The post- release survival of two skate species discarded by bottom trawl fisheries in Antalya Bay, Eastern mediterranean

Iskarta olarak tekrar denize atılan veya donanımdan kaçan balığ ın serbestlik sonrası sağ kalım oranının bilinmesi etkin bir stok değerlendirme için çok önemlidir. Bu çalışmanın amacı, Antalya Körfezi dip trol balıkçılığında en bol yakalanan iki vatoz türünün (Raja clavata ve Raja miraletus ) serbestlik sonrası sağ kalım oranlarının tahmini ve bu sağ kalımı etkileyen faktörlerin belirlenmesidir. R. clavata için, ortalama sağlık değeri, sağlık değeri 2 olanların ve sıfır zamanda ölü olanların yüzdeleri sırasıyla 2,3, %91 ve % 2 olarak hesaplandı. R. miraletus için is e bu değerler sırasıyla, 1.2, %43 ve %26.5 dır. Bu türlerin sağlık skorlarının oluşmasında, total uzunluk (P= 0.001) ve trol çekim süresi (P= 0.006) R. clavata ; çekim süresi (P= 0.046), total uzunluk (P= 0.044 idi ) ve torbadaki av miktarı (P= 0.008) ise R. miraletus için istatistiksel olarak anlamlı fa ktörler olarak belirlenmiştir. Ortalama sağ kalım süresi ve tankla ra konulduktan 48 saat sonraki ortalama sağ kalım oranı R. clavata için 41 saat ve % 81 iken, R. miraletus için bu değerler sırasıyla 15 saat ve 21% olarak hesaplandı. Tanka konan bireylerin sağlık durumu, sağ kalma oranları için çok önemli referans noktasıdır. Sağlık skorları 1 olan R. clavata ve R. miraletus bireyleri, 48 saat sonra sırasıyla % 44 ve %9 yaşam şansına sahiptirler. Diğer yandan, yaşam skorları 2 olan bireylerin sağ kalma şansı R. clavata için % 92, R. miraletus içinse % 49'a yükselmiştir.

Antalya Körfezi (Doğu Akdeniz) dip trol balıkçılığında ıskarta olarak avlanan iki vatoz türünün serbestlik sonrası sağ kalma oranı

Knowing post-release survival rates of fish escaping or being thrown back into the sea as discards is important for effective stock assessment. The aim of this study was to estimate the short-term discard survival rates of the two most abun dant by-catch skate species (thornback skate: Raja clavata and brown skate: Raja miraletus ) in the bottom trawl fisheries in Antalya Bay and to determine the factors affecting discard survival of skates. For the thornback skate the mean health score, the p ercentage with a health score 2 and percentage dead at time zero were 2.3, 91% and 2%, respectively. For brown skate, these values were 1.2, 43% and 26.5%, respectively. Considering the health score of these species, the fish length (P=0.001) and the tow duration (P=0.006) were significant parameters for the thornback skate, and the tow duration (P=0.046), the total length (P=0.044) and the catch amount (P=0.008) were found to be significant for brown skate. The mean survival time and the survival rate after 48 hours in tanks were 41 hours and 81% for thornback skate, and 15 hours and 21% for brown skate. The health condition of the individuals transferred to the tanks is an important reference point for their survival rates. Thornback and brown skates entering the tanks with a health score of 1 had a 44% and 9% chance of survival, respectively. On the other hand, skates entering the tanks with a health score of 2 or 3 had a 92% chance of survival for thornback skate and 49% for brown skate.

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