Rearing juvenile brown Salmo trutta (L.), and rainbow trout Oncorhynchus mykiss (Walbaum), in earthen ponds with and without an induced current

ABSTRACT

Because moderate sustained exercise enhances growth in salmonids, we investigated whether paddle-wheel aerators (PWAs) used to provide juvenile brown and rainbow trout with conditions for sustained swimming can increase growth. On site a commercial farm, earthen ponds were provided with PWA and flow patterns recorded or ponds left without PWA. Growth was determined periodically and proximate body composition analyzed at 111 (rainbow trout) and 169 (brown trout) days. The PWA created circular flow patterns with a range of current speeds. First results show that brown trout reared with current had higher protein and lower fat. Rainbow trout reared with current had higher ash, lower fat, and lower energy. The current affected growth in weight of rainbow trout, while no effects on growth were observed in brown trout. PWA can also be used to create a circular flow pattern, allowing for volitional exercise at no or minor additional costs.

KEYWORDS:

• Farming technology
• growth metrics
• salmonids
• volitional exercise

Acknowledgments

The authors would like to thank the fish farmer (who wants to remain anonymous) for providing the ponds and fish for the trials of this study. The fish farmer is further thanked for his support throughout the trial as well as during sampling. A. Beiermeister is thanked for laboratory assistance. R. Yossa and four anonymous reviewers are thanked for comments on an earlier version of this manuscript. This study was supported by COST Action FA1304 “Swimming of fish and implications for migration and aquaculture (FITFISH).” The study was funded by the German Federal Ministry of Food and Agriculture (BMEL) through the Federal Office for Agriculture and Food (BLE), grant number 2813MDT902.

Disclosure statement

No potential conflict of interest was reported by the authors.

Ethical statement

All experimental procedures were conducted in accordance with national ethical guidelines as well as European Directive 2010/63/EU on the protection of animals used for scientific purposes.

Supporting information

Supporting information can be found in the online version of this article.

Supplementary material

Supplemental data for this article can be accessed on the publisher’s website

Additional information

Funding

This work was supported by the German Federal Ministry of Food and Agriculture (BMEL) through the Federal Office for Agriculture and Food (BLE) [2813MDT902].