Scientists fear for cod stocks as study reveals there are just 100 adult fish in the North Sea
Cod can live for 25 years and become more fertile with ageScientists want quotas slashed so fish numbers can be restored

There are fewer than 100 adult cod in the North Sea because of decades of overfishing, it was revealed today.

The dwindling numbers raise fears for future stocks because cod, which can live as long as 25 years and grow to 6ft, become more fertile as they age.

Fishermen did not catch a single cod over the age of 13 last year, according to a study of sea ports across Europe.

Under threat: Cod numbers are dwindling in the North Sea because of overfishing

Under threat: Cod numbers are dwindling in the North Sea because of overfishing

The lower life expectancy meant a lower birth rate and a faster decline, warn scientists. Now they want North Sea quotas to be slashed so numbers can be restored.

Callum Roberts, professor of marine biology at York University, blamed industrial fishing for few cod living beyond four years old – the age when they reach sexual maturity.

He told the Sunday Times: “This means that there are fewer eggs and larvae to perpetuate future generations.”

An analysis carried out by Defra’s fisheries laboratory, the Centre for Environment, Fisheries and Aquaculture Science (Cefas) of around 500,000 fish in England and Wales found 191 million one-year-old cod and just 18 million three-year-olds.

Study: Analysis showed not a single cod over the age of 13 was caught at North Sea ports across Europe in 2011

Study: Analysis showed not a single cod over the age of 13 was caught at North Sea ports across Europe in 2011

In the North Sea, there were 65,300 tons of cod aged three or more while in 1971, an unusually high year for cod population, there were 276,000 tons.

The decline in cod has also meant a boost in populations of their prey such as scampi.

Chris Darby, head of the Cefas team, told the paper: “Our latest assessments suggest in 2011 there were 600 cod aged 12 to 13 in the North Sea, of which about 200 were caught.

“None of the catches recorded at North Sea ports around Europe showed any fish aged 13 or over. Analysis of that data suggests there are fewer than 100 such fish in the whole North Sea.”

Scientists want this year”s quota of 32,000 tons reduced in 2013 to 25,600 tons. In the 1970s 360,000 tons were hauled in by fishermen.

Barrie Deas, chief executive of the National Federation of Fishermen’s Organisations, said: “The most effective measure in rebuilding fish stocks seems to be removing vessels from service by paying owners to decommission them.”