Evaluation of rainbow trout (Oncorhynchus mykiss) mariculture on the Turkish Black Sea coast

Rainbow trout (Oncorhynchus mykiss) of nine months (trial I) and 1.5 years (trial II) were reared in cages in the southern Black Sea to assess growth performance. The effects of stocking density and size of fish at transfer t o sea water on growth were also examined. Initial mean weights were around 30 and 200 g and stocking densities were 660, 990, 1320 and 800, 1000, 1500 and 2000 fish per cages of 56 m(3) in trials I and II, respectively. Final mean weights at the end of 180 days were 589.4 (+/-15.2) - 633.9 (+/- 10.4) g in trial I and 1038.3 (+/-22.5) - 1227.5 (+/-28.1) g in trial II at water temperatures ranging 6.7-17.5 degrees C. Biomass at harvest ranged f rom 7.4 to 40.2 kg per m(3) depending on the initial stocking density. Grow th was affected when density reached over 25 kg m(3) and, according to grow th rates, the optimum stocking density at harvest was estimated as 20-25 kg m(3). Specific growth rates and food conversion ratios varied 0.46-3.26% a nd 1.54-2.13, respectively. Mortality ranged from 3.1% to 4.6%. it has been concluded that mariculture of rainbow trout on the southern coast of the B lack Sea can be carried out approximately eight months of the year. It is possible to produce portion size fish (200-250 g) by stocking small f ish of around 15-30 g and conducting multiple harvests in one culture seaso n. However, production of large or salmon trout (2-3 kg) needs development of more suitable technology and culture strategies.