Biology of Coastal European Eel (Anguilla anguilla) in Norway: Growth Analysis and Temporal Variation in Abundance

• Main Author: Sæth, Linn Stenersen
• Format: Master Thesis
• Language: English
• Published: 2023
• Subjects: Norway; Anguilla anguilla; European eel
• Online Access: http://hdl.handle.net/10852/104299

The European eel has a complex life history. They are widely distributed in Europe and northern Africa, but panmictic, meaning that co-management across the entire distributional range is of vital importance. In Norway, eel fishing has been banned since 2010, but a small scientific fishery operated by the Institute of Marine Research started in 2016 to monitor the species. The monitoring plan is divided in two: mark-recapture experiments in Austevoll, Norway, and analyses of commercial fishery data from fishers in Norway that have been granted special permission to fish eel during certain parts of the year. The data from these two ongoing time series are the basis of my master’s thesis. Mark-recapture data was used to investigate body growth of eel marked with Passive Integrated Transponder tags. Mean annual growth rates in Austevoll were found to be 14 mm/year, with a large difference in growth between individuals. Growth was investigated according to different body lengths and temperature, and there was a slight tendency that showed smaller eel had higher growth rates than large eel, and that eel grow faster at higher temperatures. Both mark-recapture data and commercial fisher data were used to investigate abundance of eel over time. No general patterns in abundance between years was found when comparing population estimates for Austevoll and Catch Per Unit Effort estimates for both Austevoll and fisher data. However, the results of the mark-recapture experiment did indicate a strong seasonal difference in eel abundance, with higher abundance in the warmer summer months, and lower in the late fall, when temperatures in the area are colder. From the fisher data, it was found that when analyzing Catch Per Unit Effort the eel abundance was significantly higher in Southern Norway, compared to Western and Eastern Norway. Overall, the results from the seven years of eel monitoring in Norway showed similar patterns as previous studies on eel growth and seasonal variations in abundance, but no clear patterns in the ...