Climate change threatens Arctic cod
Higher sea water temperatures have led to northwards migration of marine species that can create problems for the Arctic cod and other fish stocks in the Barents Sea, scientists believe.
In course of the last 13 years, about 300 southern species have been found in the western part of the Barents Sea or outside Svalbard, a new report from the Norwegian Directorate for Nature Management reads.
In the report scientist Torleiv Brattegard shows that more than 100 new species from more temperate waters have been established in Norwegian waters from 1997 until today. At least two thirds of these have entered our seas from Scotland and Shetland, and the rest have arrived from the coasts of Sweden and Denmark.
Brattegard says to NRK that higher temperatures are the only possible cause for the establishment of southern species in the Barents Sea:
- The fact that they are moving northwards is connected with a rise in the sea water temperature. There is no other explanation that we know of, he says.
Of the about 1600 benthic marine species that were defined as southern species in Norway in 1997, having their northern distribution limit somewhere on the Norwegian coast, 565 species have moved further north along the coast, on average 750-1000 kilometers during the period from 1997 - 2010
- It is frightening that the little rise in temperature that has been going on in the last years can make such a big difference, says senior adviser Ingrid Bysveen at the Norwegian Directorate for Nature Management. - When new species enter the food chain, it changes the conditions for competition for all the fish and animals already in the area, she adds.
- We don’t know the consequences of this yet, but we believe that it will become tougher for the cod and other fish stocks, Bysveen says. The higher sea water temperature itself can also mean that the habitats and spawning grounds for fish will move further north.