Aarhus University Seal / Aarhus Universitets segl


of harbour seals and grey seals

Seals are shy animals that spend moste of their times submerged in the water. The best way to study their behavior, is by tagging them with a satellite tag. The tag gives away their gps position and scientist can follow their movement online. The transmitter have to be above the water to be able to transmit and it is therby most effective to place the transmitter on the head of the seal, because the seal often stick their head out of the water to breath. The transmitter can stay on the seal until May/June when the seals molt their fur.

Telemetry by satellite is the most common ways to track and monitor seal species. This tagging method helps us to better understand where seals fourage, how long they stay on land during the different seasons of the year and how they react to areas with heavy noise and reconstruction. Monitoring the seals by using satellite transmitters have already shown us that movement patterns variate between different species and ages. for scientist to get the best representable data, it is essential to track a larger number of individuals with different ages, during multiple years. In our sektion we take part in a couple of ongoing projekts with both grey seals and harbour seals. together, these information will provide a cleare picture of patterns and connections between behavior, movement and the spread of different diseases. 

More knowledge about seal fouraging patterns close to conventional fisheries, the spread of diseases and generel behavior, gives us a better opportunity to construct efficient conservation-strategies and initiatives in the future.

Seals in Streams - Limfjorden


Investigations of harbour seal in Limfjorden and Karup Å, and their impact on the Karup Å trout stock    

The harbour seal is most often found in the marine Danish waters, but is also frequently observed in rivers and streams across the northern hemisphere. Harbour seals naturally swim up freshwater streams in search for food. This has caused conflicts with anglers in particular, who experience a decreasing catch rate when there are seals present. The purpose of these studies is to investigate the harbour seals’ impact on the trout stock in Karup Å, through diet analysis from seals and mapping of seal occurrence and movement in the areas close to the stream. Two non-lethal mitigation methods, seal scarers and electrical fields, are investigated and evaluated for potential implementation: Seals in streams.

The scientific purpose

To investigate:

  • Seasonal variation in behavior
  • Movementpatterns
  • Fouraging areas
  • Resting areas and time spent on land
  • Effects from noise and environmental changes

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A harbour seal tagged on Anholt
Tagging a harbour seal at Anholt, Photo by AU
Tagged harbour seal
The tagged harbour seal is released photo by AU