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Fishing For An Answer: Wild Or Farmed?

by the Fish Site Editor
02 August 2007, at 1:00am

SCOTLAND - Scientists at the University of Stirling's Institute of Aquaculture have developed a method that may help to solve mislabeling problems for wild and farmed fish product - and may also boost consumer confidence.

A test has been developed by J. Gordon Bell and colleagues at Sterling that can detect differences in the composition of the fatty components found in farmed and wild species.

Tests done on 10 wild and 10 farmed sea bass, showed significant differenced on body composition. The Wild sea bass had a significantly lower flesh lipid content than farmed sea bass (P < 0.0001), and also had a higher choline nitrogen content than farmed bass (P = 0.0002).

In most fish species, flesh lipid content increases with weight and age of the fish (27). However, in this case, the wild fish were more than three times heavier than the farmed fish, yet the lipid was less than half the value in the wild fish compared to the farmed product. The differences originate because farmed fish usually get a diet containing lower levels of marine-derived ingredients. This would suggest that the dietary fat is having a greater influence on flesh fat levels than the size and age of the animal.

Same effect in other species
Sterling's research team now want to further their investigations with large scale trails to verify their findings. They also want to study other fish species, because other research has demonstrated similarly elevated flesh lipid levels in farmed versus wild fish including gilthead sea bream (Sparus aurata), red porgy (Pagrus pagrus), rainbow trout (Oncoryhchus mykiss) and Atlantic salmon (Salmo salar).

Team leader Bell says that European Union legislation requires that retailers and consumers have information on the geographical origin and production method for seafood. However, he says that to the global nature of production, similar fish products can be sourced from variable points of origin, and this can lead to instances of mislabeling, both intentional and fraudulent.

He says that other considerations, aside from price, make it important to distinguish between wild and farmed fish, the and this test may help to address labeling issues and bolster consumer and retailer confidence.

A full report of this study is published in the ACS Journal of Agricultural and Food Chemistry, (25 July). Click here to view the paper

the Fish Site Editor