Overfishing means your menu might betray you

When a fish is gutted, skinned, boned and battered, how can a consumer tell what he or she is eating? With the world's fisheries in serious trouble due to overfishing, some fishes are being sold in the guise of others. 

Peter B. Marko of the University of North Carolina and colleagues write in this week's issue of the research journal Nature that some three-quarters of the fish sold in the United States as 'red snapper' come from a range of different species. 

This staggering statistic, the authors say, comes from detailed examination of the DNA of fishes, something not available to the piscivore in the street.  The genuine article, Lutjanus campechanus, constitutes the most important fishery in the Gulf of Mexico, but in 1996 the authorities in Mexico and the United States declared that it was being over-fished, and called for restrictions to be put in place. 

The demand for red snapper continued, however, perhaps fuelled by the misapprehension that it is more common than it really is. In such conditions, the researchers claim, an incentive is created for less valuable fish species to be passed off as more valuable ones. This also hoodwinks fisheries managers into crucially overestimating stock sizes of the real red snapper.