Unsafe passage

A new technical study estimates as much as a third of some juvenile wild salmon could be killed while passing through the Whitehorse dam, with the facilitys turbines potentially dealing the fish deadly blows or inflicting other traumas.

The study is connected to Yukon Energy working to renew its 25-year water use licence, which expires in 2025. As part of that process, Yukon Energy, the Carcross/Tagish First Nation, the Kwanlin Dn First Nation and Taan Kwchn Council formed a working group to, among other things, assess salmon mortality at the dam.

The study, spurred by the First Nations, was prepared for the Crown corporations planning branch and has yet to be publicly released. CBC News obtained a copy through an access to information request.

The study was prepared by Ecofish, a B.C.-based environmental consulting firm, under contract for Yukon Energy. Lead author William Twardek was not available to talk about the research.

Built in 1958, Yukon Energys dam on the Yukon River is a crucial piece of infrastructure, generating enough power to supply on-grid residents with roughly 80 per cent of their electricity during the summer equivalent to lighting up roughly one million 40 watt light bulbs. The dam has four turbines, a spillway and, at roughly 366 metres, what the company boasts is the longest wooden fish ladder in the world.

The number of chinook salmon swimming back into Canadian waters has been declining for decades. The past two years have yielded some of the worst tallies recorded on the Yukon River. Last year, only 12,000 chinook reached the Canadian border, a number paling in comparison to the predictions.

Theories abound, some more researched than others: deadly parasites, warmer water temperatures linked to climate change, overfishing.

The reasons for the chinooks decline are complex and elusive. These salmon have a massive range. Alevin emerge from eggs nestled in shallow, freshwater gravel beds, nests called redds. The fish develop into fry and then, as juveniles, will travel thousands of kilometres to the ocean. As mature adults, they return to spawn where they were born. And because some of those ancient spawning grounds are located upstream from the dam, that means some adult chinook must traverse the Whitehorse dam not once, but twice.

Several sources told CBC News the main spawning area for chinook is upper Michie Creek, which flows into the MClintock River and, from there, enters the mainstem of the Yukon River.

While the new study states broader ecological problems are likely behind the declines, it raises questions and offers potentially important insights. Yukon First Nations, who have harvested salmon for millennia, have long raised concerns about the dam and some say it could be affecting the fish much more than has been understood.

Sean Smith, chief of the Kwanlin Dn First Nation in Whitehorse, said while adult chinook salmon swimming upstream to spawn have been the focus of much research lately, relatively little has been done in the Yukon on the young fish some no bigger than the size of your outstretched hand migrating the other way, downstream and into the Bering Sea.

The gaps in research, Smith said, are part of a much bigger story that still needs to be told, documented and understood by scientists, politicians and the broader community.

Studies like this latest one, Smith said, could also help reckon with the past.

Theres been things that have happened over the last 120-odd years of colonization happening here impacts directly on families that use the salmon for subsistence fishing, for their livelihood, for their culture and teaching the younger generations on a very important way to live, he said.

When talking about harvesting salmon in the traditional way, Smith speaks in the past tense. Thats because some Yukon First Nations, including Kwanlin Dn, have long abstained from harvesting chinook, to give the species a stronger chance to recover.

Reconciliation is what sort of things can we address as to historical impacts to our people, the impacts to the river itself, but to all the other things within our territory that survive off the salmon.

Amanda Leas, the chief of the Taan Kwchn Council, said before the dam was built, fish camps lined the banks of that stretch of the Yukon River. Some of those camps belonged to Leass family. The dam, she said, displaced families, and cultural practices.

And the impacts persist, as illustrated by the study, Leas said.

Were shocked, she said, but we werent surprised.

This is something that we have been talking about for a number of years and now is our opportunity to fix it.

The study looks at three groups of chinook wild fry, wild yearlings and hatchery fry and estimates mortality for each.

Of the salmon passing through the area of the dam specifically, the turbines, spillway or fish ladder the report estimates 26 per cent of the youngest wild fish died, roughly 34 per cent of salmon at least a year old died, and 23 per cent of the hatchery fry died.

Based on the amount of water flowing through the dam, most fish are estimated to go through the spillway, but still, a significant proportion could also enter the turbines.

The study doesnt reflect Yukon River chinook that spawn downstream of the dam.

Little research has been conducted about the impact of the dams turbines. While a study from the 1970s estimated roughly two percent of fry and 16 per cent for yearling salmon were killed by the turbines, that study has been criticized by researchers as incomplete.

Reviewing studies conducted in places like the extensively dammed Columbia River and its tributaries, researchers calculated general mortality estimates and applied them to the dam in Whitehorse.

During the peak migration last summer, estimated to be between June 28 and July 7, researchers also used sonar to study 72 fish passing downstream at different openings. That includes intakes that lead to the turbines and to the spillway, a structure where excess water is sent downriver sometimes at great volumes.

To figure out whether juvenile salmon could, in fact, be harmed by the inner workings of the dam, scientists deployed mechanical sensors referred to in the study as robotic fish roughly the same size and weight of the studied salmon down two turbine intakes.

According to the study, all of them were either lost or destroyed during fieldwork. In fact, one was cut in half by a turbine blade.

Data collected from the sensors put estimates of blade strike mortality substantially higher than other included predictions, the study states.

For yearling salmon that travelled through the newest turbine on-site built in 1985 the estimate could be as high as 51 per cent.

The dams turbines present the greatest risk of death, the study suggests. When fish pass through they can get struck by revolving blades, stuck in gaps, or suffer from barotrauma, injuries brought on by sudden changes in air or water pressure.

Turbine strikes are typically the leading cause of mechanical damage, and it is assumed that most fish struck by blades will die, the report says. The likelihood of [a] blade strike is primarily dependent on the type of turbine, number and size of blades, fish size, discharge, and rotations per minute, all of which, it continues, increase the risk of death to fish.

Turbine blade strikes may not be the only thing killing the fish, which could be sent through the intakes at great speeds.The study says abrasion, hitting walls and getting stuck in machinery should be the focus of more research.
 

The study also looks at whether animals such as gulls, osprey and Northern pike around the dam are contributing to the chinook declines. It finds little, if any, collected evidence to suggest the salmon are being killed in high numbers by predators when they pass through the dam. Still, the study states more research is needed.

The study also suggests juvenile chinook salmon mortality rates could be higher than those found elsewhere. Based on a literature review of dams of roughly the same size located mainly in the U.S., the study suggests the rate could be roughly four per cent.

CBC News shared a copy of the study with Al von Finster, a well-known fish biologist who formerly chaired the Yukon Salmon Sub-Committee. He told CBC News the estimates in the study are quite high.

He said there are still many unknowns, including the behaviour of juvenile chinook salmon higher upstream, which need to be addressed in order to fully understand the implications of the study.

Von Finster also questions the researchers use of estimates from other places for instance, the drainage of the Columbia River to arrive at estimates for the Whitehorse dam.

Theres two things. The Columbia River is a long way away from here, and we have chinook salmon in both of them, but our chinook salmon dont necessarily behave like the fish in the Columbia do. Thats just a reflection of local adaptation. Its a reflection of a species thats very flexible, thats not held tightly to the use of certain habitats but can use a number of different habitats.

Von Finster also said an enormous amount of literature has been dedicated to studying the fish along the Columbia River. The same cant be said for the area around the Whitehorse dam and beyond.

The number of juvenile chinook salmon migrating past the Whitehorse dam depends on a complex matrix of things that varies wildly year-to-year. That includes differences in water levels, temperature and time of year.

One 1998 study, co-authored by von Finster, states very little information has been documented regarding the seasonal movement of the [juvenile chinook salmon] during their annual downstream migration to the ocean.

The study also states its generally accepted that a substantial number of the ocean-bound fish move through turbines and are killed, though unclear to what extent.

Michael Muller, Yukon Energys vice president of planning, environment, health and safety, told CBC News all energy generation has impacts.

I think one of the things thats really powerful is that were looking to both re-license but also operate [the dam] and manage it in a new and better way, he said.

What our focus is on is trying to understand how those fish end up in the turbines, whether we can redirect them to the spillway. Our focus is really on developing some understanding and mitigation.

More research on the issue is planned for next summer, Muller said. That could include, he said, increasing the sample size, expanding the use of sensor fish and studying, more fulsomely, where the salmon are originating from, as well as how they use the waterway.

Are they in the top of the water column, bottom, to the edges, are they in the middle of the reservoir? he said.

Thatll inform the kinds of mitigation.

More than six decades after that dam was constructed, its still unclear what proportion of the juvenile salmon actually use the fish ladder for safer passage downstream.

Notably, we did not assess whether salmon were using the fishway, though previous discussions with the hatchery staff suggest very few juvenile salmon move through the fishway, the study states.

Maria Benoit, the aa Shad Hen of the Carcross/Tagish First Nation (C/TFN), told CBC News the ladder has long been problematic. For one thing, she said its opening is too small, raising the prospect that fish and not just salmon, but whitefish, grayling and lake trout will miss the entrance altogether and end up injured or dead.

According to the study, the ladders opening is a two-by-two metre square. For comparison, the diameter of one turbine intake is about 6 metres.

C/TFN wants a total redo of that fish ladder, Benoit said, and it needs to be opened up all year-round. Weve asked [Yukon Energy] to do that, and have to keep asking them.

The ladder, originally built of creosote-coated wood in 1959, hasnt changed since it was first built, she said.

Were tired of talking.

Asked about changes at the fish ladder, a Yukon Energy spokesperson said in an email that fish are no longer held in the viewing chamber, and gates stay open around the clock.

Previously, we used to hold fish in the chamber so that we could count and sex them, however [we] now do this via a counting camera, the spokesperson wrote.

To draw more fish to the ladders opening, the spokesperson also said the company has adjusted flows.

The First Nations demands go well beyond the fish ladder.

We want to see salmon coming back to our traditional territory, Benoit said.

After all, chinook were once plentiful in the area, but now citizens havent seen the fish cruising through the region for more than 50 years, a turning point Benoit blames on the dam.

We dont get salmon at all on this side of the dam, she said, referring to the First Nations traditional territory, upstream of the facility. Our people have to buy salmon [from the Taku River and places in Alaska] and we have it shipped to us.

And thats only two salmon per family, per household. Its not very much.

The study says adjusting the amount of water discharged through the dam during peak migration could help lessen any impacts on the fish. It says making that change could help increase the proportion of fish using the least harmful routes the spillway, or the fish ladder.

Other mitigations include shepherding the salmon into safer routes by using lights, screens and bubble curtains basically, a wall of bubbles that scare fish away. The latter has been used at least once in the Yukon, to help protect lake trout while crews work to replace Teslins aging bridge.

The study also addresses how turbines could be redesigned to minimize the number of fish getting hit by the blades. That includes having fewer blades per turbine, spreading them out and ensuring edges of blades are blunt, not sharp.

The study highlights what it calls fish friendly turbines. According to one study by the Electric Power Research Institute, such turbines could increase fish passage survival to roughly 98 per cent for fish measuring at least 200 millimetres. For comparison, all juvenile salmon studied with sonar that were featured in the study on the Whitehorse dam were an average size of 221 mm.

Among other things, the study urges more research into behavioural patterns of juvenile chinook. That includes confirming the timing of their migration and route choice. To verify that information, researchers suggest longer-term sonar projects at the dam. Considering sensors were only sent down two turbine intakes, the study also recommends the project be expanded to include the other two turbines.

Sensor fish are also particularly useful for evaluating relative harm, and could be used to assess the effectiveness of potential design and operational changes, the study states.

Asked whether Yukon Energy will implement any of those ideas, Muller said its too early to say.

Smith, the chief of the Kwanlin Dn First Nation, said studies are only as good as the change they cause. One such example could be restoring spawning grounds, some of which were wiped out when the dam was built. The construction raised water levels so much they flooded the area upriver of the dam and created what is now known as Schwatka Lake, a reservoir.

Thats the important kind of zone thats been identified as an opportunity to enhance and to support chinook salmon spawning, he said.

We care about the salmon because theyre like us. We are salmon people.

Producer: Kanina Holmes