The effects of a commercial trout feed (45% crude protein, 12% crude fat) and a carp diet (35% crude protein, 10% crude fat) on growth performance of Russian sturgeon (Acipenser gueldenstaedtii) was studied and expressed as weight gain (WG), specific growth rate (SGR), feed conversion ratio (FCR) and body composition (protein, lipid and dry matter).). 23-months old sturgeons were hand-fed (pelleted diets) twice daily throughout the 330-day experimental period. Fish were grown at ambient temperatures (seasonal range: 6.2-26.3 ºC). Initial mean weight in the two groups was 399 ± 12 g and 404 ± 13.1 g, respectively. Mean weight gain in the two groups was calculated to be 95.3% in fish fed the trout pellets (Group 1) and 77.3% in fish fed the carp pellets (Group 2). Mean specific growth rate (SGR) in sturgeons fed the trout and carp diets was found to be 0.19 and 0.16, respectively. Mean feed conversion ratio (FCR) for both test groups was 4.9 and 5.2, respectively. Corresponding crude protein values, were 19.04% and 18.21% in muscle tissue, respectively. The results indicated that growth performance of Russian sturgeons using trout diets seem to be somewhat better than that of the fish fed the carp feed. However, growth performance (WG, SGR and FCR) and body composition were not statistically different in two groups.

The growth performance of juvenile sturgeon (Acipenser gueldenstaedtii Brandt & Ratzenburg, 1833) was studied in experimental net cages (2 m · 2 m · 2 m) in freshwater Sapanca Lake. Fertilized eggs were imported from Krasnodar, Russia in January 2001. Two experimental stocking densities were employed (12 and 8 ind. m )3 ). Sturgeon were hand-fed a pelleted commercial trout feed twice daily throughout the 203-day experiment period. Fish were grown at ambient temperature (12.7-28.5°C) and natural photoperiod. Initial and final mean body weights were 279.5 g (±31.27) and 1112.8 g (±234.77) in the first group, and 271.1 g (±28.21) and 1140.5 g (±213.31) in the second group, respectively. Results were a fourfold biomass density increase in both trials from an initial 3.48 to 12.4 kg m )3 (high density) and 2.2 to 8.8 kg m )3 (low density). Mean specific growth rate (SGR) was determined as 2.69% day )1 in both groups. Mean condition factor (CF) at the end of the experiment was 0.36 ± 0.05 in the high-density group and 0.41 ± 0.05 in the low-density group. Mean feed conversion ratio (FCR) was calculated to be 5.7 and 5.8, respectively. Survival was 92.7% in the first group (high density) and 96.1% in the second group (low density). The results demonstrated that sturgeon juveniles can be raised in cages and that growth performance (CF, SGR and FCR) and mortality of sturgeon were not significantly different at the two stocking densities (P > 0.05) tested.

This paper presents data on the concentrations of 5 metals, copper (Cu), cadmium (Cd), iron (Fe), zinc (Zn) and lead (Pb) in Blue Whiting sampled from the Eastern Black Sea coast of Turkey. The highest metal concentrations of Cu, Cd, Fe, Zn and Pb were recorded in Blue Whiting with the values of 2.71, 0.601, 14.137, 15.322 and 1.078 µg g -1 dry weight, respectively. On average the metal concentrations in Blue Whiting followed the order of Zn > Fe > Cu > Pb > Cd. Temporal differences of concentrations of these metals were significant (p < 0.05).

Çalışmada, Karadeniz alabalıklarının deniz suyu adaptasyonunda fizyolojik tepkilerinin ortaya konulması amaçlanmıştır. Kasım ayında 11 aylık yaşta balıkların iki benzer grupta deniz suyuna muamelesinden sonra, balıkların bireysel adaptasyon başarısı morfometrik olarak incelenmiştir. Smoltifikasyon başarısının belirlenmesi için, balıklar parr markalarının durumuna göre sınıflandırılmıştır. Yapılan analiz sonucunda, Karadeniz alabalıkların 11,5 cm boydan itibaren smoltifikasyon başarısı gösterdikleri tespit edilmiştir. Deneme grubu balıklar ortalama 11 cm boy ve 11,6 g olacak şekilde, rastgele iki eşit gruba ayrılmışlardır. Her iki grup Kasım-Nisan Karadeniz tuzluluğunda ve tatlı suda beslenmişlerdir. 5 ay süre ile izlenen balıklarda deniz suyu grubunda 15,8±2,79 cm, tatlı su grubunda 16,1±2,05 cm boy ortalamasına ulaşılmıştır. ‰18 tuzluluğa maruz bırakılan gerekli boyun üzerindeki balıkların kan plazma sodyum ve klor iyonları seviyesi ilk 3 günde ani bir artış gözlenirken, 7. günden itibaren durağanlık kazanmıştır. Potasyum iyonu seviyesi 17. güne kadar azalmış, bu günden sonra sabitlenmiştir. Balıklar okyanus tuzluluğuna (‰30) maruz bırakıldıklarında, kan plazması iyon seviyelerinin 14. günden itibaren sabit düzeye ulaştığı tespit edilmiştir. Deniz suyuna adaptasyon sürecinde, ‰18 tuzlulukta herhangi bir ölüm gözlenmezken, ‰30 tuzlulukta toplamda %10 ölüm oranı gözlenmiştir. Sonuç olarak, 11,5 cm boy grubunun üzerinde Karadeniz alabalığının ‰18 tuzluluğa adaptasyonunun başarılı olabileceği, fizyolojik adaptasyon süresinin 17 gün sürdüğü belirlenmiştir. Karadeniz alabalığının deniz suyuna salıverilmesi uygulamalarında, belirlenen bu boy grubunun üzerindeki balıkların 17 günden daha fazla adaptasyon süresi tercih edilirse, salıverilen balıkların rekabet gücü ve yaşama oranı artacaktır.