Yolk sac consumption and growth rates of Black Sea trout alevins (Salmo trutta labrax Pallas, 1811) at three different water temperature regimes

In this study, yolk sac consumption and growth rates of Black Sea trout, Salmo trutta labrax (Pallas, 1811), alevins from hatch to swim-up stage were determined, and relationships between degree-days and alevins length, total wet, dry yolk, dry body weights, and dry matter rate were calculated. The eggs were hatched at 9.0± 0.54°C water temperature, and hatched alevins were divided randomly three groups about 1700 individual. The first group was hatching water temperature, second group was 16°C, heated by thermostatic heaters, and the last group was 5°C, temperature changed naturally. While at hatching, mean alevins length and total dry weight values 11.65±0.47 mm and 26.87±1.47 mg, at swim-up stage these values were measured as 23.00±0.58 mm and 20.98±1.69 mg at 5°C group, 21.80±0.67 mm and 19.27±1.74 mg at 9°C group, and 21.35±0.67 mm and 17.74±2.45 mg at 16°C group, respectively. The length and total dry weight values showed significant (P<0.001) among the groups at swim-up stage. While length and weight increased rates, length and weight specific growth rates, and yolk sac conversion efficiency values of 5°C group were higher significantly (respectively, P<0.05, P<0.05, P<0.01, P<0.01, P<0.01) than the others, 9°C and 16°C groups were similar. Significantly relationships were determined between degree-days and alevins length, total wet, total dry, dry yolk sac, and dry body weights. The time to reached first swim-up stage was shorter at 16°C group, but alevins weight values were lower (P<0.001) than the others. Maximum benefit from yolk sac was determined at 5°C group. The degree-days values showed difference from hatch to swim-up stage.  

Çalışmada, Karadeniz alabalığı (Salmo trutta labrax Pallas, 1811) larvalarının, serbest yüzme anına kadar olan besin kesesi tüketimleri ve büyüme oranları belirlenmesi, gün-derece ile larva boyu, toplam yaş ağırlık, kuru kese ağırlığı, kuru vücut ağırlığı ve toplam kuru madde oranı arasındaki ilişkiler ortaya konması amaçlanmıştır. Yumurtaları çıkışa kadar su sıcaklığı 9.0± 0.54°C olan kaynak suyunda kuluçkalanmış ve çıkışı takiben larvalar her grupta yaklaşık 1700 adet olacak şekilde rasgele olarak üç gruba ayrılmıştır. İlk grup (9°C), kuluçkalamanın gerçekleştiği, ikinci grup (16°C) ve son grup (5°C) ise su sıcaklığının tamamen doğal olarak değişen dere suyunda kuluçka edilmiştir. Yumurtada çıkış anında ortalama larva boyu 11.65±0.47 mm ve toplam kuru ağırlık 26.87±1.47 mg iken, serbest yüzmede bu değerler sırasıyla 5°C grubunda 23.00±0.58 mm ve 20.98±1.69 mg; 9°C grubunda 21.80±0.67 mm ve 19.27±1.74 mg ve 16°C grubunda ise 21.35±0.67 mm ve 17.74±2.45 mg olarak ölçülmüştür. Serbest yüzmede boy ve toplam kuru ağırlık değerleri, gruplar arasında önemli farklılıklar (P