Norwegian Sea Drainages
Svein Jakob Saltveit (The Freshwater Ecology & Inland Fisheries Laboratory (LFI), Natural History Museum, University of Oslo)
Major Habitat Type
Drainages flowing into
North Sea, Norwegian Sea, Atlantic Ocean
Main rivers to other water bodies
Rivers in the ecoregion include the rivers Tovdalelva, Otra, Mandalselva, Kvina, Bjerkreim, Suldalslågen, Etne, Lærdalselva, Nausta, Jostedøla, Stryn, Orkla, Gaula, Stjørdal, Namsen and Vefsna. There are also numerous fjords, including Sognefjord, the second deepest and longest fjord in the world. Other fjords include Boknafjord, Hardangerfjord, Nordfjord, Trondheimsfjord, and Bjørnafjord. Jostedalsbreen is the largest glacier in continental Europe. Lakes, most of which were formed by glacial erosion, are some of the deepest in Europe, including Hornindalsvatnet (514 m) and Salsvatnet (464 m).
This ecoregion encompasses the western coastal drainages of the Scandinavian Peninsula, from Langesund fjord on the southeast coast of Norway up to the Lyngen fjord east of Tromsø. It is bordered to the north and east by the Northern Baltic Drainages , to the south by the Skagerrak Strait, and to the west by the North Sea and Norwegian Sea. It is almost entirely within Norway.
The Scandinavian Mountains that run along the length of the Scandinavian Peninsula were formed during the Caledonian orogeny by tectonic action that pushed the Baltic shield against the Greenland plate. Later, glaciations during the Quaternary period further shaped the landscape through the formation of fjords, valleys, glacier lakes, fluvial sediments, and exposed Precambrian bedrock of granite and gneiss. Altitudes range from sea level to more than 2400 m asl at Store Skagastølstind, the third highest peak in Norway. The dramatic relief includes deeply cut fjords, with altitudes that may rise more than 1100 m less than 1 km from the sea (L’Abée-Lund et al. 2009).
The ecoregion includes watersheds from coastal rivers that have moderate gradients and low discharges (<5 m3/s), rivers with high gradients and moderate discharge (20-40 m3/s), and low gradient rivers with high discharges (>100 m3/s) (L’Abée-Lund et al. 2009). Most rivers have headwater lakes, some of which are glacial-fed. Some headwater lakes are hydropower reservoirs, thus affecting the river flow regime. Southeastern, some central, and northern watersheds are generally larger, with high discharges and long stretches with low gradients. Flow is determined primarily by snowmelt and rainfall, with peak flow in spring and autumn. The rivers Mandalselva and Otra, for example, feed in the mountain area Setesdalsheiene, emptying into the Skagerrak Strait with a discharge averaging 83 m3/s and 150 m3/s, respectively, at their mouths. They are characterized by both high and low gradients within short reaches. The high gradient rivers are mainly found on the west and southwest coasts. Here, rainfall is abundant and in spite of small watersheds, some have high discharges. The Suldalslågen River, for example, flows through a wide valley and is characterized by waterfalls, rapids, and gentler sections. Before regulation its mean annual discharge was 108 m3/s. The river Lærdalselva flows into the Sognefjord with a mean annual discharge of 36 m3/s. North of Sognefjord is the Jostedøla River, which is fed by eleven glacial arms of the Jostedalsbreen glacier. It is characterized by many waterfalls and rapids in its upper section, although they still occur downstream despite the lower gradient. It has a mean annual discharge at its mouth of 60 m3/s. In the central parts the Orkla River flows through rapids and waterfalls in the upper catchment and gently meanders in the lower catchment, emptying into the Trondheimsfjord with a mean annual discharge of 67 m3/s. Further north is the Namsen River, which flows into the Atlantic Ocean with a mean annual discharge of 304 m3/s (L’Abée-Lund et al. 2009).
Ramsar sites in the ecoregion include (from north to south): Balsfjord wetland system, Skogvoll, Karlsøyvær, Bliksvær, Øvre Forra, Tautra & Svaet, Froan Nature Reserve, Ørlandet, Havmyran, Sandblåst-/Gaustadvågen Nature Reserve, Harøya wetlands system, Giske wetlands system, Jæren wetland system, and Lista wetlands system (Wetlands International 2002).
Several terrestrial ecoregions occur throughout the Norwegian Sea drainages due to the wide variation in latitude. Natural pine forests occur, for example, around Bergen and Stavanger as well as on the Lofoten Islands where winters are fairly mild and precipitation is high. Sitka spruce (Picea sitchensis) has been introduced and is found throughout the whole ecoregion. The upper forest limit for Scots pine (Pinus sylvestris) and mountain birch (Betula pubescens) occurs in the central parts of this ecoregion between 1050 m asl to 1200 m asl, respectively, but lower on the southwest coast between 700 and 930 m asl, respectively. At higher elevations throughout most of the southern and northern part of the ecoregion the Scandinavian montane birch forest and grasslands occur. Another characteristic species is Norway spruce (Picea abies), especially to the east. The Scandinavian and Russian taiga extends from northern Europe to the west coast of Norway along lower lying areas such as the Rauma and Namdalen valleys. It is dominated by species such as Scots pine. The western extent of the Sarmatic mixed forests occurs along the Skagerrak coast in Norway, and include species such as English oak (Quercus robur), Norway spruce, and Scots pine (WWF 2001).
Description of endemic fishes
The ecoregion contains no endemic fish species.
Other noteworthy fishes
Atlantic salmon (Salmo salar) and brown trout (S. trutta) are the most economically important species in the Norwegian Sea drainages.
Rivers like Suldalslågen,Lærdalselva, Gaula and Namsen are well known for their sport fishing for Atlantic salmon and anadromous brown trout. Some, Suldalslågen and Eira, also were famous for their large sized salmon (> 30 kg) before river regulation.
Justification for delineation
Northern European ecoregions were delineated through a top-down process using major basins as a starting point and incorporating traditionally recognized zoogeographic patterns where appropriate (Abell et al. 2008).
Level of taxonomic exploration
- Abell, Robin,M.L. Thieme,C. Revenga,M. Bryer,M. Kottelat,N. Bogutskaya,B. Coad,N. Mandrak,S.C. Balderas,W. Bussing,M.L.J. Stiassny,P. Skelton,G.R. Allen,P. Unmack,A. Naseka,R. Ng,N. Sindorf,J. Robertson,E. Armijo,J.V. Higgins,T.J. Heibel,E. Wikramanayake, (2008). "Freshwater Ecoregions of the World: A New Map of Biogeographic Units for Freshwater Biodiversity Conservation" BioScience 58 (5) pp. 403-414.
- Abée-Lund, J.H.,J.A. Eie,P.E. Faugli,S. Haugland,N.A. Hvidsten,A.J. Jensen,K. Melvold,V. Pettersen,L.E. Pettersen;S.J. Saltveit (2009). "Rivers of the Boreal uplands" Tockner, K.;U. Uehlinger;C.T. Robinson (Ed.) Rivers of Europe ( pp. Pp 577-606 ) London, UK: Academic Press.
- Delany, S.,Scott, D.,Dodman, T.;Stroud, D., (eds) (2009). "An atlas of wader populations in Africa and Western Eurasia" Wageningen, The Netherlands: Wetlands International.
- Hijmans, R. J., S. Cameron and Parra., J. (2004) \WorldClim, Version 1.4 (release 3). A square kilometer resolution database of global terrestrial surface climate\ "<"[http://www.worldclim.org]">" (16 July 2009)
- Kottelat, M.;Freyhof, J. (2007). "Handbook of European Freshwater Fishes" Cornol, Switzerland: Publications Kottelat.
- Peel, M. C., Finlayson, B. L. and McMahon, T. A. (2007). "Updated world map of the Köppen-Geiger climate classification" Hydrology and Earth System Sciences 11 pp. 1633–1644.
- Wetlands International (2002) \Ramsar Sites Database: A directory of wetlands of international importance\ "<"http://ramsar.wetlands.org/">" (2003)
- World Wildlife Fund (WWF) (2001) \Terrestrial Ecoregions of the World\ "<"http://www.worldwildlife.org/wildworld/profiles/terrestrial_nt.html">"