In a standard aquaculture practice, smolts are transferred to ocean net pens without sufficient time period for osmotic adaptation, which results in significant losses to the farmer. In addition to high and unpredictable mortality rates, smolts are not able to grow optimally during their first 40-60 days in seawater. We are proposing to supplement salmon smolt feed with ARA, which may help in smoltification and alleviate the osmotic stress associated with the transfer to seawater. OBJECTIVES: The proposed project addresses one of the major constraints in achieving the full benefits of salmonid fish aquaculture, namely a consistent and cost-effective method of stress protection and fast recovery associated with the transfer of smolt to open sea cages. We are proposing to initially (Phase I) demonstrate that dietary supplementation with ARA is an efficient tool to modulate blood HSP70 induction and activity of Na+/K+-ATPase following heat shock and high salinity exposure of smolt fish. There are two main objectives for the Phase I of the project: Objective 1. Formulate ARA containing diets and test the efficacy of smolt fish to incorporate the dietary ARA in its body tissues. Objective 2. Test the stress response of ARA-fed smolt fish to high salinity and high temperature incursion. APPROACH: Smolts will be fed the 4 dietary treatments containing various levels of ARA or it precursor(3 tanks per each dietary treatment) beginning from average size of 20 g until 30 days post-transfer to full seawater. Fish weight will be recorded every 4 weeks by individually weighing all the fish in each tank. ARA effect on the fish respone to sea water exposure stress will be evaluated by the following parameters: 1) Fatty acid analysis to evaluate the efficiency of a dietary source of ARA and its incorporation into osmoregulatory tissues such as gills and kidney 2) Gill Na+/K+-ATPase analysis to evaluate the ability of ARA fed smolts to maintain homeostasis after exposure to full seawater. 3) ELISA of blood HSP70 to evaluate the potential for fast recovery of ARA fed smolts after thermal shock
