The European catfish, Silurus glanis, is native to eastern Europe and western Asia and is among the largest freshwater fish in the world. Despite its increasing economic importance and its frequent introductions, the ecology and life-history of this species is poorly known due to the difficulty of sampling such a large species in large rivers and standing waters. Our study provides the first data on age and growth of this species in Turkish waters, where it is native. We report the length-weight relationships and age and size structure of this population, which were significantly different between females and males. A marginal increment analysis indicated that annulus formation occurred between May and June. The estimates of three growth functions (von Bertalanffy, logistic and Gompertz) are reported, with the von Bertalanffy growth providing a better fit and more realistic parameter estimates. Growth rates were significantly higher in males than in females and were overall higher compared to other native populations but similar to introduced populations of similar latitudeEGB was supported by the Spanish Ministry of Science (projects CGL2009-12877-C02-01 and Consolider-Ingenio 2010 CSD2009-00065)

The study describes some key elements of the reproductive biology, including spawning season, age at sexual maturity, fecundity and egg diameter of the native brown trout, Salmo trutta macrostigma, in a tributary of the Ceyhan River. A total of 197 brown trout (118 females and 79 males) were captured in 2000-2001 by electric fishing. In observations on monthly changes, the gonadosomatic index (GSI) and the monthly frequency distribution of egg diameter confirmed that spawning lasted from November to January. Some 27.7% of the females and 62.5% of the males attained sexual maturity in their second year. The smallest fork length (FL) of brown trout attaining sexual maturity was 17.4 cm for males and 17.8 cm for females. Mean fecundity in age groups II, III, IV and V were 360, 452, 693 and 1283 eggs per female, respectively. One 9-year-old female had a unique 3232 egg count. The mean fecundity of the sampled population was 554 eggs per fish, positively correlated with the FL (mm) (R ¼ 0.8227 ) and body weight (R ¼ 0.8130). The diameter of mature eggs in the spawning season ranged from 3.250 to 5.930 mm, with a 4.146 mm average. Mean egg diameter in age groups II, III, IV and V in the spawning season were 0.813, 3.799, 4.663 and 5.243 mm, respectively. Fecundity, egg weight and diameter were statistically different in all age groups.

Fish fauna in the upper and middle Ceyhan River basin were investigated with the distribution and systematical determination from May 2001 to April 2004. The fish specimens were obtained by electro fishing and gill nets from two lakes, two reservoirs and 18 streams. A total of 2,414 specimens were collected and 1,156 of these were investigated diagnostic characteristics. Twenty species belong to 10 families were determined. Salaria fluviatilis present stations which under 750 m altitudes while Anguilla anguilla was not present in the upper Ceyhan River basin. S. t. macrostigma was also determined in the streams and river located between 720-1,474 m altitudes. Capoeta angorae, Garra rufa and Alburnus orontis were showed a large distribution in the Ceyhan River system. Gambusia affinis and Clarias gariepinus were determined only in Gavur Lake canals and Kumaşır Lake. Acanthobrama sp. only presented in Sır Reservoir, Silurus glanis and Squalius kottelati presented in Sır lake canals and Menzelet lake reservoir, Cobitis evreni and Aphanius mento were determined in the vegetative areas. Anguilla anguilla bireyleri yukarı Ceyhan havzasında bulunmaz iken Salaria fluviatilis bireyleri 750 m rakımı altındaki istasyonlarda mevcuttur. S. t. macrostigma bireyleri ise 720 ile 1.474 m rakımdaki akarsu ve çaylarda bulunmaktadır. Capoeta angorae, Garra rufa ve Alburnus orontis Ceyhan nehir sisteminde çok geniş bir dağılım göstermiştir. Gambusia affinis ve Clarias gariepinus sadece Gavur Gölü kanalları ve Kumaşır Gölü'nde belirlenmiştir. Acanthobrama sp. sadece Sır Baraj Gölü'nde; Silurus glanis ve Squalius kottelati Sır Baraj gölü kanallarında ve Menzelet Baraj gölünde, Cobitis evreni ve Aphanius mento ise bitikisel floranın olduğu lokalitelerde belirlenmiştir.Anahtar Kelimeler: Ceyhan Nehir havzası, balık faunası, dağılım.

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