A provincewide drought this summer dried up B.C. rivers and jeopardized the survival of already stressed salmon stocks.
But for the first time, localized salmon SWAT teams mobilized quickly to tackle hot spots of concern on rivers across B.C. as part of a new pilot project, said Jane Pendray, manager of the Pacific Salmon Foundation’s (PSF) climate adaptation program.
Various First Nations and local conservation groups scrambled to help salmon surmount drought conditions. Some armed themselves with shovels or heavy excavators to dig escape channels for trapped fish, while another group experimented with providing fish with some breathing room.
“These organizations, because they’re on the ground and know what's going on, can identify problems right off the bat and bring those to us and say, ‘Here's an issue. We have an idea of what to do to fix it,’” Pendray said.
PSF and the province kicked in funding and collaborated with local partners and Fisheries and Oceans Canada (DFO) to tackle the salmon emergencies specific to their regions, she said.
Salmon gasping for air on the Tsolum
One particularly innovative project surfaced on the drought-stricken Tsolum River on eastern Vancouver Island: to provide suffocating salmon the breath of life by aerating spots where the fish gather, Pendray said.
The Tsolum, along with more than 85 per cent of B.C.’s water basins, suffered unprecedented and severe drought this summer. By mid-July, the river hit Level 5 on the provincial drought scale — the most extreme rating that indicates adverse impacts on fish health, ecosystems or society are certain.
As river levels drop during drought, water temperatures soar and oxygen levels plummet, taxing the survival of juvenile and spawning adult fish, said Katie Gair, Tsolum River Restoration Society (TRRS) program co-ordinator.
TRRS, a stewardship group consisting mostly of volunteers and citizen scientists who work with K'ómoks First Nation Guardians to protect salmon, were worried about fish being forced to rely on ever-shrinking and often disconnected pools of water, Gair said.
As a result, the group tested different aeration systems to boost oxygen levels in the water in key gathering spots, she said.
Aeration systems are typically used to make bubbles that provide air to fish in contained aquariums, ponds or aquaculture tanks, but it wasn’t clear if they’d be effective in a natural environment and open river system.
The TRRS was eager to experiment given the current drought and past experiences, Gair said.
The Tsolum has a history of low water levels and has experienced drought conditions for the past three years. In those instances, there wasn’t enough water running through the gravel beds or feeding small pools to maintain adequate oxygen levels for fish.
In 2021, a massive die-off involving upwards of 1,000 spawning pink salmon occurred after the adult fish massed at a certain spot on the river and used up all the available oxygen.
“So we were hoping we could aerate [the water] and supplement any school of fish that were piling up so they didn't suffocate and exhaust themselves,” Gair said.
Juvenile coho that live in the river for the first year of their life and trout can also pay the price when water levels plummet, causing lethal temperatures and oxygen levels, she said.
The TRRS team tested the aerators in spots where spawning pink salmon gathered waiting for the right time or river conditions to continue their journey upstream or where juvenile coho congregate in search of cooler water.
To aerate the water, a generator and compressor are attached to tubing that feeds air into two ceramic stones, producing a storm of air bubbles that releases oxygen into the water, Gair said.
The group experimented in August and September in a side channel populated with about 100 adult pink salmon at the front end of the spawning season before the rains arrived. Oxygen levels were running around 75 per cent at that time, she said.
“We were able to kick it up in a pool of fish to 100 per cent,” Gair said.
In another trial, with some tweaking, they were able to achieve a 30 per cent increase in oxygen levels.
“We were really happy with that,” Gair said.
“I think we can improve that greatly and see even better improvements.”
The team experimented with a smaller version of the system in the pools that small coho were using to stay cool, but it wasn’t as effective.
Before they could test bigger units in the coho pools or other areas where spawning pink adults gathered, fall rains got underway and raised river levels. That was good news for the salmon but put an end to field experiments until next spring, Gair said.
Some technical tweaks, such as seeing if the system can be powered by solar panels, will take place over the winter. The team will also practice assembling the system quicker to improve emergency response times, she said.
Salmon conservation overall and the new emergency tactic will depend on its Eyes on the Tsolum River program, where people who regularly walk the river report potential problems, water temperatures and other vital information to set urgent responses to assist salmon in motion, said the program’s co-ordinator Allan Chamberlain.
“Like in any SWAT system, you need some intelligence or reporting to help the response,” he said.
Gair stresses aerators are envisioned as a “stop-gap” intervention to keep salmon alive while more far-reaching and durable solutions (such as clearing debris to allow salmon to move upriver or restoration efforts to identify and improve refuge areas for coho) are devised.
Despite the promising initial results, no system would likely be able to pump enough oxygen into water to sustain the needs of thousands of adult fish over long periods of time.
“It’s just until we can remove a blockage or confirm with DFO and see if we could do something else to get those fish to move along.”
Other Salmon SWAT teams in B.C. also provided effective emergency interventions, Pendray said.
The DFO and the Secwepemc Fisheries Commission brought in a large excavator to dig a channel to span a dry section of the Tranquille River near Kamloops to allow salmon to migrate upstream to their spawning grounds. The Simpcw First Nation dug small but deep channels to allow salmon fry from the hatchery to make their way into the North Thompson watershed.
However, Pendray stressed emergency solutions need to be partnered with a comprehensive approach to protect salmon from drought on the West Coast.
Hotter, drier summers paired with regional drought are increasingly common as the climate crisis advances, but this year’s impacts started early and were severe and widespread and ripple effects are still ongoing, Pendray said.
This summer’s crisis is still wreaking havoc on more than 40 per cent of the province’s river systems, particularly in northwest B.C. and the central Interior where severe and dangerously low water levels persist — possibly setting the stage for severe droughts next summer if not enough rain falls this winter, Pendray said.
“We are looking at what we can learn [from the projects] and do even better next year, if needed, but also how to take the next step for a strategic drought mitigation plan for salmon,” she said.
“Climate impacts on our environment and salmon need to be taken into account on a broader timescale.”