Research carried out by The University of Western Australia and The University of British Columbia has found inaccuracies in the data collected globally on fish catches.
The researchers found that improved data collection on fish catches in recent years by countries throughout the world has 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.
The research was carried out by the Sea Around Us researchers (an research initiative at the UWA and the University of British Columbia).
Lead author, Professor Dirk Zeller from UWA’s School of Biological Sciences and the Sea Around Us – Indian Ocean said the recent improved reporting included unmonitored fishery, region and fleet data not previously collected.
“A lot of the data was previously not captured so when the reporting was improved, it was not applied retrospectively. 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,” Professor Zeller said.
“One example is Mozambique where we found officials reported that small-scale catches ‘grew’ by 800 per cent 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.”
Professor Zeller said countries’ efforts to improve the collection of fisheries statistics was highly commendable but needed retrospective data to paint an accurate picture.
The scientists suggest using methods such as the Sea Around Us reconstruction approach to fill gaps with best estimates of unreported catches.
The study has been published in Marine Policy
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