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Researcher Maria Fossheim (left) at IMR and Associate Professor Raul Primicerio UiT Norway's Arctic University have found that fish communities in the Barents Sea are  pushed northwards by climate change. The study was published in Nature Climate Change yesterday. Researchers from the Institute of Marine Research (IMR), UiT - The Arctic University of Norway and from the Russian marine research institute PINRO have also contributed to the scientific article. One of them is vice dean Michaela Aschan (right) at the Faculty of Biosciences, Fisheries and Economics at UiT - The Arctic University of Norway.
Photo: Gunnar Sætra
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Climate change pushing fish northwards

Chronicle in Aftenposten Viten: A new study shows that fish communities in the Barents Sea are moving up to four times faster than the Intergovernmental Panel on Climate Change (IPCC) estimates.

Global warming is causing the ocean temperature to rise, but this increase is not evenly distributed across the globe. In our waters, the sea temperature is increasing twice as fast as the global average.

 

In the period 2004-2012, the seabed temperature in the Barents Sea increased by almost 1 °C. This has an impact on all organisms living in the sea.

Fish moving northwards

On May 18th this year we published an article in Nature Climate Change along with colleagues from the Institute of Marine Research, the University of Tromso and the Russian Research Institute of Marine Fisheries and Oceanography (PINRO). Each year since 2004, Norwegian and Russian marine scientists have been at sea when the summer is on the wane and the sea ice coverage in the northern Barents Sea is at its lowest. Consequently, we can demonstrate that southern fish communities are gradually moving northwards.

In this fish community we find species including cod, haddock, deepwater redfish and long rough dab. These species are major fish eaters with long migration routes. Meanwhile, the stocks are also large.

The living conditions for these fish species have improved in the northern Barents Sea, in terms of both temperature and food availability.

 

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2004: These were the areas where the fish communities could be found in 2004. Fish communities: Arctic (blue), Central (yellow) and Atlantic (red).

Copyright Havforskningsinstituttet

 

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2012: Eight years later, the translocation of the fish communities is drastic.

 

Problems in the north

It appears that the Arctic fish community does not cope with rising sea temperatures as well as other communities. This fish community includes species such as Greenland halibut, snailfishes, sculpins and eel pouts. Characteristic features of Arctic fish species are that they are small, stagnant and more dependent on finding their food on the seabed. As Arctic fish species have a more specialized diet, they are more vulnerable to climate change.

In addition, these species are adapted to life on the shallow shelf of the Barents Sea. Since the Arctic Ocean is much deeper, it is unlikely that these species will move further north than they currently are. However, we can find them further to the east.

More competitors

Large fish and marine mammals can move reasonably quickly over large distances, while other species, such as small Arctic fish species and organisms that live on or near the seabed, are more attached to one place. Two previously separate communities are now mixing together.

The big fish species from the south will compete with the Arctic species for food, and even feed directly on these smaller fish species. The Arctic community is being pressured from two sides; the marine environment is changing as a result of the rising temperature and new competitors and predators are arriving.

It is anticipated that this could result in the disappearance of some Arctic fish species, such as the gelatinous snailfish, from our northernmost areas.

Four times as fast

Many modelling studies have indicated that climate change, particularly increased sea temperatures, will result in species and communities moving, but few studies have shown that this would occur at the rate that we are now observing.

The IPCC estimated in 2014 that marine fish species moved by about 40 km per decade. We found that the fish communities in the Barents Sea moved up to four times faster than this in the period 2004-2012.

We are now working to map the impacts of this comprehensive relocation process. Meanwhile, we are benefitting from a large cod population that is extremely viable for commercial fisheries. However, it is uncertain whether this will continue over the next few decades.

It is hoped that ecologists studying the impacts of climate change will stay ahead of the changes that occur, thus making it increasingly possible to give notice of what will happen rather than reporting what has already happened. This is a challenge given the pace of the climate changes that we are currently experiencing.

Barents Sea Facts

Russian name: Barentsevo More
Size: 1.4 million km2 in surface area (approximately four times as large as Norway).
Depth: Average depth = 230 m, Maximum depth = 500 m
Fisheries: Bottom fish such as cod, haddock, Greenland halibut, long rough dab, and redfish. Other commercially important species include: capelin; northern shrimp; minke whales, and harp seals
Special features:

  • Large annual variations in temperature relative to ice coverage
  • A shallow sea which makes up a portion of the continental shelf around the Arctic Ocean
  • Has one of the largest concentrations of sea birds in the world: approximately 20 million individuals distributed across 40 different species
  • Management of living marine resources in the Barents Sea is carried out through collaboration between Norway and Russia.
The Barent Sea Ecosystem

Contact

Maria Fossheim
55 23 85 00