Fish Forensics

A highly accurate genetic testing method could help pinpoint illegal and mislabelled fish, a team has reported in Nature Communications.

About 20 percent of fish caught around the world fall into the category of illegal, unreported or unregulated (IUU) fishing. Some agencies have demanded that the fish’s origin be stated on a catch certificate, and ‘eco-labels’ can indicate whether a fishery has been certified for sustainable practices. But better methods are still needed to verify that the information on catch certificates and labels is correct, the study authors argue.

DNA is an ideal tool, since it “can be analysed in any tissue type, from freshly caught fish to a fried fillet,” the team writes. The researchers proposed using a particular type of genetic signature called gene-associated markers. Since each population of fish will face different evolutionary pressures, those differences ought to be reflected in individual genes that are changing through natural selection.

The team tested the method on Atlantic cod, sole, Atlantic herring, and European hake. First, the researchers looked for genetic tweaks that appeared to be specific to certain populations. Then they ran analyses to determine how accurately fish could be identified based on these DNA markers.

The method could correctly pinpoint the population that a fish came from 93 to 100 percent of the time. Gene-associated markers could “become highly valuable tools for fighting illegal fishing and mislabelling worldwide,” the team concluded. Roberta Kwok | 23 May 2012

Source: Nielsen, E.E. et al. 2012. Gene-associated markers provide tools for tackling illegal fishing and false eco-certification. Nature Communications doi: 10.1038/ncomms1845.

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