The estimation of stocked and natural European eel (Anguilla anguilla) populations in Estonian waters

• Main Author: Bernotas, Priit
• Other Authors: Vetemaa, Markus (advisor), Nõges, Peeter (advisor), Ložys, Linas (opponent), Institute of Agricultural and Environmental Sciences
• Format: Doctoral or Postdoctoral Thesis
• Language: unknown
• Published: Estonian University of Life Sciences 2024
• Subjects: dissertations; Green University (thesis is related to EMÜ Green University iniciative’s aims); eel; populations (biology); population parameters; Estonia; Anguilla anguilla
• Online Access: http://hdl.handle.net/10492/9088; https://doi.org/10.15159/emu.137

A Thesis for applying for the degree of Doctor of Philosophy in Applied Biology. Väitekiri filosoofiadoktori kraadi taotlemiseks rakendusbioloogia erialal. Eels, due to their mysterious life cycle and appearance have long fascinated scientists and fishers alike. In Estonia, similarly to the rest of Europe, eel populations have faced dramatic changes over the last decades, giving researchers a tough task to find out the factors behind these changes. My thesis focused on different aspects regarding the fisheries and welfare of eel in Estonian coastal and freshwater habitats. We studied a long-time series of commercial landings, scientific surveys, restocking efforts, and environmental variables, to shed light on the dynamics of these mysterious creatures. One observation from our investigation is the decline in both commercial and recreational landings of eels along the Estonian coast since the 1970s where data was available. This trend is consistent with a broader pattern seen all across Europe. However, with the fall of the Soviet Union at the beginning of the 1990s there was a sudden growth in eel landings on the Estonian coast. This was most probably due to changes in fishing practices, improvement in registering the catches, and growth in fishing effort rather than the recovery of local eel stocks. Since 2008 the landings of small fyke nets in particular dropped sharply with the main reason aside from the declining eel population being reduced effort as well as the diminishing profitability of using such gear. As opposed to small fyke nets, the number of large fyke net licenses remained unchanged. As eels are not specially targeted by large fykes the changes in the eel landings also reflect the decline of eel biomass in the coastal areas. Restocking is a part of eel management strategies in many European countries, including Estonia. Initially aimed at preserving traditional eel fisheries, most notably in Lake Võrtsjärv, restocking programs have evolved in response to declining stocks and regulatory ...