Determination of the Effect of Salinity and Temperature on the yolk sac consumption of Abant trout (Salmo abanticus Tortonese, 1954) Alevins

In this study, the effects of salinity and daily temperature fluctuations on the yolk sac consumption of Abant trout (Salmo abanticus Tortonese, 1954) alevins were evaluated. To determine the effects of temperature fluctuations, two different water sources; surface water (S-dere) and spring water (S-kynk), to determine the effects of salinity three different concentrations; ‰4 (Tuz-4), ‰6 (Tuz-6), ‰8 (Tuz-8) were used. The average water temperature of the groups was set to be similar. After 95% of the eggs hatched the alevins were transferred to experiment tanks. The first day the alevins transferred to experiment tanks was counted as the 1. sampling and samples were taken every five days. The highest average length and length growth rate had measured in S-dere group (23.80 ± 0.72 mm and 0.26 ± 0.01 mm/day) respectively and there are statistically significant differences between all groups (ANOVA, P<0,001). S-dere group consumed their yolk sac earliest than other groups. Daily dry yolk sac absorption was measured in S-dere group (0.75 ± 0.02 mg/day) and there are significant statistically differences in all groups. The highest average wet weight of alevins was measured in S-dere group (91.30 ± 6.21 mg) and the lowest one was also measured in Tuz-4 group (66.73 ± 4,18 mg). Throughout this study, the highest weight growth rate was calculated in S-dere group as 1,90 ± 0,03 mg/day, the lowest one was Tuz-4 as 1,12 ± 0,05 mg/day. Yolk sac conversion efficiency was determined as the highest in S-kynk group (0.61 ± 0,03 mg/mg) and as the lowest in Tuz-4 group (0.35 ± 0.03 mg/mg) As a result, the best growth performance and growth efficiency on Abant trout alevins yolk sac consuming stage was determined in freshwater with daily fluctuating temperature conditions. On the other hand, the lowest larval growth was observed under ‰4 salinity condition.