The Skagerrak contains some of the busiestshipping routes in the world, with vessels from every corner of the globe. It also supports an intensive fishing industry.[1] The ecosystem is strained and negatively affected by direct human activities.Oslo andGothenburg are the only large cities in the Skagerrak region.
The strait is likely named afterSkagen, a town near the northern cape of Denmark, with 'Rak' meaning 'straight waterway'. The Skagerrak is 240 km long and 80–140 km wide, deepening towards the Norwegian coast. It has an average salinity comparable to other coastal waters, housing a variety of habitats.
Historically, the Skagerrak was the only access to theBaltic Sea until the construction of theEider Canal in 1784. During both World Wars, the strait held strategic importance for Germany. Presently, it remains one of the busiest straits worldwide.
The Skagerrak is a habitat for approximately 2,000 marine species, including a unique variety of Atlantic cod. It also contains sandy and stony reefs and cold-water coral reefs. Environmental institutions have expressed concern about increasing pressure on the ecosystem due to human activities and climate change. Protections are in place, with severalmarine protected areas in Skagerrak, includingYtre Hvaler National Park in Norway andKosterhavet National Park in Sweden.
The meaning ofSkagerrak is most likely the Skagen Channel/Strait.Skagen is a town near the northern cape of Denmark (The Skaw). InDutch,rak means 'straightwaterway', as seen in Dutchhydronyms such asDamrak,Gouderak,Langerak, Tuikwerderrak, andVolkerak), cognate withreach.[2][3] The ultimate source of this syllable is theProto-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 wordrak (meaning rabble or riff-raff). It is therefore likely that the Skagerrak was named by Dutch seafarers, as was the adjacentKattegat.
The area available to biomass is about 3,600 km2 (1,400 sq mi) and includes a wide variety of habitats, from shallow sandy and stonyreefs in Sweden and Denmark to the depths of theNorwegian trench.
German bunkers from World War II are still present along the coasts of Skagerrak. (Kjærsgård Strand in Denmark)
Older names for the combined Skagerrak andKattegat were theNorwegian Sea orJutland Sea; the latter appears in theKnýtlinga saga.
Until the construction of theEider Canal in 1784 (a predecessor to theKiel Canal), Skagerrak was the only way in and out of theBaltic Sea. For this reason, the strait has had busy international traffic for centuries. After theIndustrial Revolution, the traffic increased and today Skagerrak is among the busiest straits in the world. In 1862, a short cut, theThyborøn Channel at theLimfjord was constructed in Denmark through Skagerrak from the North Sea by going directly to theKattegat. The Limfjord supports only minor transports though.
In both world wars, the Skagerrak was strategically very important for Germany. The biggest sea battle of theFirst World War, theBattle of Jutland, also known as the Battle of the Skagerrak, took place here May 31 to June 1, 1916. In theSecond World War, the importance of controlling this waterway, the only sea access to the Baltic, was the motive for theGerman invasions of Denmark andNorway as well as the construction of the northern parts of theAtlantic Wall. Both of these naval engagements have contributed to the large number of shipwrecks in the Skagerrak.
Skagerrak is a busy shipping lane, with c. 7,500 individual vessels (excluding fishing vessels) from all over the world visiting in 2013 alone.Cargo ships are by far the most common vessel in Skagerrak at c. 4,000 individual ships in 2013, followed bytankers, 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 theirflag state.[5]
The Skagerrak is habitat for approximately 2,000 marine species, many of them adapted to its waters. For example, a variety ofAtlantic cod called the Skagerrak cod spawns off the Norwegian coast. The eggs are buoyant and the hatchlings feed onzooplankton. Juveniles sink to the bottom where they have a shorter maturity cycle (2 years). They do not migrate but remain local to Norwegianfjords.
Apart from sandy and stony reefs, extensive cold watercoral reefs, mostly ofLophelia, are growing in Skagerrak. The Säcken Reef in the Swedish marine protection ofKoster 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 ofYtre Hvaler National Park 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.[7][8]
Skagerrak also holds a number of rarebubbling reefs; biological reefs formed around cold seeps of geological carbohydrate outgassings, usuallymethane. These rare habitats are mostly known from the Danish waters of Skagerrak west ofHirtshals, but more might be discovered in future surveys.[9] Bubbling 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 supportDead Man's Fingers corals,Brittle stars and largewolffish.[10] A 2020 seafloor mapping project[11] around Jammerbugten in Skaggerak, ran by Danish explorerKlaus Thymann, 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.
Scientists and environmental institutions have expressed concern about the increasing pressure on theecosystem 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 andocean acidification are expected to have increasing impacts on the Skagerrak ecosystem in the future.[1]
Skagerrak and the North Sea receives considerable inputs ofhazardous material andradioactive substances. Most is ascribed to long-range transport from other countries, but not all.[12]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 fromconventional farming, this has often led to largealgae blooms.[13]
Bratten, a newly designated 120,878.4-hectare (298,697-acre)Natura 2000 sea area beyond Kosterhavet.Pockmarks andbiogenic reefs at depths of 200–500 metres (660–1,640 ft).
Gullmarsfjorden, Sweden's first marine conservation area from 1983.
Denmark
Grenen and a 270,295-hectare (667,910-acre) sea area immediately north.[15]
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