Plenty more fish in the sea?

Summary

Podcast Summary: "Plenty more fish in the sea?"

Podcast: More or Less (BBC Radio 4)
Host: Yan Wong
Date: October 1, 2012

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Brief Overview

This episode of "More or Less" investigates widely circulated newspaper headlines about North Sea cod populations—most notably, claims that only "100 cod are left in the North Sea." The team unpacks the origins and accuracy of these statistics, highlighting how data misunderstandings can drive alarmist media narratives. The episode then shifts to the topic of data analysis in football, focusing on Manchester City’s decision to release match data for public analysis, and includes insights from influential baseball statistician Bill James.

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Key Discussion Points & Insights

1. The "100 Cod Left" Headline: Origin and (In)accuracy

• [00:13] Host Yan Wong introduces the "fishy statistic" from the Daily Telegraph: "Only 100 cod left in the North Sea," a claim that caused outrage among experienced trawlermen.
• [00:39] Trawlerman Brian Buchan (voiced by Bill James in this episode) expresses anger:

  “It made me so angry. In 34 years in North Sea fishing, we've seen more cod this year than we've seen the last 30 years. Then we get a headline from someone who probably doesn't even know what a cod looks like... More like 100 million cod in the North Sea.” [00:39]

• [01:08] Reporter Hannah Barnes investigates the headline’s validity with expert input.

2. How the Statistic Got So Distorted

• [01:16] Dr. Tom Webb, marine ecologist, confirms the figure is "clearly wrong." Many nets catch more than 100 cod in a single haul.
• [01:26] The story traces back to the Sunday Times, which claimed “100 adult cod in the North Sea”—still vastly misleading.
• [01:38] The error stems from misclassifying "adult" cod as those over age 13, when, in reality, cod mature much earlier.
• [02:17] Dr. Carl O’Brien (CFAS) clarifies:

  "Cod start to mature at ages one and two and they're fully mature by age six. The bulk of the mature cod in the North Sea at the moment is constituted of fish which are actually younger than seven years of age." [02:25]

3. Longevity Myths and Data Sources

• Journalists cited a maximum age of 25 for cod, drawn from Fishbase, but:
  • [03:12] Dr. Webb explains:

    "...the estimate of 25 was not from a North Sea cod, it was from a cod in the Barents Sea. And the only estimate for a North Sea cod of maximum age is 11." [03:12]

• The Sunday Times's assumption that cod over age 13 are regular adults, and that there are only 100 such fish, is therefore completely misleading.

4. The Real Numbers: Adult Cod in the North Sea

• [03:38] Using the same data set as the Sunday Times, the actual estimate is:
  • 21 million mature cod in the North Sea (cod of reproductive age), not 100.
  • [04:10] For the broader population, the figure is over 436 million cod.
• [04:17] Yan Wong jokes:

  “This could be a More or Less record, the most wrong number we have ever reported.”

5. Challenges in Fish Stock Measurement

• [04:35] Dr. Carl O’Brien explains the approach to estimating fish populations:
  • Combines sampling from port landings, data from fishermen, and scientific surveys at sea.
  • Emphasizes sampling, not exhaustive counting—methods are robust but unavoidably inexact.

6. Trends in North Sea Cod – Some Good News

• [05:17] Dr. O'Brien reports a gradual improvement in North Sea cod stocks since their historic low in 2006, and encouraging signs they are now recovering.

7. Media Response

• [05:42] Hannah Barnes relays the Sunday Times’s response, acknowledging they oversimplified and regret the confusion, noting they thought they were clear about referring to cod over 13 years.

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Memorable Quotes & Moments

• On media exaggeration:

  “Only 100 cod left in North Sea… more like 100 million cod in the North Sea.”
  —Brian Buchan (trawlerman), [00:39]

• On scientific sampling:

  "We do not try to count every single fish in the sea... we aim to sample a minimum of roughly 200 fish per thousand tonnes landed."
  —Dr. Carl O’Brien, [04:35]

• On cod longevity:

  “The estimate of 25 was not from a North Sea cod... the only estimate for a North Sea cod of maximum age is 11.”
  —Dr. Tom Webb, [03:12]

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Football and Statistical Analysis

1. Manchester City Opens Up Match Data

• [06:19] Gavin Flegg, Manchester City’s head of performance analysis, discusses the club’s decision to make its match data public:

  "We're now giving that opportunity to a wider community... a lot of the great work done in baseball and NBA in America has been done from people who didn't necessarily work at these franchises to start with." [06:19]

2. Bill James on Data Access and Its Impact

• [06:52] Baseball statistician Bill James recounts the struggle to obtain data:

  "We had a tremendous fight to get our hands on the numbers... so we said, ok, if the leagues won't share the information with us, we'll build a private fan-based scoring network..." [07:16]

• He addresses whether football is too chaotic for statistical analysis, noting the unique "opportunity" presented by less-structured sports.

  "...the problems involved with studying [football] are also opportunities. Those might be ways that you can find something that you couldn't find in baseball, because baseball is so static..." [07:50]

• On the benefits of data transparency:

  "If you're committed to staying on the leading edge of the research... that research will advance much, much faster with 1,000 or 100,000 fans looking at the data than with a handful of professionals looking at the data."
  [08:21]

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Timestamps & Key Segments

• 00:13 – 05:56: Debunking the "100 cod" statistic and explaining real fish stock science
• 05:56 – 08:55: Football, public data release, and statistical discovery (with Bill James and Gavin Flegg)

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Tone and Language

• Informative yet light, occasionally playful (e.g., references to “red herrings” and presenting Hannah as the “BBC’s cod correspondent”)
• Skeptical of statistical misuse
• Emphasis on clarity and fact-checking

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Takeaway

This episode is a prime example of "More or Less" holding media and public discourse to account through statistical rigor. It dismantles sensational headlines with expert evidence, demonstrates the importance of methodology in fisheries science, and celebrates the democratizing potential of data—whether in environmental science or football analysis.

Notable Quote for the Episode:

“This could be a More or Less record—the most wrong number we have ever reported.”
—Yan Wong, [04:17]

Transcript

[BBC Announcer]

Thank you for downloading from the BBC.

[Hannah Barnes]

For details of our complete range of podcasts and our terms of use, go to bbcworldservice.com podcasts

[Yan Wong]

hello, and welcome to More or Less on the BBC World Service, a haven of statistical straight talking in a world of nonsense. Today, we're starting with a particularly fishy statistic. The Daily Telegraph, a British newspaper, recently carried this headline, Only 100 cod left in North Sea. A dim future for cod, you might think. Well, here's what Brian Buchan thought. He's a trawlerman who's been fishing in the North Sea for decades.

[Bill James]

It made me so angry. In 34 years in North Sea fishing, we've seen more cod this year than we've seen the last 30 years. Then we get a headline from someone who probably doesn't even know what a cod looks like. This makes my blood boil. 100 cod in the North Sea. More like 100 million cod in the North Sea.

[Yan Wong]

It's not a trivial issue. Overexploitation and conflicts over fisheries cause major problems worldwide. So our reporter Hannah Barnes went trawling for the truth.

[Hannah Barnes]

Well, let's start with the headline 100 Cod Left in the North Sea from the Daily Telegraph. Could it possibly be true?

[BBC Announcer]

I don't think so. I think people are going out and catching more than 100 cod in a single net and at any one time in the North Sea. So it was clearly wrong.

[Hannah Barnes]

That's Dr. Tom Webb, a leading marine ecologist. It turns out that the Telegraph took the story from another British paper, the Sunday Times, which claimed that there are 100 adult cod in the North Sea. A different claim, but still wildly wrong. Here's what happened. The Sunday Times got the story by looking at data from isis, the International Council for the Exploration of the Sea. And it then asked researchers from the British Government's Centre for Environment, Fisheries and Aquaculture Science, or cfas, for help with the numbers. But to quote Cephas, the journalists misunderstood the data. For some reason, they decided to class an adult cod as over 13. But that's not merely an adult cod, it's an ancient cod. Now, we shouldn't be surprised that there are very few cod over 13.

[Bill James]

Just.

[Hannah Barnes]

Just as we aren't surprised, there are hardly any humans older than 100. Here's Dr. Carl O' Brien from CFAS.

[Dr. Carl O'Brien]

COD start to mature at ages one and two and they're fully mature by age six. The bulk of the mature cod in the North Sea at the moment is constituted of fish which are actually younger than seven. Years of age.

[Hannah Barnes]

So where did the newspaper get the idea that cods reach adulthood at 13? Well, in the same article, the Sunday Times states that cod can live to 25, which implies a 13 year old COD is merely middle aged, looking forward to paying off its mortgage and getting its kids off to university. Dr. Tom Webb thinks the journalist got that 25 figure from a website called Fishbase. He says that although Fishbase is a pretty reliable source of fish related information, the idea that cod in the north sea live to 25 is, well, a bit of a red herring.

[BBC Announcer]

For each species, it has a front page with some headline statistics. For instance, maximum age, which for cod is given as 25. But when you delve into where those statistics come from, it's all very well referenced in Fish Base and you can actually find that the estimate of 25 was not from a North Sea cod, it was from a cod in the Barents Sea. And the only estimate for a North Sea cod of maximum age is 11.

[Hannah Barnes]

So here's a question. Given what we now know about when cod mature, just how many adult cod, as the Sunday Times would put it, are there in the North Sea? Remember, they said there are just a hundred. The right answer. Well, using the same data set the Sunday Times used, it's actually 21 million. And as for the Daily Telegraph's version,

[Yan Wong]

only 100 COD left in North Sea.

[Hannah Barnes]

Well, here's a more accurate version of that headline, based again on the Same

[Yan Wong]

data, only 436,900,000 COD left in North Sea.

[Hannah Barnes]

This could be a more or less record, the most wrong number we have ever reported. But all this raises a more general question. How difficult is it to measure fish stocks across the world? And how reliable is the Official data? Here's Dr. Carl O' Brien again from CFAS.

[Dr. Carl O'Brien]

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. These data are used to estimate the size of commercial fish populations, such as the North Sea cod stock. We obviously use sampling methods and as a rough estimate, we aim to sample a minimum of roughly 200 fish per thousand tonnes landed. Our methods are rigorous and robust, with small errors of uncertainty.

[Hannah Barnes]

There it is. It's not a precise science, but you can get a pretty good idea. I also asked Dr. O' Brien to give me the general picture of what's been happening to cod stocks in the North Sea.

[Dr. Carl O'Brien]

The latest international assessment shows there's been a gradual improvement in the status of the stock over the last few years and, and the amount of mature fish has actually increased from the historic low in 2006 and does show signs of further improvement. So although there's a long way to go, there are good indications that the stock is ready to recover.

[Hannah Barnes]

That means that the newspapers could have looked at the latest COD data and reported a good news story.

[Yan Wong]

Thanks, Hannah. Did you ask the Sunday Times to respond to all that?

[Hannah Barnes]

Well, I did and they told me the article did oversimplify a complicated issue which, which they now regret. They also said they made clear that they were referring to cod over the age of 13.

[Yan Wong]

Hannah Barnes, the BBC's cod correspondent. Now, if you love football and numbers, listen up. The British football club Manchester City has announced that it's starting to make its match data publicly available for free in the hope that amateur statisticians the world over will be able to spot useful things in the numbers. Here's Man City's head of performance analysis, Gavin Flegg.

[Gavin Flegg]

The number of people looking at data and looking to expand our kind of objective knowledge of football is quite small because it ultimately relies on the people who are working full time in the clubs and the people outside of the clubs who have previously had the resources to go and purchase large data sets. We're now giving that opportunity to a wider community and you know, and ultimately a lot of the great work done in baseball and in NBA in America has been done from people who didn't necessarily work at these franchises to start with. Bill James is the most famous of examples who set about creating and collecting his own data in baseball with a number of other people who are interested, interested in this area.

[Yan Wong]

Gavin isn't the only stato to be inspired by Bill James. He's well known in the United States where his analysis of baseball stats collected by fans made him hugely influential. In 2006, Time magazine actually named him one of the 100 most influential people in the world. Richard Knight gave Bill James a call and asked him whether when he started out he had a fight on his hands getting hold of the numbers.

[Bill James]

We had a tremendous fight to get our hands on the numbers. In the first 10 years. A lot of information was proprietary and our first efforts to get a hold of better data for 10 years we were constantly told, no, you can't get that. No, you can't get that. And we simply didn't accept it. We said, okay, if the leagues won't share the information with us, we'll build a private fan based scoring network and we'll collect better data. Than they have.

[Yan Wong]

Could it be the case that this sort of exercise turns out to be a bit less useful to football than it was to baseball because baseball is a more orderly game with more clear things to measure?

[Bill James]

It could be. On the other hand, I have talked to people who know much more than I do about British football, soccer. They don't necessarily agree with that. The problems in studying a sport that moves rapidly from state to state and has vague boundaries between them, the problems involved with studying that kind of sport are also opportunities. Those might be ways that you can find something that you couldn't find in baseball, because baseball is so static that it drives out a certain type of opportunity for analysis.

[Yan Wong]

So you're pretty sure this will prove to be a productive exercise for Man City?

[Bill James]

I'm quite certain it will be a productive thing. I'd be extremely surprised if it doesn't. There is a risk that it produces something that you'd rather not. But if you're committed to staying on the leading edge of the research and staying informed about what the research is discovering, there's no question that that research will advance much, much faster with 1,000 or 100,000 fans looking at the data than it will with a handful of professionals looking at the data. A handful of professionals looking at the data will see the things that they expect to see, but the 100,000 fans looking at the data will see all kinds of things that no one had really expected to see.

[Yan Wong]

Bill James that's all we've got time for this week. Don't Forget our website, BBC.co.uk more or less and our email address, more or lessbc.co.uk. we'd love to hear from you. We'll be back next week, but until then, goodbye. More or Less was presented by Yan Wong. The producer was Richard Knight and the editor, Richard Varden.

[Hannah Barnes]

There are dozens of different podcasts now

[BBC Announcer]

available from the BBC, including news, documentaries,

[Hannah Barnes]

science, business, arts and sport. For details of them all, go to bbcworldservice.com podcasts.