Süleyman ÖZDEMİR, Yakup ERDEM, Ercan ERDEM

The Determination of Size Selection of Whiting (Merlangius merlangus euxinus) by Square Mesh Panel and Diamond Mesh Codends of Demersal Trawl in the Southern Part of Black Sea

Ergin olmayan küçük balıkların yakalanmasını azaltmak için trol torbalarında bazı değişikliklerin yapılması sürdürülebilir balıkçılık için kullanılan yönetim araçlarından biridir. Bu araştırmada mezgit (Merlangius merlangus euxinus) balığı için demersal trol torba seçiciliğinde kare gözlü kaçış panelinin etkileri incelenmiştir. Seçicilik denemelerinde trol torbasının üst kısmının ön bölümüne 36 mm ve 40 mm kare gözlü kaçış panelleri yerleştirilmiş ve 40 mm baklava gözlü polietilen torba kullanılmıştır. Araştırma Karadeniz'in güney kıyılarında 2006 yılı Şubat ve Mart ayları arasında ticari balıkçı gemisinde yürütülmüştür. Torba üzerinde çemberli örtü torba yöntemi kullanılarak toplam 6 geçerli ağ çekimi yapılmıştır. Seçicilik parametreleri maksimum benzerlik yöntemi ve lojistik denklem kullanılarak hesaplanmıştır. Mezgit balığının ortalama L50 ve seçicilik aralıkları sırasıyla 40 mm baklava gözlü ağ için 12,57 (se. 0,41) cm ve 3,45 (se. 0,03) cm, 36 mm kare gözlü panel için 12,71 (se. 0,45) cm ve 3,12 (se. 0.03) cm, 40 mm kare gözlü panel için 13,55 (se. 0,32) cm and 3,70 (se.0,02) cm olarak belirlenmiştir. Araştırma sonuçları, trol torbasının üst bölümünün ön kısmında kare gözlü panel (40 mm) kullanımının demersal trol torbasının seçiciliğini artırdığını ve yavru mezgit balıklarının yakalanmasının azaldığını göstermektedir.

Karadeniz'in Güneyinde Kare Gözlü Panel ve Baklava Gözlü Torbaya Sahip Demersal Trol ile Mezgit (Merlangius merlangus euxinus) Balığının Boy Seçiciliğinin Belirlenmesi

The modification of the trawl codends to reduce the capture of juvenile fish increasing of fishing gear selectivity has been one of the management tools for sustainable fisheries. This study were examined the effect of square mesh escape panel installation on selectivity of demersal trawl codends for whiting (Merlangius merlangus euxinus, N.) in the Black Sea. Codend mesh selectivity experiments were carried out using 40 mm nominal diamond mesh PE codend with 36 mm and 40 mm mesh size square mesh escape window inserted in the forward part of the top panel. The experiments were carried out in the southern Black Sea between February and March 2006 on a traditional fishing boat. A total of 6 valid hauls were made by using the hooped covered codend method. Selectivity parameters were calculated by using a logistic equation with the maximum likelihood method. Mean L50s and selection ranges of whiting were determined as 12.57 (se. 0.41) cm and 3.45 (se. 0.03) cm for 40 mm nominal diamond mesh, 12.71 (se. 0.45) cm and 3.12 (se. 0.03) cm for 36 mm square mesh panel and 13.55 (se. 0.32) cm and 3.70 (se. 0.02) cm for 40 mm square mesh panel, respectively. The results shows that the use of square mesh panel (40 mm) in the forward part of the top panel reduce the capture of juvenile fish and increases the demersal trawl codend selectivity.

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