Engin KOCABAŞ, ALKAN ÖZTEKİN, İSMAİL BURAK DABAN, Adnan AYAZ

Gillnet selectivity for non target fish species caught by red mullet gillnets north Aegean Sea

The aim of this study is to determine the effects of red mullet gillnets that commonly used in Turkish waters on sustainability of non target fish species. For these purpose, surveys were realized with 18 - 20 - 22 mm nominal bar length red mullet gillnets between December 2008 and May 2010 along the north Aegean Sea coasts (5-30 m). SELECT method was used with five different model (Normal location, normal scale, log-normal, gamma and bi-modal) for evaluating selectivity parameters of non target fish species. Selectivity models were determined as bi-modal for Serranus scriba and Symphodus tinca, log normal for Scorpaena porcus and Spicara maena and gamma for Pagellus acarne. Optimum catch lengths and spread values and selectivity curves were given for 5 species. Results showed that use of a larger mesh size over the 22 mm mesh is important for ensuring stock sustainability of the non target fish species.

Kuzey Ege Denizi’nde barbun uzatma ağlarında yakalanılan hedef dışı türlerin seçiciliği

Bu çalışmada yaygın olarak kullanılan barbun uzatma ağlarının hedef dışı balık türlerinin sürdürülebilirliğine olan etkisinin belirlenmesi amaçlanmıştır. Bu amaçla, kuzey Ege Denizi kıyılarında (5-30 m.) Aralık 2008 – Mayıs 2010 tarihleri arasında 18 – 20 – 22 mm göz genişliğine sahip barbun uzatma ağları ile denemeler gerçekleştirilmiştir. Hedef dışı türlerin seçicilik parametrelerinin tespitinde 5 farklı model ile (normal location, normal scale, gamma, log-normal ve bimodal) SELECT tahmin metodu kullanılmıştır. Yakalanan çizgili hani ve çırçır için bi-modal, iskorpit ve izmarit için log-normal, yabani mercan için ise gamma en uygun seçicilik modeli olarak belirlenmiştir. 5 tür için optimum yakalama boyları ve yayılım değerleri ile seçicilik eğrileri verilmiştir. Çalışma sonucunda barbun avcılığında kullanılan uzatma ağlarında ağ göz genişliğinin 22 mm’nin üzerine çıkarılmasının ilgili türlerin stok sürdürülebilirliği bakımından önemli olduğu tespit edilmiştir

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