Aquaculture for all

Method Distinguishes Wild and Farmed Salmon

Salmonids Sustainability +2 more

UK - A new technology examining the chemistry of fish scales has been developed to tell the difference between farmed and wild salmon.

University of Southampton geochemist Clive Trueman, who led the research together with the Scottish Association for Marine Science, said fish scales are formed from the same chemicals as bones and teeth, preserving a chemical record of the water the fish lived in throughout its life.

The scientist found levels of the trace metal manganese were always much higher in farmed fish, according to a report on Official Wire.

The researchers say that the trace metal in the scales is probably cased by the manganese supplement in the fish food and because under the fish cages the conditions promote the recycling of manganese in the water column.

The team has been able to distinguish between farmed and wild fish with a 98 per cent accuracy.

The technology can be used to assess the proportion of escaped salmon in rivers as part of a potential wildlife conservation exercise.

The team also found differences in the chemistry of scales between fish farms that might allow researchers to identify individual farms responsible for the release of wild fish.

The research appeared in the journal Marine Ecology Progress.

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