The seas and oceans, where life began, are gradually turning into arid wastelands of water as a result of reckless fishing and pollution. According to a recent study by the WWF, over the past 45 years the quantity of fish fauna in our oceans has halved.

The situation could, however, be even worse: according to a new study published this week in Nature Communications, official estimates significantly understate global data on the quantities of fish caught. Researchers at the University of British Columbia, in Canada, found that between 1950 and 2010 the actual catch figures were 50 per cent higher than those voluntarily reported by member countries to the Food and Agriculture Organization of the United Nations (FAO).

According to the researchers, this phenomenon concerns data on industrial-scale fishing; estimates of small-scale catches, such as subsistence fishing, are generally not reported to the FAO. As a result, the FAO's official statistics understate the true global impact of fishing and the actual volume of catches.

The study argues that the United Nations figures must be supplemented by approximately 32 million tonnes of unreported catch every year. "The FAO does not have a mandate to correct the data it is given," explained Daniel Pauly, the study's lead author. "Countries have a bad habit of reporting only what they see."

The result is a systematic underestimation of fishing activity, which can involve considerable margins — "up to 30 per cent in developed countries and from 200 to 300 per cent in small island states," Pauly stated. To understand the true extent of this underestimation, Pauly and Dirk Zeller of the University of British Columbia, in collaboration with the NGO The Pew Charitable Trusts and with the support of an international network of 400 scientists, estimated the catches of more than 200 countries between 1950 and 2010.

After analysing a wide range of direct and indirect sources, the researchers compared them with the data released by the FAO. According to official figures, from 1950 onwards the global volume of fish caught increased steadily worldwide, reaching 86 million tonnes in 1996, after which it levelled off, declining slightly by almost 0.40 million tonnes per year. In 2010, again according to the FAO, the quantity of marine animals caught fell to 77 million tonnes.

The data obtained by Pauly and his team tell a very different story, pointing to far higher figures: from 130 million tonnes in 1996 to almost 109 million tonnes in 2010. The new estimates highlight how severely catch data had been undervalued; according to Pauly and Zeller, their findings could contribute to the formulation of better and more carefully considered policies to regulate fishing around the world.