Sooke Salmon Enhancement Society members taking Coho broodstock for the Jack Brooks Hatchery. Salmon are hand netted and transported to the hatchery where the eggs and milt are extracted from the fish. (Contributed)

‘Street-proof fish’ have better chance of survival, says researcher

New methods eyed by Vancouver Island hatcheries

There’s something about a hatchery environment that causes the fish raised for release into the wild to be a little less intelligent and less able to survive the stresses of the natural world, according to Jessy Bokvist, a University of Calgary master’s student in ecology and evolutionary biology who’s studying hatchery-raised fish at the Nitinat River Hatchery on Vancouver Island.

It’s a finding that may have a long-term impact on how fish are raised in hatcheries, including those reared at the Jack Brooks Hatchery in Sooke.

RELATED: Sooke hatchery in a new home soon

“I’ve been in touch with Rob (Robert Brouwer, manager of the Nitinat River Hatchery) and we’re aware of what’s been going on there, but at present we’re not geared up for that sort of production in terms of cement raceways and such,” said Bill Pedneault, hatchery manager at the Sooke Salmon Enhancement Society facility.

“It’s not something we’ve installed, but if it was worked into the facilities it might be worth it.”

RELATED: 20 million fry released

Bokvist’s research has shown that the hatchery environment has led to the development of what she called “naive fish” who may not know how to feed properly or possess the rudimentary survival skills needed in the wild.

“We’re trying to equip all the fish we release with appropriate life skills to improve their chance of survival when they’re introduced into the wild,” Bokvist said.

“It’s sort of like street-proofing your kids. Fish are actually very good learners and it doesn’t take much to give them a better chance when they’re released.”

At the Nitinat River Hatchery, Brouwer said there are three aspects of street proofing fish.

“We provide them with environmental enrichment, which can be as simple as introducing a current to the tanks or putting some branches into the tank so the fish have a place to hide from bullies and develop a sense of territory. We provide them with sensory stimulus … a sort of life skills training that can involve giving them food from the bottom of the pond,” Brouwer said.

“We also do some simple things like fish net scaring where we slap a net onto the top of the water to create a stressful environment that mimics natural predation.”

Thirdly, the hatchery looks to the “soft release” of its fish, utilizing lower density side channels or a sea pen that gives the young fish a chance to learn how to survive before they enter the harsh reality of the real world.

“What we do is related to what we call neurological elasticity, getting them to use their brains more than they would in an impoverished environment in the traditional tanks. We want to stimulate them so they can learn to think down the road.”

It’s an approach that Pedneault is open to exploring at the Sooke facility.

“Oh sure, absolutely,” he said, adding he is watching what is happening elsewhere and is prepared to change practices if warranted.

“We’re about giving [the fish] the best start that we can.”

The Jack Brooks Hatchery has a licence to raise 500,000 springs and 150,000 coho fry every year. A free pen operation also raises upward of 80,000 chinook salmon annually.



mailto:tim.collins@sookenewsmirror.com

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