Age of European silver eels during a period of declining abundance in Norway ...

• Main Authors: Durif, Caroline, Diserud, Ola, Vøllestad, Leif Asbjørn, Sandlund, Odd Terje, Thorstad, Eva, Bergesen, Knut, Poole, Russell, Shema, Steven, Escobar-Lux, Rosa
• Format: Dataset
• Language: English
• Published: Dryad 2020
• Subjects: silver eel; Anguilla anguilla; critically endangered; species recovery; Norway; European eel
• Online Access: https://dx.doi.org/10.5061/dryad.2jm63xskk; https://datadryad.org/stash/dataset/doi:10.5061/dryad.2jm63xskk

The European eel (Anguilla anguilla) is critically endangered throughout its range. Knowledge about age distribution of future spawners (silver eels) is essential to monitor the status and contribute to the recovery of this species. Determination of age in anguillid eels is challenging, especially in eels from the northern part of the distribution area where growth is slow and age at maturation can be up to 30 years or more. Eels from the river Imsa in Norway have been monitored since 1975 and this reference time-series has been used to assess the stock at the European level. Population dynamics in this catchment were analyzed during the late 1980s by estimating ages on whole cleared otoliths. However, techniques for revealing annual increments on otoliths have evolved over the years sometimes yielding significant differences in age estimates. In this study, the historical otolith data were reanalyzed using a grinding and polishing method rather than reading the whole otolith. The new age estimates were ... : See the manuscript for methods. ...