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Something’s Fishy About Global Fish Catch Reports

Improved data on fish catches throughout the world have led to a misconception that there are more fish in the ocean, when in fact global marine catches have been declining by around 1.2 million tonnes per year since 1996, according to a study published in Marine Policy.

“A lot of the data was previously not captured, so when the reporting was improved it was not applied retrospectively,” said lead author Prof Dirk Zeller of the University of Western Australia. “This means that the emphasis is on the ‘present’ at the expense of the ‘past’ and does not paint an accurate picture of trends over time,” Zeller said.

“One example is Mozambique, where we found officials reported that small-scale catches ‘grew’ by 800% from 2003 to 2004. But what really happened was that the small-scale sector was massively under-represented in the reported data for the longest time, and when an improved reporting scheme was put in place in the early 2000s, improved catch data was added. A similar amount of fish was caught in previous years, but it was not in the reported data.

“This means that when Mozambique submitted its data to the Food and Agriculture Organisation of the United Nations (FAO), they were already biased, as neither the country’s statistical agency nor FAO insisted on undertaking retroactive adjustments. Many other countries’ statistics have the same issue.”

Zeller said efforts to improve the collection of fisheries statistics was highly commendable but needed retrospective data to paint an accurate picture.