The findings, reported in the Cell Press journal Current Biology on 18 July, come as surprisingly good news amid widespread criticism that the European Union's Common Fisheries Policy is failing, the researchers say.
"Contrary to common perception, the status of our fish stocks is improving," said Paul Fernandes of the University of Aberdeen. "Many of our stocks are not overfished; nature now needs to take its course for these fish to rebuild their populations."
"We should be aware that low fishing pressure needs to be maintained until stocks recover," said Robin Cook of the University of Strathclyde. "This is only the first step. Now we need to see numbers increase as a result of continued low fishing pressure."
There is reason for continued caution as several stocks, cod in particular, remain in trouble. Under today's strongly enforced catch limits, too many fish that would have been sold on the black market continue to be caught and discarded.
The researchers relied on data collected largely by government research institutes, including large programs at hundreds of fish markets and at sea on hundreds of fishing and research vessels operating every day of the year. The data consist of millions of measurements of fish: their length, weight, sex, developmental stage, and estimated age. These data were then analyzed and integrated into mathematical stock assessment models and peer reviewed at the International Council for the Exploration of the Sea (ICES) in Denmark, which recommends catch levels to the European Commission.
Drs Fernandes and Cook say they were especially surprised by the sheer number of stocks that have improved since fishing pressure was reduced at the turn of the century. In 2011, for the first time, the majority of fish stocks were being fished sustainably, the result of reforms put in place in 2002.
The findings come at an important time, when changes to the Common Fisheries Policy are anticipated.
"Further reforms to the Common Fisheries Policy are currently being developed, so it is important, when correcting its weaknesses, to also acknowledge and build on the success of a major reduction in the fishing pressure on European fish stocks," the researchers wrote.
Bertie Armstrong, chief executive of the Scottish Fishermen’s Federation: “I am delighted by this report. It confirms in a rigorous scientific way what our fishermen have telling us for some time - that the NE Atlantic fish stocks are increasing in size and are being harvested sustainably, with fishing pressure now at its lowest level in decades.
“Much of this has been achieved by the innovation of our fishermen in adopting a range of measures to reduce discards and to protect juvenile and spawning fish. All serious scientific analyses and commentary on NE Atlantic fish stocks are now pointing in the same direction. This will I hope be a refreshing insight for the public, fed until now largely on a diet of stories of negativity and decline.
“It must not be forgotten the considerable sacrifices made by our fishermen in reaching this stage, with the fleet significantly smaller than a decade or so ago and many boats now struggling for survival. With fish stocks currently increasing and being fished at sustainable levels, it is now more important than ever that the correct management system is put in place to ensure that there is a viable fishing fleet in place to harvest this wonderful resource.”