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The North Sea and Skagerrak

Økosystemtokt Nordsjøen Skagerak

"Johan Hjort" on an ecosystem survey in the North Sea and Skagerrak.

Photo: Jørgen Ree Wig / Havforskningsinstituttet

The North Sea is the shallowest of our seas: two thirds of it is less than one hundred metres deep.

The ecosystem here is also different from the Barents Sea and Norwegian Sea. The North Sea is much more heavily influenced by us: it is one of the world’s most heavily trafficked seas with big ports, large-scale fisheries, oil and gas extraction, sand and gravel dredging, and the dumping of earth. Around 184 million people live in the drainage basins that feed the North Sea. The ecosystem is affected by emissions from buildings, agriculture and industry.

The North Sea can be split into four main areas:

  • The north, where the depth ranges between 100 and 200 metres, is where the most important habitats for Norwegian fisheries are found. This is where adult cod, saithe, herring, haddock and Norway pout are harvested.
  • In the Norwegian Trench, which is the deepest part of the North Sea at up to 700 metres deep, we find deep-sea species such as the herring smelt, roundnose grenadier and velvet belly lanternshark.
  • Fish are generally less abundant in the central part of the North Sea than further north.
  • Skagerrak in the east, which is 50-100 metres deep, is home to nursery habitats for herring and cod. This area is also important to sandeel, as well as being the main habitat for flatfish.