Adjusting the estimated of global fish catch

Tens of millions more tonnes of fish have been taken from the seas than are recorded in official statistics, suggests a huge and controversial project aiming to estimate the ‘true catch’ of the world’s fishing industry.

The work is detailed in a paper in Nature Communications by fisheries researchers Daniel Pauly and Dirk Zeller of the University of British Columbia in Vancouver, and it builds on a decade-long project that has drawn in hundreds of researchers from around the world.

According to Pauly and Zeller, global fisheries catches hit a peak of 130 million tonnes a year in 1996, and they have been declining strongly since then. This is substantially higher than the data collected by the Food and Agriculture Organization of the United Nations (FAO), which report that catches reached 86 million tonnes in 1996 and have fallen only slightly.

The FAO numbers have long been the only estimate of how many tonnes of fish are caught at a global level. But “the FAO doesn’t have a mandate to correct the data they get”, Pauly told journalists during a conference call.

This leaves the organization reliant mainly on the numbers submitted by member countries, he says, and “the countries have the bad habit to report only the data they see”. This means that many official statistics do not account for a huge amount of the world’s fisheries catch, such as that by small-scale and subsistence fisheries or fish thrown back as ‘discards’ — species other than those being hunted.

Nature Communications – Catch reconstructions reveal that global marine fisheries catches are higher than reported and declining

Trajectories of reported and reconstructed marine fisheries catches 1950–2010

The reconstructed 2010 catch was 15% below peak landings of 130 million mt in 1996, estimate the researchers, who are based at the University of British Columbia (UBC), Vancouver in Canada. In contrast, FAO figures for the same 14-year period showed an 11% decline, from 86 million mt to 77 million mt.

According to the study they claim the FAO statistics have understated the size of the global seafood catch by about 30%.

This does not include about 73 million tons of farmed fish (aquaculture) in 2014.

SOURCES- Nature, FAO, Nature Communications