| Abstract |
The critical status of the catadromous European eel is addressed with European wide conservation efforts. One option is conservation-oriented restocking where juvenile glass eels are caught upon their arrival at the European continent and transferred to waters with no or limited natural recruitment caused in part by fragmented migration routes. In light of the critical stock status, conservation oriented restocking activities needs to be conducted in a careful and informed manner. Due to warmer winters and better glass eel availability, glass eels have increasingly been restocked in Germany during winter in recent years, and not as usual in spring. However, it is not known if restocking in winter reduces glass eel survival due to colder temperatures and limited food availability compared to the traditional restocking approach. In this study, growth and survival rates for glass eels restocked in winter were estimated in five isolated lakes. The generated data were compared to values of a previous study where glass eels were restocked in the same lakes during spring. This comparison indicates that glass eels restocked in winter had similar survival rates (19–45%) and growth performance to those released in spring. Accordingly, restocking glass eels in the winter is a suitable alternative compared to traditional release in spring. |