Creative Solutions to Net Pens
What Are Net Pens?

Grieg Seafood British Columbia
Net pens are large cages suspended in bays along the coast or in large lakes. The pens can hold thousands of fish. They allow the fish to grow in a natural environment with the right water conditions.
Most fish farms in Canada use net pens. They are efficient, and produce fish at a low cost.
The Challenges
Net pens carry some risks, given that the only barrier between farmed fish and the environment is a net. These risks are greater on the East and West Coasts, where wild salmon populations are in decline.
- The pens can be damaged during storms, allowing fish to escape. Fish that escape compete with wild fish for habitat and food. On the East Coast, they can even breed with wild Atlantic salmon.
- The large number of fish in the pens attract sea lice, a common salmon parasite.
- There is a risk of exchanging diseases between farmed and wild fish.
- Fish poop and food accumulate under the net. This excess accumulation can cause pollution.
Creative Solutions
Fish farmers and researchers are coming up with creative ways to make net pens more sustainable. Here are a few examples.

vesselfinder.com
This vessel has a freshwater bath in its hold in which to immerse the salmon. The freshwater does not harm the fish, but it does cause the sea lice to fall off their hosts.

Neptune Marine
This barge uses water pressure to remove sea lice and their eggs from salmon.

AKVA group
In this special pen, a net keeps the salmon deep in the water, where there are fewer sea lice.

AKVA group
By distributing feed deep in the water, farmers can encourage the salmon to swim below the level where sea lice are found.
Rather than managing sea lice alone, West Coast salmon farmers are now required to share information with each other about lice levels on their farms. This allows them to coordinate their efforts to control the parasite.
Research is underway to design an enclosure that would collect and remove salmon poop and excess feed.

British Columbia Salmon Farmers Association
This sturdy net has a strong anchoring system that makes it more resistant to storms.

Natalia Sidorova/Shutterstock
These tiny lumpfish are hungry for sea lice. As they feast on the lice attached to salmon, they help control the parasite.

British Columbia Salmon Farmers Association
These floating closed pens will separate farmed fish from the surrounding environment.

British Columbia Salmon Farmers Association
Farmers use cameras and artificial intelligence to monitor fish and supply just the right amount of feed.