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Media cod claims: "the most wrong number ... ever reported"

03 October 2012

Recent media reports about the number of adult cod left in the North Sea came under scrutiny during the BBC World Service's More or Less programme recently.

The programme makers aimed to discover the truth behind headlines that claimed only 100 cod were left in the North Sea. What they found was in fact very different.

The BBC's Hannah Barnes indicated that the disparity between the media headlines and the true figure for cod in the North Sea was huge and that at least one media headline  "... could be a More or Less record, the most wrong number we have ever reported."

Cefas' Dr Carl O'Brien and others were interviewed for the programme. Dr O'Brien explained that cod start to mature at ages one and two and are fully mature by age six. He continued: "The bulk of the mature cod in the North Sea at the moment is constituted of fish which are actually younger than 7 years of age."

Unfortunately, despite having access to the latest ICES data, UK journalists misunderstood those figures and chose to class an adult cod as over 13.

Hannah Barnes said: "That's not really an adult cod, it's an ancient cod. Now we shouldn't be surprised that there are very few cod over 13, just as we aren't suprised that there are hardly any humans older than a hundred."

And what of the Sunday Times' claim that there are only 100 adult cod in the North Sea? Referring to the same dataset used by the paper, the actual figure is 21 million. The newspaper has since printed a correction and changed aspects of their original article online.

And as for the Daily Telegraph's claim that there are only 100 cod left in the North Sea?  A more accurate estimation, suggested the programme, is 436,900,000 cod left in the North Sea. It is this disparity that the More or Less programme claimed to be "the most wrong number we have ever reported".

The programme went on to discuss how difficult it is to measure fish stock numbers.

Dr O'Brien said: "As fisheries scientists we do not try to count every single fish in the sea, instead we collect information from three main sources: from landings at ports, from fishermen themselves, and from research vessels.

"...as a rough estimate we aim to sample a minimum of roughly 200 fish per 1,000 tonnes landed. Our methods are rigorous and robust with small errors of uncertanty."

He went on: "The latest international assessment shows there's been a gradual improvement in the status in the stock over the last few years. And the amount of mature fish is actually increased ... and does show signs of further improvement."

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Last Modified: 04 October 2012