Marine mammals

The Belgian part of the North Sea (BNS) is part of the natural range of different species of mammals. There are two seal species, of which the harbor seal (Phoca vitulina) is the most abundant, but also the grey seal (Halichoerus grypus) is frequently seen. The harbour porpoise (Phocoena phocoena) lives from cetaceans both in the sea and in the rivers (distribution map). Other toothed whales such as white-beaked dolphins (Lagenorhynchus albirostris) and common bottlenose dolphins (Tursiops truncatus) are also often seen in the BNS (report MUMM 2017). The sighting of large whale species is rather exceptional. Finally, there are also several bat species along the coast and at sea: the common pipistrelle (Pipistrellus pipistrellus), the Nathusius' pipistrelle (Pipistrellus nathusii), the common noctule (Nyctalus noctula), the Serotine bat (Eptesicus serotinus), the parti-coloured bat (Vespertilio murinus) and the Daubenton's bat (Myotis daubentonii).

Marine mammals are legally protected in different ways. Every living and healthy animal belonging to the group of Cetacea (cetaceans) and Pinnipedia (seals) must be reported in case of incidental capture and released again (Marine Environment Act - h3-article 13). If the captured animal is injured, a rescue procedure must be started. The harbour seal and harbour porpoise are also listed as protected species in Appendix II of the Habitat Directive. Finally, the hunting of marine mammals is prohibited by the Marine Environment Protection Act (Marine Environment Act - h3-article 12.1). Nevertheless, marine mammals are still burdened by human activities at sea (fishing, dredging, construction of offshore structures and oil and gas extraction), where noise pollution, for example, can influence the communication behaviour of cetaceans (Haelters et al., 2012).

The presence of mammals on the coast and in the sea is investigated in various ways. On marinemammals.be you can find data from observations and strandings of marine mammals over the past 20 years. Information on the health status of the animal is obtained through an autopsy of washed up carcasses. Every summer, these cetaceans are observed by ships and aircraft counts, as part of the SCAN-III project. OD Nature carries out additional aerial counts in spring and winter. On the other hand, the echolocation sounds of porpoises and dolphins are recorded by C-POD hydrophones in the LifeWatch passive acoustic network. These hydrophones are distributed in the BNS, and OD Nature also uses C-PODs to map the impact of the offshore wind farms on marine mammals. On the LifeWatch data explorer you can work with this data yourself. The echolocation calls of bats are also measured in the BatCorder netwerk along the Belgian coast. These measurements are available in the LifeWatch data explorer and make it possible to distinguish between species and even behaviour. Finally, migrating bats, equipped with a small transmitter, are also monitored via radio telemetry in the Motus netwerk with two stations in Belgium.