By Dr. Bjarte Bogstad
The Barents Sea, an Arctic shelf area north of Norway and Russia, is among the world’s richest fishing grounds, and its fish population is changing as the waters warm. Interest from the oil industry is increasing as well, setting up potential conflicts between oil exploration and fisheries. (See related interactive map: The Changing Arctic.
The Barents is home to the world’s largest stock of cod, with a sustainable catch of about 1 million tonnes (valued at about $2 billion) both for 2013 and 2014. This stock has increased considerably in recent years, both due to favorable environmental conditions and sensible management. Management of the fish resources in the Barents Sea has since 1976 been carried out through the Joint Norwegian-Russian Fisheries Commission. This joint management regime is generally considered to be successful, as most fish stocks in this area are now in a healthy state.
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In recent years, annual surveys conducted jointly by Norway and Russia have shown that cod are moving farther north and east than ever before*. These are stray individuals, but the main cod concentrations have also moved northwards in a similar way.
The northward migration of cod is a feeding migration: The cod follows its main prey, capelin—a small salmonid fish—and is able to follow it farther because of an increase in sea temperatures and decrease in ice cover. Cod is, however, not likely to cross the shelf-break and move further north into the deep Polar Ocean, as it is rarely found at depths larger than about 500 meters (1,640 feet). (Vote and comment: “Arctic Activity Is Ramping Up. What Do We Need to Know More About?“)
The conflict between the energy and fishing industries takes place especially in the spawning and nursery areas for fish. So far, the areas close to the main cod spawning grounds in Lofoten/Vesterålen have not been opened to oil exploration, but this has been a hot issue in Norwegian politics for several years.
So far, the recent changes to fish patterns are mostly occurring within feeding grounds: spawning areas and the general migration patterns between spawning, feeding and wintering areas are much more resistant to changes, both in the Barents Sea and elsewhere. Cod and most other major Barents Sea stocks spawn off the coast of Northern Norway, and so far, changes in spawning areas have been minor.
A considerable part of the fishery industry is at or near the spawning grounds, and due to fuel costs, and weather conditions, it is not likely that the fishing areas will change as much as the distribution of fish during the feeding migrations. The division of the quotas for cod and other major fish stocks in the Barents Sea between Norway and Russia has remained unchanged since the 1970s, despite variations in geographical distribution, so it would take a major change in distribution to re-open this issue.
Another stock which has expanded its geographical range northwards in recent years is the mackerel. This species prefers more temperate waters than do cod, but it has in recent years extended its range to the northwest and northeast, and is now found from the Bay of Biscay in the south to the east coast of Greenland in the northwest and the southern Barents Sea in the northeast. Mackerel was this year found in the Norwegian Sea as far north as 75° N.
The reasons for the northward expansion are the same as for cod – increased temperature (particularly in the surface layers where the mackerel is found) and increased stock size. Management of mackerel has proved more difficult than for cod, as the parties involved (The European Union, Norway, Faroes, and Iceland) have not reached an agreement on how to divide the catch quota between them. The stock has, however, so far been able to cope with catches higher than what is advised by the scientists. (Take the quiz: What You Don’t Know About Energy in the Changing Arctic.)
In the Barents Sea and other northern waters, such as those around Iceland and Greenland, there are large areas where fishing has been almost the only offshore activity going on, but where oil exploration could be moving in. As the fish stock changes along with the climate, these very rich fishing grounds will need continued monitoring and cooperation between fisheries and other industries seeking to enter the region.
* In 2012, cod was found as far north as 82° 30’ N 56° E (north of Franz Josef Land) and in 2013, as far east as 78° 30’ N 79° 30’ E (in the northern Kara Sea – and at the same longitude as India!).
Dr. Bjarte Bogstad is currently a senior scientist at Institute of Marine Research (IMR), Bergen, Norway, where he has been employed since 1988. IMR is Norway’s largest centre of marine science. Its main task is to provide advice to Norwegian authorities on aquaculture and the ecosystems of the Barents Sea, the Norwegian Sea, the North Sea and the Norwegian coastal zone. For this reason, about 50 percent of IMR’s activities are financed by the Ministry of Fisheries and Coastal Affairs.
His main fields of work have been modelling and assessment of the main commercial fish species in the Barents Sea, in particular cod and capelin, and how they interact with each other and how they are affected by other parts of the ecosystem as well as by climate. He has 38 publications in international scientific journals. Since 2010 Dr. Bogstad have chaired the Arctic Fisheries Working Group in ICES (International Council for the Exploration of the Seas). This group provides annual advice on harvesting of the cod, haddock, saithe, redfish, Greenland halibut and capelin in the Barents Sea and adjacent areas. The total catch of these species will in 2013 be about 1.6 million metric tonnes. He has for many years been strongly involved in the cooperation between IMR and the Russian marine research institute PINRO in Murmansk, and since 2010 he has participated in the Norwegian delegation to the Joint Norwegian-Russian Fisheries Commission. Dr. Bogstad’s education:
• M. Sc in applied mathematics (fluid dynamics), University of Bergen, 1986
• Ph. D in mathematics, University of Bergen, 1997. Thesis title: Multispecies models for the Barents Sea