Tools and triggers for eel reproduction

Abstract

Freshwater eels (Anguilla spp.) intrigued scientists for centuries. Their life cycle involves for example two distinct larval stages and a long distance migration, which may cover thousands of kilometers. The farming of eels is still dependent on the influx of wild glass eels, because eels do not mature naturally in captivity due to strong neural inhibition. Since the 1980s, the glass eel influx of several eel species drastically declined. The European eel (A. anguilla) was recently enlisted by the IUCN as a critically endangered species; therefore there is an urgent call for eel management and artificial reproduction. Artificial reproduction may contribute to restoration of the eel population by releasing the current fishing pressures on the wild stocks, and allowing a sustainable eel aquaculture in the future. Although, artificial reproduction by applying hormone treatments is possible to some extent, success ra tes are still far from creating a sustainable aquaculture. This thesis focuses on the spawning migration, maturation and reproduction of eels. New tools are developed that may improve current artificial maturation and reproduction protocols for eel aquaculture.