Thousands of salmon worth about £240,000 have escaped from an Argyll fish farm, raising fears that they will breed with wild fish stocks and dilute the purity of the stock.

The 16,000 fish, weighing an average of 10lb each, escaped from the Marine Harvest farm at Carradale.

The fish escaped through a hole in the net following stormy seas and winds of up to 70mph in the early hours of June 2.

The company estimates that the escape has cost it in the region of £240,000.

It was the biggest escape from a Scottish mainland marine salmon farm since 2009 at Strone Point in Argyll when nearly 59,000 fish escaped from a farm operated by Lighthouse Caledonia.

The Salmon and Trout Association (Scotland) (S&TA) says that the fish are mature, therefore they will migrate into important salmon rivers in the Firth of Clyde, genetically diluting wild stocks.

Marine Harvest maintains that the fish were not mature, and therefore will not attempt to migrate into local rivers, but will swim out to sea. The company said it farms with specially selected slow maturing stocks.

It is thought that the 16,000 escaped fish may exceed the number of wild adult salmon running in the rivers flowing into the Firth of Clyde.

Guy Linley-Adams, solicitor to the S&TA, said: “There is a real danger that these fish may survive in sufficient numbers to breed with wild salmon in this area, leading to the genetic dilution of the wild fish population with farmed fish, which are largely descended from Norwegian and not Scottish fish. This is very bad news for the long term survival of western Scotland’s wild salmon.”

The pen had been stocked with 24,000 fish. The weather was particularly bad on the late afternoon and night of June 1. Nets had been checked that day.

Allan Sutherland, managing director of Marine Harvest (Scotland) Ltd, said: “The escape happened as the result of a tear in the net during the bad weather conditions. As the fish were immature they would have headed straight out to sea.

“When we became aware of the escape we immediately checked all the nets on the farm and notified the appropriate organisations. Marine Harvest has been working with the Scottish Government and partners in the industry to develop the Scottish Technical Standard for containment which aims to prevent fish escapes. Our aim as a company is to prevent fish escapes altogether and we very much regret this incident. We will continue to closely monitor all the equipment on our farms to ensure that fish escapes do not happen in the future.”