The Norwegian bluefin tuna collapse: a lesson from history

Posted on September, 19 2007

Bluefin tuna used to swim abundantly in Norwegian waters. But rampant overfishing in the Mediterranean led to the stock collapsing there.

In the first half of the 20th century, large schools of East Atlantic and Mediterranean bluefin tuna would travel to the coasts of northern Europe each year as part of their annual migration.

Between June and October bluefin would fill the coastal waters of Norway. Here, they were relatively undisturbed by the fishing activity which targeted other species - but which benefited from tuna chasing garfish into the nets.

The introduction of hydraulic net lifts, harpoon rifles and other gear in the 1920s opened up the bluefin tuna to exploitation, however, and the species became a target itself with dramatically increasing numbers being caught from that period onwards.

Between 1949 and 1950 the number of specialist bluefin tuna fishing boats in Norway increased from 43 to 200, with Norwegian catches eventually exceeding 10,000 tonnes per year.

By the end of the 1960s, bluefin tuna had almost completely disappeared from the waters around Norway. By 1985, the stock had collapsed and the fishery was closed.

Population in crisis
Although the advent of new gear leading to the development of industrial fishing activity for the species was a factor in the decline, overfishing of the wider population is thought to be the decisive factor.

An abundant bluefin tuna population will have a wide geographical spread. As that population declines, one of its survival strategies is to reduce its geographical dispersal.

The bluefin which used to find their way to Norway were part of the same population which spawn in the Mediterranean, with high numbers crossing to Norway for feeding purposes.

It is believed that the declining health of the Mediterranean stock had a crucial ‘knock-on’ impact on the collapse of the Norwegian fishery, and although tuna fishing in Norwegian waters has all but stopped, the bluefin have not returned and scientists believe this is because the overall population is in crisis.

The Norwegian government hopes that the historical abundance of bluefin in their waters may one day return if the overall, wider population can be protected.

That possibility is closely linked to the plight of that wider population still found in the Mediterranean.

Conservation quotas
As a consequence, Norway is currently working within ICCAT (International Commission for the Conservation of Atlantic Tunas) to obtain overall fishing quota reductions, as well as stronger measures against IUU (Illegal, Unreported and Unregulated) fishing in the Mediterranean.

Moreover, in a move to take positive action to protect the stock, Norway requested from ICCAT a bluefin tuna quota to be allocated to conservation. As a consequence, Norway has a 53 tonnes “non-fishing quota” assigned exclusively to conservation. Norway also took the bold measure of banning bluefin tuna fishing by its own fleets in an attempt to conserve the seriously imperiled stock.

In spite of this action by Norway and the efforts of other ICCAT contracting parties, there is still no real recovery plan in place for the Mediterranean stock – regardless of dire warnings from ICCAT’s scientists that such a plan is urgently required.

As things stand, the remaining bluefin tuna look set to suffer the same fate as the once abundant stock of the North - total collapse.

There have been well documented examples of fish stock collapse over the last 20 years, but the picture for recovery is far less clear or understood. Read more on how scientists, including WWF marine experts, are increasingly studying these affected fish populations - and what they indicate about potential recovery.

Further information:
Gemma Parkes, Communications Officer
Tel: +39 06 8449 7224
Fishing for bluefin tuna in Norway, 1971