Aarhus University Seal

Novana - Marine monitoring

The national surveillance program for the aquatic environment and nature

NOVANA is a collaboration between the Danish Nature Agency and the Danish Centre for Environment and Energy at Aarhus University. Each year, a scientific report on the marine areas in Denmark is prepared, which includes the surveillance of marine mammals.

The latest NOVANA publications can be seen at the Marine Topic, Centre's website, where the latest report from the marine program, in which the results on marine mammals are shown, can also be found.

Seals go ashore to rest, moult and give birth. Surveillance of seals is therefore conducted by plane, from which high-quality images are taken while the seals rest on land. The seals are then counted from these images. Surveillance of adult seals is conducted in the seals' moulting periods, when the seals spend much time on land. From the images, the size and development of the population are assessed. During the seals’ reproduction period, the pups are born at the breeding grounds, and the annual production of pups is estimated. Our two seal species, grey seal and harbour seal, have different breeding and moulting periods, so seal surveillance is conducted throughout most of the year.

Danish waters have three genetically separate populations of harbour porpoises (1. The North Sea/Skagerrak, 2. The Belt Sea and 3. The Baltic Sea), and they are monitored separately. Monitoring focuses on the 16 Habitat Areas (SACs = Sites of Community Importance) designated for harbour porpoises, but also includes the total area of the populations. Thus, in the five SACs in the North Sea and Skagerrak, porpoises are counted by plane every summer. In six SACs in the inner Danish waters, acoustic listening stations are deployed that can provide information on variations between seasons and years, and this population is also counted from a ship or plane every six years. The waters around Bornholm (the Baltic Sea population) are also monitored using acoustic listening stations.