Aarhus University Seal / Aarhus Universitets segl

No. 176: Seal's movement behavior patterns in the Limfjord and the surrounding streams

Teilmann, J., Stepien, E.N., Sveegaard, S., Dietz, R., Balle, J.D., Kyhn, L.A. & Galatius, A. 2020. Sælers bevægelsesadfærdsmønstre i Limfjorden og de omkringliggende åer. Analyser af adfærd af spættede sæler mærket med satellitsender i Limfjorden i relation til åer med havørredproduktion. Aarhus Universitet, DCE – Nationalt Center for Miljø og Energi, 28 s. - Teknisk rapport nr. 176. http://dce2.au.dk/pub/TR176.pdf

Summary

The harbour seal (Phoca vitulina, L 1758) is the most common Danish seal species and can be found in most Danish waters. It is frequently observed in rivers and streams all around the Northern Hemisphere. Harbour seals naturally swim up large freshwater streams in search for food. This has caused conflicts with anglers fishing for trout and salmon, as they report a decrease in catch rates when there are seals in the streams. This report investigates the movements of 10 tagged harbour seals in the Limfjord, following their movements in relation to the fresh water streams. The seals were tagged near Sundsøre Odde north of Karup Å, a large trout stream in northern Jutland, where seals have been observed foraging in the recent years. The movements were tracked using GPS positions. The tracks show that none of the 10 seals swims up the streams and rivers in Limfjorden. On the other hand, the seals spend a large part of the year in the narrow straits where fish pass by on their way to and from the Kattegat and the North Sea. It has not been determined yet what the seals eat and whether sea trout is an important prey item (will be reported in another report).