Hatcheries, dams may help salmon survive floods, droughts

Written By Tom Davis

In a little over a year, British Columbians suffered a harsh sampling of what climate change might deliver – 2021 was the third worst wildfire year in history.

On June 30th, during a scorching heat dome, British Columbians were stunned as the historic community of Lytton burned to the ground.

Last November, southwestern B.C. was hammered with severe flooding, earning the title of “worst weather storm in a century” according to Transportation and Infrastructure Minister Rob Fleming. Whatever descriptive was used it was a heck of a rainstorm. British Columbians also learned what an ‘atmospheric river’ was, and they didn’t like it. 

This summer delivered a prolonged drought which lasted until the end of October. Rivers ran dry and normally green parks and lawns turned desert brown, forcing water restrictions in many areas.

Change is coming

These events not only affect people. Individually, each puts pressure on Pacific salmon. Collectively, these events sent a blunt message that change is coming, and time is running out for implementing solutions. 

The real fire damage is indirect, cumulative and long term.

Wildfire impacts on salmon are seldom recognized. They cause rapid death if water temperatures rise too high, however the real damage is indirect, cumulative and long term. Fires destroy vast tracks of forest-cover and ground vegetation; both of which play an important role in protecting the forest’s “sponge” capacity.

The problem is magnified in burnt-over watersheds with steep terrain. Here, even normal rains carry soil and other debris into valuable watercourses. Over time sediments clog spawning gravel and reduce salmon egg-to-fry survival rates.

Floods destructive to migrating salmon

The 2021 floods were tragic for people and destructive to migrating salmon. Massive amounts of rainwater overtopped stream banks and dikes turning farmers’ fields and parking lots into lakes and backwaters.

Flooding in Abbotsford, November 2021. [Photo Fraser Valley Fishing Guides

While providing temporary refuges for salmon, they turned into death traps when the water receded.

The Fraser Valley was one of many hard-hit regions. Fortunately, a small army of anglers and fishing guides came to the rescue.

Organized as the Fraser Valley Fishing Guides Association Recovery Effort, they volunteered to bring residents, pets and farm animals to safety. On return trips, they transported medical supplies and basic necessities to those who were trapped but not in danger. When flood waters began to recede, many volunteers pivoted to rescuing salmon and sturgeon.

Releasing stranded sturgeon on the Fraser River in November 2021.
[Photo Fraser Valley Fishing Guides Association]

High velocity floods create another threat to salmon and repetitive flooding incrementally reduces the chances for salmon recovery.  

“If fall and winter floods occur, river flows scour out deposited eggs and sweep them away, or cover them under gravels that are transported downstream causing them to die from lack of oxygen,” explained retired Department of Fisheries and Oceans biologist Brian Tutty.

Droughts damage spawning

In 2022, B.C.’s interior and coastal regions suffered through a third looming climate threat when drought conditions dominated the weather picture from early July to the end of October. 

Rob Brouwer has managed the Nitinat River Hatchery for decades. Brouwer said he’d never seen the river go subsurface before. 

“While the hatchery reached its Chinook egg target, approximately 5,000 Chinook were stuck at the river mouth, while another 10,000 were forced to spawn where they had never spawned before,” Brouwer said.

“If the females remain in salt water too long, the water seeps into their eggs rendering them useless.”

Brian Tutty

Fall droughts can play havoc with a whole generation of salmon., said Tutty. “A fish out of water is an old adage and a deadly one. Not only are they susceptible to excessive predation while staging in the estuaries, if the females remain in salt water too long, the water seeps into their eggs rendering them useless.”

Large sums of money have flowed to the “salmon recovery industry,” wrote Oregon State University fisheries professor, Dr. Robert Lackey in a recent paper. Lackey characterized the expenditures as “guilt money” which makes people feel good without addressing the fundamental challenges facing salmon. Lackey criticized those calling for more studies, claiming “salmon are amongst the most studied fish species in the world.” 

His comments were a response to wild salmon recovery efforts in the U.S., however many of the same issues apply in B.C.

Lackey calls for substantive public policy changes and said successful wild salmon recovery must address “overarching and undisputed realities,” including the following: 

  • Massive declines of wild stocks since the 1850s. 
  • Hatcheries have not replaced wild stock production, but are probably necessary for fisheries to continue.
  • There is an inverse relationship between human population growth and salmon decline.
  • We know what to do but lack the political will to do it.
  • Salmon recovery will not get easier as time passes.

Protect waterways, protect salmon

According to those who engage in ground-level salmon restoration, there are relatively inexpensive measures that can be taken to produce positive results in the short and medium terms.

“The lack of adequate oversight for residential development as one of today’s biggest threats to salmon.”

Ian Bruce

Ian Bruce is a registered professional biologist with the Peninsula Stream Society, an umbrella group specializing in small stream restoration and salmon recovery in Greater Victoria.

“The lack of adequate oversight for residential development is one of today’s biggest threats to salmon,” said Bruce. He recommends reconnecting side channels with streams and rivers wherever possible as a cost-effective way to assist salmon and manage water.

Bruce laid out a recovery template: New development should not occur near watercourses. Instead, parks, playing fields and golf courses should be located next to streams, rivers and side-channels with residential and commercial development further away. This will provide safer flood habitat for salmon and other fish while allowing areas for floodwater to disperse.

If residential development was further from waterways, it would reduce erosion damage from flooding like that caused on Millstream Creek last year.
[Photo Ian Bruce]

Bruce encouraged the public to identify off-channel habitats and report their locations to government agencies for protection and restoration. 

“Band-aids” won’t work

Tom Rutherford is a retired DFO stream restoration and enhancement community advisor who favours a “whole watershed-based” restoration.

“Development of green downstream infrastructure is unwise if upstream land use threatens those investments,” cautioned Rutherford, adding “band-aid approaches will be ripped off quickly” if severe weather-related consequences persist. 

“Band-aid approaches will be ripped off quickly.”

Tom Rutherford

Pressing upstream concerns include residential and commercial development, road building, culvert design, storm run-off, mining, logging, water extraction, agriculture and pollution. 

Dams, part of the solution

Dams have a history of obliterating salmon runs. However, in an odd role reversal, they can also contribute to salmon recovery. The capacity to store water allows a dam to augment stream flows when salmon need it.

Victoria’s Capital Regional District (CRD) water management is a good example of how this works. The plan is to store as much water as possible in reservoirs and lakes within its 11,000 hectare Water Supply Area. 

“We want to be good partners with regional stakeholders.”

Christoph Moch

“The CRD has been releasing water as needed for fisheries and environmental flows since 1994. It’s been part of their collaboration with DFO and the Goldstream River’s Howard English hatchery,” said Christoph Moch, water quality and demand manager for the district.

The CRD also provides seasonal water to the Sooke River and two hatcheries on Charters Creek. “We want to be good partners with regional stakeholders. So long as there is no critical shortage of drinking water, the CRD will strive to ensure there is water for other uses including salmon,” Moch said.

In 2004, the CRD completed a reservoir expansion that raised the water level by six metres, increasing storage capacity from 57 to 96 million cubic meters. That decision has proven insightful given the current climate trajectory.

Cowichan Lake weir. [Photo Tom Davis]

Weirs, or mini-dams, are less damaging because salmon can often swim over them during high flows, or via engineered by-pass channels. If the channels are built to replicate nature, they can increase spawning and rearing habitat. Weirs are an effective way to greatly increase water storage capacity without adding much structural height.

For example, Crofton’s Catalyst Paper manages the outflow weir at Cowichan Lake. According to their environment manager, Brian Houle, one centimetre of additional lake height equals one day of water released at seven cubic meters per second. The weir’s current height is 97 centimetres. There is a proposal to add 70 centimetres, resulting in 70 additional days of water release capacity.  

Hatchery better practices

Early salmon hatcheries were crude, production-based operations, without thought to consequences on wild salmon and salmon genetics. This has contributed to significant hatchery opposition. While marginal hatchery practices still exist, technology is rapidly moving hatcheries towards best practices, including salmon stock genetic preservation.

“Hatcheries will increasingly play a significant role in the future survival of salmon.”

Peter McCully

Peter McCully has been the Howard English hatchery’s technical advisor since the 1990s. The hatchery maintains a balance between producing salmon, supporting regional stream recovery, facilitating salmon education in classrooms, and co-venturing on university-level fish research.

“Considering the challenges of climate change and habitat loss, hatcheries will increasingly play a significant role in the future survival of salmon,” McCully said.

Rebuilding salmon will depend on embracing comprehensive, proven recovery strategies implemented by those with practical and professional ground-level experience.

They know what to do, as professor Lackey pointed out, now it’s a matter of political will.