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Norway’s position in the Environmental Performance Index 2006

In the Environmental Performance Index released last week at the annual meeting of the World Economic Forum, Norway has fallen from second to eighteenth place. The ranking is partially based on a Productivity Overfishing Index, defined as a relationship between biomass production and fish catches in a given area. Research carried out by IMR shows that it is not correct to use this index in the same way in different ocean regions as the transfer efficiency between different levels in the food chain varies widely from one type of ecosystem to another.

The Productivity Overfishing Index is based on the production of biological material in the form of carbon. By far the most of the carbon produced in the ocean is phytoplankton (plant plankton). As we move up the food chain, the biomass diminishes by a factor of about ten at each level and there are major differences in transfer efficiency between different ecosystems. In the huge upwelling systems off Chile, Peru, California, and Northwest and Southwest Africa phytoplankton production levels are among the highest in the world, but the transfer efficiency is low. Much of the phytoplankton in these systems falls to the seabed and is not exploited by zooplankton or fish.

At the other end of the scale we find arctic-boreal spring bloom systems such as the Norwegian Sea and the Barents Sea, where there is a moderate annual production of phytoplankton, but the transfer efficiency, which leads to production of zooplankton and fish, is high. Our ecosystems are thus capable of supporting some of the largest fish stocks in the world, and therefore some of the world’s largest commercial fisheries, because the food web is “designed” for the very efficient production of fish.

What this means is that it is highly inappropriate to use the Productivity Overfishing Index in the same way for all the oceans of the world, and conclusions drawn on the basis of using it in this way will be wrong.

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