Labels that reveal the origin of fish in food products have been under the spotlight, following a recent study carried out in France.
The European research examined the issue of fish traceability and found that rates of labelling fraud are much higher in some countries than others.
According to the survey, the problem has been found to be as high as 32 per cent in Italy and 30 per cent in Spain, compared with lows of six per cent in the UK and 3.5 per cent in France.
Species fraud was discovered to be in evidence in France, with certain types of seafood being replaced by others - in particular bluefin tuna.
Carried out by a team of experts, the research covered ten regions of the country and almost 400 samples were looked at to identify whether or not there is a problem with fish labelling within France.
It was conducted in the wake of the European Union horsemeat scandal, in which products labelled as beef were found to contain equine tissue.
Organisations Bloom and Oceana teamed up with researchers from the National Museum of Natural History and the National Institute of Health and Medical Research, and Terra eco magazine, finding that species substitution in France is low.
Samples were taken from an array of sites - including supermarkets, frozen meals, restaurants and fish markets - with no fraud found among seabass, monkfish, whiting and Alaskan Pollock.
However, labelling was incorrect for six out of 143 samples of cod, with lesser value fish such as hake or haddock substituted, while 80 per cent of samples packaged as bluefin tuna were found to contain cheaper types of tuna.
Examining the seafood supply chain, the researchers found incidents of wrong labelling tended to occur at the end, with admissions from fishmongers and restaurant owners that they had previously mislabelled items.
Oceana, which promotes responsible fishing, claims that some studies have suggested that seafood mislabelling may occur in between 25 to 70 per cent of cases for certain species of fish in the US.