Influence of oceanic factors on Anguilla anguilla (L.) over the twentieth century in coastal habitats of the Skagerrak, southern Norway

Abstract

The European eel (Anguilla anguilla L.) is distributed all over Europe, but reproduction takes place in the Atlantic Ocean, in the Sargasso Sea. The population has been undergoing a steady decline since the 1980s. The eel is considered as critically endangered on the IUCN (International Union for the Conservation of Nature and Natural Resources) Red List of species. The objective of this study was to study the variation in eel abundance over the 20th century and determine which environmental factors are involved in the changes. This was done by analyzing data from the Skagerrak beach seine survey from Norway. This dataset constitutes the longest fishery-independent time series on eels (starting in 1904). Results showed that eel fluctuated according to changes in temperature in the Sargasso Sea and that warm temperatures had a negative effect on the number of eel larvae. The number of eels in the Skagerrak region was also dependant on current circulation in the North Sea.