Global fisheries' catches have been substantially underestimated over the past 60 years, and are declining more steeply than current estimates suggest, finds a study in Nature Communications. These results are based on a process of so-called ‘catch reconstruction’, which aims to improve officially reported catch statistics by scouring the scientific literature and asking local experts whenever data is missing.
The Food and Agriculture Organisation of the United Nations (FAO) collates fisheries catch data submitted to it from member countries, which constitute the only global fisheries catch dataset of its kind available to scientists and policymakers. However, there is evidence that some member countries may omit data on small-scale, recreational, or illegal catches, as well as unwanted discards, potentially resulting in a misleading picture of the state of global fisheries.
Whenever instances of 'no data' are recorded on a national record, these values are usually scored as 'zero' in FAO records, which may not give an accurate reflection of catches.
Using data gathered by over 100 collaborators from more than 50 institutions, Daniel Pauly and Dirk Zeller update these statistics. Their estimates suggest that the total global fisheries catch recorded between 1950 and 2010 has been underestimated by more than 50% (total difference in catch data by weight). Although both FAO statistics and the updated estimates show steady increases in catches every year since recording began in 1950, the updated dataset indicates that global catches peaked at 130 million tonnes in 1996, before declining by around 1.2 million tonnes per year up to 2010. In contrast, FAO estimates record the peak in the same year (1996) to be 86 million tonnes, after which catches are believed to decline at a rate of only 0.38 million tonnes per year.
The authors propose that these differences are largely due to greater decline in catches from the industrial fishing sector (rather than from artisanal or recreational sectors), although they also acknowledge their analysis cannot separate out specific factors that may be causing this decline, and that both FAO estimates and these new estimates are subject to high levels of uncertainty.