Özgür Emiroğlu

Alien fish species in upper Sakarya River and their distribution.

Sakarya River is one of the most important fishing areas in Turkey. The river provides reproduction and survival areas which are suitable for many fish species by means of both the warm water sources and the wide flood plains. However, the fact that the flood plains have been reclaimed, excessive hunting, destruction of the ecologic balance and invasion of the area by the alien fish species threatens the fish stocks in Sakarya River. In this study, we aimed to determine the dispersion area of Carassius gibelio (Bloch, 1782), Oreochromis niloticus (Linnaeus, 1758) and Clarias gariepinus (Burchell, 1822) as the alien fish species. Between years 2005 and 2010, the dispersion areas of these three species in Sakarya River have been determined by means of catching in irregular time periods in the entire Sakarya River. The dispersion details of every of the three species has been yielded with this study for the first time and the natural populations created by O. niloticus in Sakarya River was determined for the first time in this study. Key words: Carassius gibelio, Oreochromis niloticus, Clarias gariepinus, Sakarya River.

The life-history traits of widespread freshwater fish species: the case of Roach Rutilus rutilus (Linnaeus, 1758) (Pisces: Teleostei) in water bodies at the southern limits of distribution

The Roach Rutilus rutilus (Linnaeus, 1758) (Pisces: Teleostei) is a widespread Eurasian cyprinid freshwater fish. Although numerous studies have investigated the species’ life history traits across its main native range of distribution, little is known from water bodies located beyond the southern limits of the latter, especially where the species has been introduced. Between July 2010 and April 2011, a total of 949 R. rutilus specimens was collected from Porsuk Reservoir (NW Turkey), and life-history traits of age, growth, fecundity and egg size were studied and compared to six other R. rutilus populations (including Caspian Roach R. r. caspicus) from the southern limits of distribution. The Porsuk population was characterised by relatively shorter lifespan, slower growth and lower fecundity. These findings support previous studies emphasising the importance of local environmental factors in shaping the life-history traits of widespread fish species. These must be taken into consideration especially in view of the potential value of R. rutilus as an economic resource for in-land fisheries.

Maden Havzası Balıklarında Vücut Ağırlığı ile Ağır Metal Biyoakümülasyon İlişkileri: Emet Çayı Havzası

Bildirildigi gibi, farkli fizyolojik yapilara sahip degisik balik turleri, agir metallere maruz kalma surelerine ve maruz kalinan metalin cesidine gore, agir metalleri farkli dokularda farkli miktarlarda biriktirmektedirler. Baliklarin yasi, dolayisiyla yasa paralel artis gosteren agirliklari, dokulardaki toksik element biyoakumulasyonlarinda onemli bir faktordur. Bu calismada, ulkemizin en onemli maden yataklarinin yer aldigi Emet Cayi uzerinde tespit edilen uc ve yine Emet Cayi Havzasi’nda yer alan Dursunbey Cayi uzerinde tespit edilen bir istasyondan mevsimsel olarak, havza icin en buyuk onem arz eden Squalius cii , Capoeta tinca ve Barbus oligolepis turleri, gerekli miktarlarda toplanmistir. Yakalanan baliklarin kas, solungac, karaciger ve bobrek dokularinda tespit edilen nikel, cinko, arsenik, bor, kadmiyum, bakir, mangan, kursun, gumus ve krom biyoakumulasyon seviyelerinin balik agirliklari ile iliskileri arastirilmistir. Elde edilen verilere, SPSS 17 istatistik programi kullanilarak Pearson Korelasyon Analizi uygulanmis, yuksek korelasyon gosteren degiskenlerin uc boyutlu regresyon grafikleri cizilmis ve regresyon katsayilari hesaplanmistir. Calismamiz sonucunda, balik dokularinda tespit edilen toksik element biyoakumulasyonlari ile baliklarin total agirlik verileri arasinda anlamli iliskiler kaydedilmistir.