Skip to content

Nature

Salmon farming puts wild populations at risk

by Louise Murray 22 Aug 2011
Salmon farming puts wild populations at risk

Researchers have linked declining wild salmon populations with infestations of parasitic sea lice emanating from intensive salmon aquaculture in the Broughton Archipelago in Canada.

After a number of contradictory reports, scientists have correlated sea lice outbreaks with the depletion of wild salmon populations of pink and coho salmon.

The Broughton area is home to almost 100 discreet wild spawning areas in 64 rivers, large enough for there to be control areas for the scientists to include which have no salmon farms at all.

Young salmon making their way out to sea for the first time are particularly vulnerable. Free-swimming larvae of the parasitic sea lice infect juvenile fish, feeding on the surface tissues.

Severe infestation can lead to death. Mortality rates in pink salmon when sea lice are abundant is estimated at 88%, and only 1% when the lice were rare. They can also affect adult fish, and adult coho predating on infected juvenile pink salmon can become infected themselves.

Lead author Martin Krkosek, an ecologist at the University of Otago in New Zealand said, "More and more we are learning that intensive aquaculture causes environmental problems for wild salmon populations. Protected areas are needed to conserve remaining wild stocks."

The lice can be controlled by the use of parasiticides, but these are environmentally undesirable and continued usage in other countries has led to resistance arising in the sea lice in only 10 - 15 years. British Columbia salmon farmers have been using these chemicals since 2000, so time may be running out for this as a control mechanism for the lice. Norway is using biological controls in the form of wrasses, fish which will selectively feed on the parasites, but this is not yet widespread.

"Perhaps the only way to keep wild populations of salmon safe is to move aquaculture to a fully controlled and contained system onshore, rather than growing the fish in open pens in the sea, but this would be a far more expensive means of production and it remains to be seen whether the public will pay a premium for a greener fish," said Krkosek, adding, "Wild salmon migratory routes could be protected within Marine Protected Areas where intensive aquaculture is restricted or prohibited."

The paper was published in the Proceedings of the National Academy of Sciences (PNAS) today.

Top Image Credit: Spawning Salmon © Sarahtheo


Trending Eco-Friendly Clothing

Prev Post
Next Post

Eco-Friendly Shop

Women's Clothing

Eco-Friendly Clothing for Women Our online shop offers a wide range of sustainable women’s clothing products, including t-shirts, hoodies, vests, sweaters, shorts, and...
Shop Now

Men's Clothing

Eco-Friendly Clothing for Men Our online shop offers a wide range of sustainable men’s clothing products, including t-shirts, hoodies, vests, sweaters, shorts, and...
Shop Now

Kids Clothing

Eco-Friendly Clothes for Kids Our online shop offers a wide range of sustainable kids clothing products, including t-shirts, hoodies and jumpers. Our garments...
Shop Now
Someone recently bought a
[time] ago, from [location]

Thanks for subscribing!

This email has been registered!

Shop the look

Choose Options

Earth Times
Sign up for exclusive updates, new arrivals & insider only discounts

Recently Viewed

Sorry, there are no products.
Edit Option
Back In Stock Notification
this is just a warning
Login
Shopping Cart
0 items

Before you leave...

Take 20% off your first order

20% off

Enter the code below at checkout to get 20% off your first order

CODESALE20

Continue Shopping