Climate change will lead to ecosystem clash

For thousands of years, ice and harsh conditions have served as a natural barrier between species from the Atlantic and the Pacific oceans in the northern hemisphere. New research, however, shows that large fish populations will soon be able to make the journey northward and defy the barrier between the Atlantic and the Pacific.

In the study, which has just been published in Nature Climate Change, scientists forecast the potential northward progression of 515 fish species following climate change, and report the rate of potential species interchange between the Atlantic and the Pacific via the Northwest Passage and the Northeast Passage.

The prediction of the model used in the study is supported by the fact that a number of fish species have already moved northwards, Peter Rask Møller of the University of Copenhagen says.

“We know of some species that have already crossed over — the Alaska Pollock, an extremely important fish in the northern Pacific. In recent years we have suddenly observed Alaska Pollock off the coast of Northern Norway. It was originally believed that the fish observed belonged to another species because we’re simply not accustomed to thinking of fish on this side of the Atlantic might come from the Pacific,” says Møller, according to Science Nordic.

The Greenland whale is another species observed in the passages between the two major oceans.

“We predict that the exchange of species will start accelerating in 2050,” says the study’s author Mary Wisz from the Danish research insitution DHI.

According to the researchers, almost 3 million years have passed since the environment of the Arctic facilitated extensive exchange of species between the northern Pacific and the Atlantic – and since then only limited exchanges of certain species have taken place between the two oceans.

The cold barrier between oceans has led to species developing in different directions in the two oceans.

“Life in the two oceans has developed in isolation from each other, for which reason species have developed which are very different from each other. The consequences could be huge if they suddenly start mixing,” explains Wisz.

The scientists believe commercial fishermen in the northern Atlantic and Pacific may be affected – positively as well as negatively – by a mixing of the species from the two oceans.

“The North Atlantic and North Pacific contribute some 40 per cent of all fish caught globally. This will offer the fishermen the opportunity to catch new species, but it will also present huge challenges,” says Wisz.