Truth or Fic­tion?

Seals are re­ported to dev­as­tate sal­mon farm stocks, but what are the al­ter­na­tives to killing them and do they work? Bi­ol­o­gist David Ains­ley re­veals the truth.

BBC Wildlife Magazine - - Contents - DAVID AINS­LEY is a ma­rine bi­ol­o­gist, tour op­er­a­tor, diver and un­der­wa­ter cam­era­man.

Do seals need to be culled to pro­tect sal­mon stocks in Scot­tish wa­ters?

THE SHORT AN­SWER IS NO. It is cer­tainly true that seals can dam­age nets and kill sal­mon in Scot­tish wa­ters; sal­mon pro­duc­ers say they cause “mil­lions of pounds’ worth” of dam­age ev­ery year. But they also ac­cept that shoot­ing seals should only be an ac­tion of last re­sort and say they as­pire for it to be­come un­nec­es­sary. They have made progress to­wards this goal in re­cent years: they say 49 seals were legally shot in 2017, an 84 per cent re­duc­tion on the num­ber in 2011.

David Ains­ley, a ma­rine bi­ol­o­gist who op­er­ates a tour-guid­ing busi­ness on Scot­land’s west coast, says shoot­ing seals would be com­pletely un­nec­es­sary were sal­mon farm­ers to use dou­ble net­ting to con­tain their fish, as they do in Bri­tish Columbia.

Ains­ley be­lieves there is a big­ger is­sue at stake, how­ever. Many sal­mon farms – 121 out of 172 listed by Ma­rine Scot­land – rou­tinely use acous­tic de­ter­rent de­vices (ADDs), which send out blasts of noise to keep seals away from fish pens. He says this ei­ther dam­ages the hear­ing of seals and Euro­pean pro­tected species such as por­poises, dol­phins and whales, or forces them to aban­don whole ar­eas be­cause of the noise. “These ADDs can cause dis­tur­bance, stress and hear­ing in­juries,” Ains­ley says. “And for echo-lo­cat­ing mam­mals [such as por­poises], hear­ing in­juries are a death sen­tence.” One study found that the use of ADDs had ex­cluded por­poises from 87 per cent of a 990km2 area of sea.

Ains­ley has sub­mit­ted a com­plaint to the Euro­pean Com­mis­sion about the use of ADDs be­cause he says they con­tra­vene both Scot­tish and Euro­pean leg­is­la­tion. Scot­tish Nat­u­ral Her­itage states: “In Scot­tish in­shore wa­ters, it is an of­fence to in­ten­tion­ally or reck­lessly kill, in­jure, cap­ture, dis­turb or ha­rass a cetacean.”

The Scot­tish Sal­mon Pro­duc­ers Or­gan­i­sa­tion (SSPO) says its mem­bers ad­here to a code of prac­tice, which rec­om­mends the use of ‘seal blinds’ (to pre­vent seals from see­ing the fish at the bot­tom of the pens), heavy ten­sion­ing of the nets and ADDs. “The dam­age seals cause to sal­mon is se­vere and ex­ten­sive, killing many by tak­ing sin­gle bites out of each fish then leav­ing them to die,” said the SSPO in a state­ment.

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Shoot­ing seals would be com­pletely un­nec­es­sary were sal­mon farm­ers to use dou­ble net­ting.

Pro­duc­ers say the dam­age seals cause to sal­mon can be ex­ten­sive.

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