Marmara Denizi’nde sarıkuyruk istavrit Trachurus mediterraneus (Steindachner, 1868) uzatma ağlarının av miktarı

Abstract

Marmara Denizi’nde gırgır balıkçılığının yasak olduğu Nisan ve Haziran ayları arasında, kıyısal alanda küçük ölçekli balıkçılar uzatma ağları ile sarıkuyruk istavrit Trachurus mediterraneus (Steindachner 1868) avcılığı gerçekleştirmektedir. Bu avcılıkta hedef türün istavritin yanında, önemli miktarlarda hedefdışı türlerde avlanmaktadır. Bunun için Marmara Denizi’nde ticari bir balıkçının istavrit avcılığında kullandığı uzatma ağlarının teknik özellikleri belirlenerek, avcılık operasyonlarında yakalanan hedef ve hedefdışı türler değerlendirilmiştir. Çalışmada kullanılan multifilament uzatma ağının göz genişliği 18 mm, ip kalınlığı 210d/2, donam faktörü 0,33 ve ağın toplam uzunluğu ise yaklaşık 200 metre olarak belirlenmiştir. Ayrıca, uzatma ağlarının alt kısmına sardon ağı ilave edildiği belirlenmiştir. Avcılık operasyonlarında hedef tür istavritin yanında 29 hedef dışı türde yakalandığı tespit edilmiştir. Yakalanan hedef ve hedefdışı türlere ait toplam av miktarının 397,8 kg ve 9204 adet olduğu belirlenmiştir. Hedef tür T.mediterraneus’un ağırlık olarak toplam avın 156,5 kg’sini (%39,3) oluşturduğu belirlenmiştir. Birey sayısı olarak ise 3997 adet T.mediterraneus, toplam avın %43,4’ünü oluşturmaktadır. Birim çabaya düşen av miktarı (CPUE) T.mediterraneus için ağırlık olarak 0,026 kg/m.operasyon-1, adet olarak ise 0,7 adet/m.operasyon-1 hesaplanmıştır. Toplam avda ise ağırlık olarak 0,066 kg/m.operasyon-1, birey sayısı olarak 1,5 adet/m.operasyon-1 hesaplanmıştır. Uzatma ağları ile T. mediterraneus hedeflenen bu avcılıkta hedef türden 9390 TL (%59,4), hedefdışı ticari olarak değerlendirilebilen türlerden ise 6424,4 TL (%40,6) olmak üzere toplam 15814,4 TL kazanç sağlanabileceği hesaplanmıştır. Bu çalışma önemli bir balıkçılık alanı olan Marmara Denizi’nin kıyısal alanında ticari balıkçıların T. mediterraneus türünü avlamak için kullandıkları uzatma ağlarının av veriminin ilk kez ortaya konması bakımından önem taşımaktadır. Bu sonuçların türe özgü kullanılan av araçlarının yönetim planlarının oluşturmasına ve balıkçılık yönetimine katkı sağlayacağı düşünülmektedir.

Keywords

• Kıyısal alan
• hedef tür
• hedefdışı tür
• balıkçılık yöntemi
• ekenomik değer

Project Number

This study was supported by TUBITAK 2209-A University Students Research Projects with application number 1919B012300624.

Ethical Statement

Yukarıda bilgileri yer almakta olan çalışmamın/çalışmamızın Orman ve Su İşleri Bakanlığı’nın 2014 yılındaki HAYVAN DENEYLERİ ETİK KURULLARININ ÇALIŞMA USUL VE ESASLARINA DAİR YÖNETMELİ’ğinin (Sayı:28914) 8. Maddesine ölü balıklarda sadece toplam ağırlık ölçümü yapılması, Madde 10’a göre herhangi bir canlı hayvan ile çalışılmaması, Madde 11.’e göre bir deney hayvanı olmaması ve ölü balıklara herhangi bir kimyasal işlem uygulanmamasısebepleriyle etik kurul izni gerektirmeyen çalışmalar arasında yer aldığını beyan ederim/ederiz.

The catch amount of Mediterranean horse mackerel Trachurus mediterraneus (Steindachner, 1868) gillnets in the Sea of Marmara

Abstract

The small-scale fishermen in the coastal area of the Marmara Sea between April and June caught the Mediterranean horse mackerel Trachurus mediterraneus (Steindachner, 1868) with gillnets. This target species, T.mediterraneus and significant amounts of non-target species are caught in these nets. So, the technical and structural characteristics of the gillnets for a commercial fishermen were determined and the target and non-target species were evaluated in catching operations. The multifilament gillnet mesh size of 18 milimeters polyamid, twine thickness of 210d/2, hanging ratio of 0.33 and the total length of approximately 200 meters. Also, guarding nets were added to gillnets. The total amount was determined as 397.8 kilograms (kg) and 9204 individuals (ind). The weight of T.mediterraneus was constituted 39.3% of the total weight. The in of T.mediterraneus was constituted 43.4% of the total ind. While the catch per unit effort (CPUE) for T.mediterraneus was calculated at 0.026 kg/m.operation-1 and 0.7 ind/m.operation-1, the CPUE for the total amount was calculated at 0.066 kg/m.operation-1 and 1.5 ind/m.operation-1. The total economic value was calculated at 15814.4 Turkish Liras (TL), which 9390 TL from T.mediterraneus and 6424.4 TL from non-target species. This study is important in terms of revealing for the first time the catch efficiency of gillnets used by commercial fishermen to catch T.mediterraneus in the coastal area of the Marmara Sea, which is an important fishing area. These results will contribute to the creation of management plans and fisheries management for species-specific fishing gear used in a region.

Keywords

• Coastal area
• target species
• non-targeting species
• fisheries management
• economic value

Supporting Institution

This study was supported by TUBITAK 2209-A University Students Research Projects with application number 1919B012300624.

Project Number

This study was supported by TUBITAK 2209-A University Students Research Projects with application number 1919B012300624.

Thanks

This study was supported by TUBITAK 2209-A University Students Research Projects with application number 1919B012300624. The authors grateful to captain Ahmet ŞEN of Yusuf Kaptan 17 fishing boat for providing the fishing operations. The study was presented as oral presentation at “The 2nd International Conference and the 4th National Conference on Marine Sustainable Development” in Iranian.

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