THE Friends of Tavistock Wharf were offered a background to 'Salmon Farming and History' on Monday, March 2 by chairwoman of the group, Dr Ann Pulsford.

Using her interest and expert marine knowledge, Dr Pulsford spoke for an hour challenging perceptions of salmon farming.

Salmon fishing was once so common in the River Tamar and River Tavy that the Tamar later became an 'index' river to monitor Atlantic salmon populations.

However, these populations experienced a decline in the 19th century due to mining pollution. As a result, the local community saw fisheries close and could no longer enjoy the spectacle of mature salmon migrating to spawning grounds upstream, leaping up Tavistock Weir on their way.

Fortunately, stocks have begun to recover with five net fisheries re-opening on the River Tamar and one on the Tavy with a quota system in 2014. Yet only 0.5% of salmon eaten today is from wild stocks. The majority comes from salmon farms, predominately in Norway, Scotland and Canada, in an effort to meet demand as it has moved from a luxury food to a dietary staple.

Dr Pulsford presented some stark facts and figures during her talk, which explored the intricacies and knock-on effects of ecosystem interactions and difficulties of farming a migratory species in a body of water.

Predators, disease, physiology, modern techniques and solutions were methodically explained to question the long-term sustainability of such practices.

Perhaps the most startling fact of the talk was that 3lbs of wild caught anchovy is required to harvest just 1lb of salmon.

Dr Pulsford succeeded in encouraging thought as to the origin of foods at the supermarket.