

AtıfWoS4

İncele