Submitted to: Aquaculture Report
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/2/2019
Publication Date: 7/1/2019
Citation: Welker, T.L., Overturf, K.E., Abernathy, J.W. 2019. Effect of aeration and oxygenation on growth and survival of rainbow trout in a commercial serial-pass, flow-through raceway system. Aquaculture Report. 14:1-9. https://doi.org/10.1016/j.aqrep.2019.100194.
Interpretive Summary: Most rainbow trout produced in the United States is in flow-through raceway systems. Water in these systems is used from two to six times before exiting into a quiescent zone. Water quality is initially determined by the source water (1st use) and deteriorates as it moves through successive raceway passes. The level of dissolved oxygen (DO) is often the primary factor affecting production of rainbow trout in raceway systems. Since high DO levels promote healthy fish growth, effective DO management is essential in high-intensity production of rainbow trout. In a previous study, we observed significant negative effects on growth performance and survival with declining DO levels from upper (1st use water) to lower (5th use water) raceways. Our goal in this project was to determine if increasing the DO concentration in 5th use water to that of 3rd use water through aeration or oxygenation could improve rainbow trout growth and survival to that observed in 1st and 3rd use water. Results showed we were able to raise the average DO level in 5th use water to the level in 3rd use water by using aeration or oxygenation. Furthermore, growth performance of trout was also significantly improved in 5th use water by aeration and oxygenation. Survival was also increased for trout in 5th use water with addition of supplemental air or oxygen, but it did not reach to the survival rate of trout in 3rd use water. We concluded that decreased levels of DO was the primary factor limiting performance in lower raceways of the trout production system while the quality of other water parameters (e.g. total dissolved solids or total suspended solids) may also contribute to the reduced growth performance and survival rate.
Technical Abstract: Serial-pass raceway systems are characterized by reduced water quality as water passes from upper to lower raceways. In a previous study, we showed that rainbow trout reared in 1st use (source spring) and 3rd use (after 2 raceway passes) water exhibited significantly better growth performance and survival compared to those in 5th use water (after 4 raceway passes). The reduced performance appeared to be directly related to comparatively lower concentrations of dissolved oxygen (DO). Our objective in the present study was to determine if increasing the DO in 5th use water by aeration or oxygenation to levels in 3rd use water could improve or restore growth and physiological status of rainbow trout. We stocked rainbow trout (126±9.3 g mean weight) into tanks receiving either 1st use, 3rd use, or 5th use water with and without supplemental air or oxygen (five treatments at four tanks each). Average DO concentration was highest in 1st use (7.5 mg L-1) followed by 3rd use (6.5 mg L-1) and 5th use (5.4 mg L-1) water. In 5th use water, use of aeration (6.2 mg L-1) or oxygenation (6.7 mg L-1) raised the DO level of 3rd use water. Growth performance (% gain and FCR) and survival were significantly lower for trout in 5th use water, compared to 1st and 3rd use water. Aeration and oxygenation of 5th use water restored growth to that in 3rd use water. Compared to the control (5th use water without oxygen treatments, 35.0%), trout survival was improved significantly in 5th water use with oxygenation (74.2%) or aeration (53.1%), but these treatments could not increase survival rate to that of 3rd use water (88.8%). It was concluded that dissolved oxygen was the primary water quality parameter affecting performance in this system, while the quality of other water parameters (e.g. total dissolved solids or turbidity), which increased in 5th use water, might also contribute to the reduced performance.