Aquacyprus-2104. 15-17 May 2014. Girne-Cyprus., Girne, Cyprus (Kktc), 15 - 17 May 2014, pp.47
Rainbow trout (
Oncorhynchus mykiss) is an important fish species for the World aquaculture industry. Due to the ion regulatory ability of rainbow trout, cage culture of this species in seawater has been in a rapid growth in recent years. Since fish farmers nowadays are challenging problems of high feed costs, it is crucial to reduce any other costs that may influence the total production profit. The loss of fish during seawater acclimatization is one of the issues reducing the capital of the production. Hence, fish transfer from fresh water hatchery to the seawater site and adaptation of fish to seawater conditions is an important matter that needs to be considered for a successful start and set out of rainbow trout culture in sea based cage aquaculture systems. In this study, the adaptation steps of rainbow trout starting from the transportation from freshwater hatchery to seawater and the acclimatization process have been observed. Two different size groups of fish (mean weights of 35g and 22 g) were transported and two different seawater acclimatization processes have been applied for each fish group, i.e., short and long term acclimatization. Transport 1 (large fish group) was carried out on 12 January 2014 while Transport 2 (small fish group) was conducted on 16 January 2014. Total of 3500 and 5500 fish were carried on the 1st and 2nd transports, respectively. In both of the transports, short term acclimatization process took 6 hours and the long term acclimatization process took 48 hours. After the transportation and seawater adaptation processes, a mortality rate of 26% was recorded for the large fish group and 43% for the small fish group in the short term acclimatization. In the long term acclimatization however, mortality rate was observed as 10% and 16% for the large size fish and small size fish groups, respectively. The objective of the present study is to evaluate seawater acclimatization of rainbow trout of different sizes with the aim of supporting trout farmers with practical information for the sustainability of marine cage aquaculture industry.