LAUSR

To contribute to improving eel stocking procedures, the survival, growth, and behaviour of farmed Japanese eels reared together with wild individuals were evaluated to learn about possible encounters of farmed-and-stocked eels with wild eels. Two experiments were conducted to evaluate (1) the effect of presence of wild eels on survival and growth of farmed eels in experimental ponds, and (2) behavioural differences between wild and farmed eels put in a small tank. In the survival and growth experiment, significantly lower survival and growth rates of farmed eels reared with wild eels were observed compared with farmed eels reared without wild eels (control). In the behavioural observations, we observed significantly higher occupation rates of a refuge and more frequent biting for wild eels, indicating a dominance of wild eels over farmed eels. Because wild and farmed eels used in the current experiments belong to the same genetic population, these differences resulted within one generation through the aquaculture rearing process. This article is protected by copyright. All rights reserved.