The United States, Canada, Russia, Norway and Denmark agreed to ban unregulated fishing in the rapidly melting international waters around the North Pole.

"We share the view that it is desirable to implement appropriate interim measures to deter unregulated fishing in the future in the high seas portion of the central Arctic Ocean," their declaration said.

The five coastal states, which signed the accord on Thursday, will prohibit fishermen from their countries to fish commercially in a 2.8-million-square-kilometer (1.1-million-square-mile) area - about the size of the Mediterranean Sea.

Thinking of the future

There is currently little concern that anyone would fish in the region as it is used to be covered by ice year round and there are no commercial fish stocks. But climate change has already melted away much of the sea ice. Some 40 percent of the area was briefly open water when summer sea ice shrank to a record low in 2012.

"Climate change is affecting the migration pattern of fish stock," the Norwegian government said in a statement. In the future, this region might be of great interest to fishing fleets.

Alf Haakon Hoen, the research director at the Norwegian Institute for Marine Research, told journalists that Arctic cod, also known as polar cod, could thrive in the region.

Where fishing is still allowed and who can do it

The World Wide Fund for Nature (WWF) Germany called the agreement "a first and good step into the right direction."

"Our aim is that the region around the North Pole stays completely free from fishing," WWF spokeswoman Britta König told DW, adding that much more will need to be done to achieve that goal. "This declaration alone won't guarantee that no commercial fishing will ever take place in the Arctic Ocean."

First of all, the Central Arctic Ocean is surrounded by so-called "economic zones" belonging to the five countries that signed the agreement, and commercial fishing will still be allowed in these national waters.

Secondly, the declaration's signatories have no authority to stop other countries from fishing in international waters. "We would like all states in the Arctic Council, including those with observer status, to sign a fishing moratorium," König said.

The declaration also prohibits explicitly unregulated fishing. Regulated commercial fishing is allowed.

A small part of the Central Arctic Ocean is already regulated by the North East Atlantic Fisheries Commission, König said, adding that "this region is not included in the ban."

Just a way to find out what's worth fishing?

Fishing for scientific purposes also is not prohibited. In fact, the five coastal states called for more research into the Arctic marine resources.

"We desire to promote scientific research and to integrate scientific knowledge with traditional and local knowledge with the aim of improving the understanding of the living marine resources of the Arctic Ocean and the ecosystems in which they occur," the countries said in their declaration.

Greenpeace spokeswoman Sophie Allain told journalists "it's clear that most of these countries are motivated by resource extraction, not protection." They see the melting of the ice sheet as an opportunity to fish further north, she added.