Strandings of cetaceans in Belgium from 1995 to 2017
It is a tradition that regular overviews are published of strandings of cetaceans. The last overviews for Belgium covered the period 1975 to 1989 and 1990 to 1994. This overview deals with strandings between 1995 and 2017. Along the short Belgian coastline, and in Belgian marine and inland waters, 1401 dead or dying cetaceans of twelve species were found between 1995 and 2017. Most of these (n=1364) were harbour porpoises (Phocoena phocoena), a species that made a remarkable return to the southern North Sea after a virtual absence since the 1950s. Numbers of stranded harbour porpoises quickly rose since the end of the 1990s, and have remained relatively high since then, with on average almost 100 strandings per year between 2005 and 2017. The only other species currently considered as indigenous to the southern North Sea is the white-beaked dolphin (Lagenorhynchus albirostris), with 17 records of dead animals in Belgium between 1995 and 2017. Between 1995 and 2017, also a number of species not indigenous to the southern North Sea, or having become extirpated in this area, were recorded. This was the case for Atlantic white-sided dolphin (Lagenorhynchus acutus) (n=1), bottlenose dolphin (Tursiops truncatus) (2), common dolphin (Delphinus delphis) (2), striped dolphin (Stenella coeruleoalba) (1), long-finned pilot whale (Globicephala melas) (1), narwhal (Monodon monoceros) (1), sperm whale (Physeter macrocephalus) (2), minke whale (Balaenoptera acutorostrata) (3), humpback whale (Megaptera novaeangliae) (1), fin whale (Balaenoptera physalus) (5) and an unidentified dolphin. The two washed ashore bottlenose dolphins, as well as the pilot whale and one of the common dolphins, had probably drifted in from distant areas. Two of the fin whales were brought to port on the bow of an ocean-going vessel, while two other cases concerned finds of recent lower jaws. The stranding of a narwhal was by far the most remarkable one: of this Arctic species only ten stranding records are known for the whole of the North Sea. During the period considered, identified anthropogenic causes of death were incidental catch, ship collision and plastic ingestion.