The Skagerrak (, , ) is a

strait A strait is an oceanic landform connecting two seas or two other large areas of water. The surface water generally flows at the same elevation on both sides and through the strait in either direction. Most commonly, it is a narrow ocean channe ...

running between the Jutland peninsula of Denmark, the southeast coast of Norway and the west coast of

Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic country located on ...

, connecting the North Sea and the Kattegat sea area through the Danish Straits to the Baltic Sea. The Skagerrak contains some of the busiest shipping routes in the world, with vessels from every corner of the globe. It also supports an intensive fishing industry. The ecosystem is strained and negatively affected by direct human activities. Oslo and

Gothenburg Gothenburg (; abbreviated Gbg; sv, Göteborg ) is the second-largest city in Sweden, fifth-largest in the Nordic countries, and capital of the Västra Götaland County. It is situated by the Kattegat, on the west coast of Sweden, and has ...

are the only large cities in the Skagerrak region.

Name

The meaning of ''Skagerrak'' is most likely the Skagen Channel/Strait. Skagen is a town near the northern cape of Denmark (The Skaw). ''Rak'' means 'straight waterway' (compare the Damrak in Amsterdam); it is cognate with ''

reach Reach or REACH may refer to: Companies and organizations * Reach plc, formerly Trinity Mirror, large British newspaper, magazine, and digital publisher * Reach Canada, an NGO in Canada * Reach Limited, an Asia Pacific cable network company * ...

''.Nudansk Ordbog (1993), 15th edition, 2nd reprint, Copenhagen: Politikens Forlag, entry ''Skagerrak''. The ultimate source of this syllable is the Proto-Indo-European root *reg-, 'straight'. ''Rak'' means 'straight' as in 'straight ahead' in modern Norwegian and Swedish. ''Råk'' in both modern Norwegian and Swedish refers to a channel or opening of water in an otherwise ice-covered body of water. There is no evidence to suggest a connection with the modern Danish word ''rak'' (meaning rabble or riff-raff). Another possibility is that the Skagerrak was named by Dutch seafarers, in the same way the adjacent Kattegat got its name. It was quite common for the Dutch to call similar stretches of waterways a ''rak'', such as: Langerak, Damrak, Gouderak, and Tuikwerderrak. (See Kattegat for its etymology, in which ''gat'' means "gate" or "hole".)

Geography

The Skagerrak is long and between wide. It deepens toward the Norwegian coast, reaching over 700 m at the Norwegian Trench. Some ports along the Skagerrak are Oslo,

Larvik Larvik () is a List of cities in Norway, town and Municipalities of Norway, municipality in Vestfold in Vestfold og Telemark Counties of Norway, county, Norway. The administrative centre of the municipality is the city of Larvik. The municipality ...

and Kristiansand in Norway, Skagen, Hirtshals and Hanstholm in Denmark and Uddevalla,

Lysekil Lysekil () is a Urban areas in Sweden, locality and the seat of Lysekil Municipality in Västra Götaland County, Sweden. It had about 7,600 inhabitants in 2018. Situated on the south tip of Stångenäs peninsula at the mouth of Gullmarn fjord, it ...

and Strömstad in

. The Skagerrak has an average

salinity Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...

of 80 practical salinity units, which is very low, close to that of brackish water, but comparable to most other coastal waters. The area available to biomass is about and includes a wide variety of habitats, from shallow sandy and stony reefs in Sweden and Denmark to the depths of the Norwegian trench.

Extent

The International Hydrographic Organization defines the limits of the Skagerrak as follows:

''On the West.'' A line joining Hanstholm () and the Naze ( Lindesnes, ). ''On the Southeast.'' The Northern limit of the Kattegat Skagen (The Skaw, North Point of Denmark) and Paternosterskären () and thence Northeastward through the shoals to Tjörn Island">Tjörn Municipality">Tjörn Island/nowiki>.

History

Older names for the combined Skagerrak and Kattegat were the ''Norwegian Sea'' or ''Jutland Sea''; the latter appears in the Knýtlinga saga. Until the construction of the Eider Canal in 1784 (a predecessor to the Kiel Canal), Skagerrak was the only way in and out of the Baltic Sea. For this reason the strait has had a busy international traffic for centuries. After the Industrial Revolution, the traffic increased and today Skagerrak is among the busiest straits in the world. In 1862, a short cut, the

Thyborøn Channel Thyborøn is a fishing village in Jutland, Denmark with a population of 1,890 (1 January 2022),Limfjord was constructed in Denmark through Skagerrak from the North Sea by going directly to the Kattegat. The Limfjord supports only minor transports though. In both world wars, the Skagerrak was strategically very important for Germany. The biggest sea battle of the First World War, the

Battle of Jutland The Battle of Jutland (german: Skagerrakschlacht, the Battle of the Skagerrak) was a naval battle fought between Britain's Royal Navy Grand Fleet, under Admiral John Jellicoe, 1st Earl Jellicoe, Sir John Jellicoe, and the Imperial German Navy ...

, also known as the Battle of the Skagerrak, took place here May 31 to June 1, 1916. In the Second World War, the importance of controlling this waterway, the only sea access to the Baltic, was the motive for the German invasions of Denmark, Norway and the construction of the northern parts of the

Atlantic Wall The Atlantic Wall (german: link=no, Atlantikwall) was an extensive system of coastal defences and fortifications built by Nazi Germany between 1942 and 1944 along the coast of continental Europe and Scandinavia as a defence against an anticip ...

. Both of these naval engagements have contributed to the large number of shipwrecks in the Skagerrak.

Traffic and industry

Skagerrak is a heavily trafficated strait, with c. 7,500 individual vessels (excluding fishing vessels) from all over the world visiting in 2013 alone.

Cargo ship A cargo ship or freighter is a merchant ship that carries cargo, goods, and materials from one port to another. Thousands of cargo carriers ply the world's seas and oceans each year, handling the bulk of international trade. Cargo ships are usu ...

s are by far the most common vessel in Skagerrak at c. 4,000 individual ships in 2013, followed by

tanker Tanker may refer to: Transportation * Tanker, a tank crewman (US) * Tanker (ship), a ship designed to carry bulk liquids ** Chemical tanker, a type of tanker designed to transport chemicals in bulk ** Oil tanker, also known as a petroleum ta ...

s, which are nearly half as frequent. When viewed in combination with the Baltic Sea area, ships from 122 different nationalities visited in 2013, with most of these carrying cargo or passengers within Europe, regardless of their flag state. Nearly all commercial vessels in Skagerrak are tracked by the Automatic Identification System (AIS).

Recreation

Skagerrak is popular for recreational activities in all three countries. There are many summer house residences and several marinas along the coasts.

Biology

The Skagerrak is habitat for approximately 2,000 marine species, many of them adapted to its waters. For example, a variety of Atlantic cod called the Skagerrak cod spawns off the Norwegian coast. The eggs are buoyant and the hatchlings feed on zooplankton. Juveniles sink to the bottom where they have a shorter maturity cycle (2 years). They do not migrate but remain local to Norwegian fjords. The variety of habitats and the large volume of plankton on the surface support prolific marine life. Energy moves from the top to the bottom according to

Vinogradov Vinogradov or Vinogradoff (russian: Виногра́дов) is a common Russian last name derived from the Russian word виноград (''vinograd'', meaning "grape" and виноградник ''vinogradnik'', meaning "vineyard"). Vinogradova (ru ...

's ladder of migrations; that is, some species are

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

and others pelagic, but there are graded marine layers within which species move vertically for short distances. In addition, some species are benthopelagic, moving between surface and bottom. The benthic species include ''

Coryphaenoides rupestris ''Coryphaenoides rupestris'' is a species of marine ray-finned fish in the family Macrouridae. Its common names include the rock grenadier, the roundnose grenadier and the roundhead rat-tail. In France it is known as ''grenadier de roche'' and in ...

'', ''

Argentina silus The greater argentine (''Argentina silus'' ; synonymous with ''Salmo silus''), also known as the Atlantic argentine, great silver smelt, herring smelt or simply smelt, is a northern Atlantic Ocean, Atlantic herring smelt and can be found at dep ...

'', '' Etmopterus spinax'', '' Chimaera monstrosa'' and '' Glyptocephalus cynoglossus''. On the top are '' Clupea harengus'', '' Scomber scombrus'', '' Sprattus sprattus''. Some species that move between are '' Pandalus borealis'', '' Sabinea sarsi'', '' Etmopterus spinax''.

Reefs

Apart from sandy and stony reefs, extensive cold water coral reefs, mostly of '' Lophelia'', are growing in Skagerrak. The Säcken Reef in the Swedish marine protection of Koster Fjord is an ancient cold water coral reef and the only known coral reef in the country. The Tisler Reef in the Norwegian marine protection of

Ytre Hvaler National Park Ytre Hvaler National Park ( no, Ytre Hvaler nasjonalpark, literally ''Outer Hvaler National Park'') is a national park located within the municipalities of Hvaler and Fredrikstad in Østfold, Norway. The park was established on 26 June 2009 and w ...

is the largest known coral reef in Europe. Lophelia reefs are also present in the Norwegian trench and they are known from the shallow waters of many Norwegian fjords. Skagerrak also holds a number of rare

bubble reef A cold seep (sometimes called a cold vent) is an area of the ocean floor where hydrogen sulfide, methane and other hydrocarbon-rich fluid seepage occurs, often in the form of a brine pool. ''Cold'' does not mean that the temperature of the seep ...

s; biological reefs formed around cold seeps of geological carbohydrate outgassings, usually methane. These rare habitats are mostly known from the Danish waters of Skagerrak west of Hirtshals, but more might be discovered in future surveys. Bubbly reefs are very rare in Europe and supports a very varied ecosystem. With the centuries long heavy international seatraffic of Skagerrak, the seabed also holds an abundance of shipwrecks. Wrecks on shallow waters, provides a firm anchoring for several corals and polyps and explored wrecks have been revealed to support Dead Man's Fingers corals, Brittle stars and large wolffish. A 2020 seafloor mapping project around Jammerbugten in Skaggerak, ran by danish explorer

Klaus Thymann Klaus Thymann (born 1974) is a Danish explorer, scientist, fellow at the Royal Geographical Society, photographer, filmmaker and creative director based in London, United Kingdom. He has developed an original viewpoint utilising a cross-discipli ...

, found evidence of much greater biodiversity in a range seafloor habitats previously thought to be sandy with a low density of wildlife. Dead Man’s Fingers corals were again among the species documented for the first time in these coastal habitats.

Environmental concerns

Scientists and environmental institutions have expressed concern about the increasing pressure on the ecosystem in Skagerrak. The pressure has already had negative impacts and is caused by cumulative environmental effects, of which direct human activities are only one piece of the puzzle. Climate change and ocean acidification are expected to have increasing impacts on the Skagerrak ecosystem in the future. Skagerrak and the North Sea receives considerable inputs of

hazardous material Dangerous goods, abbreviated DG, are substances that when transported are a risk to health, safety, property or the environment. Certain dangerous goods that pose risks even when not being transported are known as hazardous materials ( syllabi ...

and radioactive substances. Most is ascribed to long-range transport from other countries, but not all. Marine litter is also a growing problem. Until recently, waste water and sewage pouring into Skagerrak from settlements and industries was not treated at all. In combination with wash out of excessive nutrients from conventional farming, this has often led to large algae blooms.

Protections

There are several marine protections in Skagerrak, including: ;Norway *

, established on 26 June 2009 *

Raet National Park Raet National Park ( no, Raet nasjonalpark) is a national park in Arendal, Tvedestrand and Grimstad in Agder, southeastern Norway. It is mostly a marine park, and includes some islands and coastal areas. Raet covers an area of , of which is sea ...

, established on 16 December 2016 ;Sweden * Kosterhavet National Park * Bratten, a newly designated

Natura 2000 Natura 2000 is a network of nature protection areas in the territory of the European Union. It is made up of Special Areas of Conservation and Special Protection Areas designated under the Habitats Directive and the Birds Directive, respectively ...

sea area beyond Kosterhavet. Pockmarks and

biogenic reef A biogenic substance is a product made by or of life forms. While the term originally was specific to metabolite compounds that had toxic effects on other organisms, it has developed to encompass any constituents, secretions, and metabolites of ...

s at depths of . *

Gullmarsfjorden Gullmarn, also known as Gullmarsfjorden or Gullmaren, is a threshold fjord in the middle of Bohuslän Archipelago on the west coast of Sweden. It is the largest of the Bohuslän fjords with a length of and a width ranging from . At its mouth, t ...

, Sweden's first marine conservation area from 1983. ;Denmark * Grenen and a sea area immediately north.

Notes and references

External links

The Baltic Sea, Kattegat and Skagerrak
Swedish Meteorological and Hydrological Institute (SMHI).
Skagerrak Deep-water Fish Assemblage

Marine vessel Traffic {{Authority control Denmark–Sweden border International straits Landforms of Västra Götaland County Norway–Sweden border Straits of Denmark Straits of Norway Straits of Sweden