Several pump systems are currently in use during management operations at aquaculture facilities. A new pump system; The new (MMC) RID pump system was compared to traditional pump systems to assess whether the RID system produced lower stress responses in Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss).
The stress response of fish was measured by analyzing circulating cortisol levels in blood plasma at different stages during the pumping process. The following samples were taken:
1. Before the fish enters the pump system
2. Fish arriving in the first tank
3. Fish arriving at the next tank after pumping for 1 hour
4. The fish arriving in the last tank.
Cortisol levels were generally higher in salmon than in rainbow trout. The analyzes showed a lower concentration of the stress hormone cortisol in both salmon and rainbow trout after pumping with the RID pump compared to vacuum pump and centrifugal pump. The RID pump contributed to a lower cortisol level throughout the pumping process, especially in Atlantic salmon, where a significant ly lower cortisol concentration was observed in the last part of the process.
This study is part of our effort to develop user-friendly tools for identifying the fish’s stress response to their surroundings and to various farm operations . These methods makes it possible for farmers, authorities and technology suppliers to test various events in fish farming , without the fish being killed. This opens new possibilities of identifying fish stressors and the extent of stress the event or environmental conditions is causing. This also opens the possibility of developing and identifying operating and technology systems that contribute to improving welfare of farmed fish.