North Sea - Ecology

A total of 224 fish species have been recorded from the North Sea. These species originate from three zoogeographical regions: 66 species are of Boreal (northern) origin, 110 species are Lusitanian (southern) and 48 species are Atlantic. Knijn et al. (1993) provides a description of the abundance and distribution of many of them. Diversity is lower in the shallow southern North Sea and eastern Channel (Rogers et al., 1998). Inshore, where there is more variation in sediment types and a higher level of spatial patchiness, the species diversity is generally higher (Greenstreet and Hall, 1996).

There are 31 species of seabirds breeding along the coasts of the North Sea, with the major seabird colonies located on the rocky coasts in the northern part of the North Sea. Approximately 10 million seabirds are present at most times of the year, but seasonal shifts and migrations are distinct (OSPAR, 2000).

Two species of seal are regularly observed and breed in the North Sea, the grey seal (Halichoerus grypus) and the harbour seal (Phoca vitulina). The grey seal is most abundant in exposed locations in the northwest, while the harbour seal is more widespread, preferring mud and sand flats.

There are sixteen species of cetacean regularly seen in the North Sea, the most frequently observed cetacean is the harbour porpoise (Phocoena phocoena). Other species of toothed cetacean that are sighted regularly include long-finned pilot whales (Globicephala melas), the common dolphin (Delphinus delphis), the whitesided dolphin (Lagenorhynchus acutus), Risso’s dolphin (Grampus griseus) and the killer whale (Orcinus orca) (OSPAR, 2000).