The mounting evidence suggests that climate change is making the earth warmer, with fish typically found in warmer waters appearing in the North Sea and local species moving to cooler seas.

Harald Asmus, marine biologist from the Bremen-based campus of the Alfred Wegener Institute (AWI) said in an interview with German press-agency DPA that they have found species of fish that are usually found in the warmer waters of the Biscaya and the Mediterranean are now being "frequently found" in the North Sea.

Species changing waters

Research conducted by Asmus for the Institute found that there has been a continual and definite decline in the number of local species.

"Unless the warming of the North Sea stops, this process (of changing fish stocks) will continue," Asmus said.

According to Asmus, one of the more obvious indications that climate change is having an effect is the slowly climbing average temperature of the North Sea-waters.

"For the last 18 years, the water has been getting continuously warmer -- that is the longest warm period since the records began 130 years ago."

Small climate change has big impacts

Although the increase is only around one-tenth so far, which equals a temperature change of less than two degrees, species have already started reacted to the variation.

"Certain fish types, like the plaice fish, plunge into deeper and colder waters, while other types like cod are drawn still further north", Asmus said

In return more and more fishes move from the southern and warmer waters into the North Sea.

"We have even already discovered anchovies here," he added.

Exotic creatures, like the pacific oyster are now being found, with the increased temperatures but mussels which once dominated the North Sea, have now been displaced.

Asmus is of the opinion that the changes will be be more rapid in the future and that the extinction of species in the medium-term cannot be discounted.

"These species have no chance to adapt to these new living conditions but rather they can only avoid it," Asmus said. "At present, we do not know what will happen with the Arctic region if the warming of the sea water further continues."

The temperature variations of the North Sea however, is not just a phenomenon restricted to the Atlantic, Asmus explained.

"Through global warming, more and more subtropical species are moving into the Mediterranean Sea,(and) we have also observed similar changes off the coasts of West Africa."