Once a dominant species in the Ottawa River—having travelled all the way from the Sargasso Sea—local eels are now in serious decline. A recent collaborative effort to begin modifying lethal power dams to help them get home safely may be their last hope

 

 

IT’S A LONGSTANDING DEBATE in conservation circles: how much to emphasize protecting “charismatic species” like polar bears, wolves and whales versus focusing on all threatened wildlife and their habitats?

From a fundraising perspective, high-profile creatures attract more public support. But there’s also an important ecological case to be made that saving top predators and other once-abundant, dominant species has greater ultimate value. Not only do these animals typically have the largest ranges, but ecosystems have been shown to be far healthier when they are present.

All of which makes the American eel (Anguilla rostrata) an interesting conundrum. Hatched from eggs laid in the Sargasso Sea in the mid-Atlantic Ocean, its range in Canada as a juvenile and adult includes east coast estuaries and freshwater lakes and rivers accessible from the Atlantic as far west as Lake Ontario and the Ottawa River. In Ontario, the American eel, which lives about 25 years on average, was once among the most common fish species. But since the 1970s, its population has fallen by an estimated 99 per cent. The primary factor: dams and power generating stations built on the St. Lawrence and Ottawa rivers and in most large tributaries. They impede the upriver migration of juvenile eels and chew up many mature adult eels when they’re sucked into the turbines as they attempt to migrate downstream to return to the ocean to reproduce.

The province listed the American eel as endangered under the Endangered Species Act in 2008 but is years late in finalizing an action plan for its protection and recovery. COSEWIC, the committee that identifies species at risk in Canada, declared the eel threatened in 2012, but the federal Department of Fisheries and Oceans is itself years late in deciding if it will list it under the federal Species at Risk Act. And despite repeated, urgent calls for more action by conservation organizations and their supporters, scientists, local First Nations and advocates like the Environmental Commissioner of Ontario, there’s been no larger groundswell for a speedier, appropriate response.

“They’re mysterious creatures that live in the bottom of stained freshwater habitats where people don’t see them. Most people don’t even know that there are eels in Ontario, let alone that they travel here from Bermuda as babies,” says Nicolas Lapointe, senior conservation biologist in freshwater ecology with the Canadian Wildlife Federation, which has operated an American eel research program on the Ottawa River since 2012. “There’s also a cultural influence, where a lot of North Americans [have] this weird hatred of snakes or anything that looks like a snake.”

In short, it’s hard to think of a better poster species for severely endangered yet non-charismatic wildlife than the American eel.

But here’s the thing. American eels are—or, more accurately, were—a major predator in their ecosystem. Adult eels feed on small fish, frogs and a range of invertebrates, and given their former numbers, it’s not hard to see how their relatively sudden absence created a major ecological imbalance. “It’s one thing when you have a small, rare minnow that becomes endangered—and that’s an issue we’re concerned about—but when you have one of the most common species in a large ecosystem like Lake Ontario or the Ottawa River getting to less than one per cent of their abundance, that’s a real [problem],” says Lapointe.

For all of these reasons, he is hopeful 2018 will mark a turning point for American eel conservation. The main focus of that optimism: Energy Ottawa Inc.’s just-completed Chaudière Generating Station, a 29-megawatt hydroelectric power station next to the Chaudière dam at the Chaudière Falls on the Ottawa River just above Parliament Hill. One of six generating stations on the site, it’s the first—not just here, but on the entire Ottawa-St. Lawrence system—to incorporate design features that permit safe downstream passage for American eels. “It’s very significant,” says Lapointe. “They’re trying to do the right thing for eels.”

He also hopes the work will be a precursor to similar measures at other generating stations as they are replaced and rebuilt in years to come. While it’s too expensive “to go in and redesign a facility in the middle of its lifecycle,” says Lapointe, “we want to see that start happening whenever any facility is built or retrofitted.”

At Chaudière, three key features work in tandem to protect eels that come downriver and enter the station’s intake, according to Sasha McCulloch, an engineering intern with Energy Ottawa and point-person for the company’s eel mitigation and monitoring work.

First, a widened intake channel reduces the speed of the water flow “so that they can get out of that channel if they want to,” she says.

Second, during the July-to-September migration season, the company will install special screens on top of the “trash rack” grate that prevents large debris from entering the turbines. Those screens have tight, 20-millimetre openings “small enough that a mature American eel would not be able to go through.”

Finally, in a wall on one side of the intake channel, there is a “fish bypass” system. As McCulloch explains: “These are essentially just two pipes that have water continuously flowing through them. There’s one towards the lower section of the intake, one towards the top, giving the fish two options.” Eels, or any other fish, that enter those pipes will be carried through the complex and ultimately expelled, unharmed, into the river below the dam. (At the same time, to help juvenile eels make their way upriver, a permanent eel ladder has also been installed.)

 

SAFE ZONE: The intake section for the new generating station at Chaudière Falls on the Ottawa River, with special tight-mesh “trash rack” to prevent downstream-bound migrating eels from being sucked into the turbines. On left wall, there are two bypass tubes that eels can enter to travel through the dam and be released below unharmed

 

BEYOND THE construction itself, Energy Ottawa (which is a municipally owned power generating firm) has teamed up with CWF and Carleton University on a related three-year eel research project. It involves fitting eels above the dam with acoustic transmitters and installing two arrays of acoustic receivers above and below the facility. The system uses acoustic telemetry to track eels as they approach, select a route—either a large spillway in mid-river, the new plant’s intake (both relatively safe) or one of the five other station intakes (not safe)—and measure mortality rates as they exit the complex.

“Eels have choices as to where they pass when they come downstream,” explains Lapointe. “This system lets us figure out what channel each eel first appeared in and whether they survived passage if they took that route.” This research will help Energy Ottawa refine the measures it takes to protect the eels. “We need to know where they’re going so that we can best implement strategies to protect them,” McCulloch says.

But the research faces a challenge. The study launched last year, before the new power station was online. CWF’s goal was to capture and tag at least 20 adult eels above the dam. It trapped only nine. And only one of those migrated. “Those other eight eels have transmitters that will continue transmitting in future years, so we’ll keep monitoring to see when they do out-migrate,” says Lapointe. “But this is sort of the reality of working with endangered species. It can be very hard to get enough individuals to do research on.”

This year’s plan is to try to capture another 20 eels and augment that with up to 30 eels purchased live from fish markets in the lower St. Lawrence, where an eel fishery still operates, or from commercial fisherman on the lower Ottawa River and in Lake Ontario, who catch eels as by-catch.

Those eels would then be transported to a point above the Chaudière dam, tagged and released. “These won’t be native Ottawa River eels, but they would be a good surrogate for addressing our questions,” says Lapointe.

Physical transport of eels above and below dams is not without precedent. CWF, in partnership with other local conservation organizations, has on several occasions collected and transported to the upper Ottawa juvenile eels captured in the eel ladder at Hydro-Québec’s Beauharnois dam on the St. Lawrence, just to the southwest of Montreal. And Ontario Power Generation, which operates the R.H. Saunders Generation Station at the Moses-Saunders dam on the St. Lawrence near Cornwall, has an agreement in place with the provincial Ministry of Natural Resources and Forestry to trap adult eels above the dam and release them downriver, below the Beauharnois dam, so they can continue migrating towards the sea.

That there are still any naturally occurring adult American eels above the Chaudière dam at all is, in fact, something of a mystery. Juvenile eels that enter the Ottawa River face a massive obstacle in the form of Hydro-Québec’s Carillon Generating Station dam, 20 kilometres from the mouth of the Ottawa River. That dam, opened in 1962, has no eel ladder, which means eels must find another way to bypass it and navigate the 18-metre hydraulic head.

How do they do it? “We don’t know,” says Lapointe. “The suspicion is that they’re using a Parks Canada lock system, a canal that gets around the dam.”

Until the recent installation of the eel ladder at Chaudière, eels that got past Carillon faced the same problem there, with no canal for a bypass. Yet according to Lapointe, earlier acoustic telemetry work by CWF above and below the dam found that two of 45 eels tagged below Chaudière made their way past. “No one has any clue how they do that,” he says. “There may be some place where they can swim upstream. There may be crevices they find through the dam, or maybe they actually get out [of the river] on sloping ground on rainy nights and wriggle their way up. Eels are well known to do that—young eels are amazing climbers—but it’s easier along the sides of a rapid than it is in an urban environment like Chaudière.”

A fish that walks on land in the heart of the nation’s capital? Who says eels aren’t charismatic?

THERE IS A SECOND potential source of optimism for the American eel in 2018, but it depends on decisions currently being made within the Ontario government. In January, the comment period ended on the government’s draft response statement to the American eel recovery strategy published in 2013. The recovery strategy—a requirement for every species listed under the Endangered Species Act—is “a science-based analysis of what it would take to recover the species,” explains Lapointe, whereas the response statement “adds a socioeconomic filter and says what the government thinks it can realistically do to implement parts of the recovery strategy.”

According to CWF and other conservation groups, including Ottawa Riverkeeper, Ontario Nature and Ontario Rivers Alliance, the last draft of the response statement failed the eel in several ways. For example, says Lapointe, while the statement did call on dam operators to provide downstream mitigation and upstream passage where none exists, it “delays any specific requirements for another three years” pending the results of more study to devise a “passage-implementation planning process.” The time to delay action for more extended study is past, argues Lapointe. “We’re now  at a stage where we need to use our best available knowledge and best available tools to actually start taking action.”

There are other regulatory levers. For example, the eel mitigation measures in the new Chaudière station were required for project approval under the federal Fisheries Act, which prohibits serious harm to fish, including damaging fish habitat or killing fish without a permit. Unfortunately, the Department of Fisheries and Oceans rarely holds hydropower producers accountable under the act, even though their facilities prevent fish passage and kill fish in their turbines, says Lapointe. Hence the need for effective action under the Endangered Species Act. “It’s not realistic to think they’ll stop killing eels in 10, 20 or even 50 years,” he says. “But they can reduce how many eels they are killing. And the government response statement is a key opportunity to set a standard for what degree of reduction in mortality would be acceptable.”

To that end, Lapointe says there are two measures that could be implemented immediately.

The first would be to expand trapping of adult eels above the dams and transporting them downstream to avoid mutilation in the turbines—where mortality rates typically run between 20 and 40 per cent. Few power station operators are doing this now, says Lapointe, while the program Ontario Power Generation has been running at the Saunders dam, however commendable, is inadequate. “The Saunders dam kills about 26 per cent of all eels that leave Lake Ontario. The trap-and-transport work they were doing was saving less than two per cent of those eels.”

The other conservation measure that could be implemented immediately would be to require the power companies to turn off their turbines at night during the eels’ migration season and instead divert the water through a spillway. Says Lapointe: “We know that from July to September, that’s when these big eels leave the systems, and 75 per cent of them leave at night. So if they just didn’t run the turbines at night, 75 per cent of the eels would have safe passage back. If they even didn’t run the turbines at night half the summer, you’d then have 37 per cent of the eels saved.

“We know that nighttime is not peak time for power demand. So it can be done.”

CWF and others argued for these measures in their comments to the Ontario government, and Lapointe has his fingers crossed that they’ll make the cut in the final document. The principles of trap-and-transport, water management and retrofits during renovation were noted in the penultimate draft, “but they hadn’t provided a timeline saying this needs to happen immediately, nor had they quantified the degree to which it needs to happen.”

Construction of eel ladders where they don’t yet exist is just as important as downstream mitigation, adds Lapointe. “Both are necessary.” If he could pick one spot to start, it would probably be the Carillon dam, as that would help restore access to the Ottawa River. On some tributaries farther upriver, such as the Mississippi, where there are several separate power facilities for adult eels to navigate on the way down, it might make sense to wait until some downstream mitigation is in place. But even then, he notes, the American eel’s long lifespan weighs against any delays.

“If we put in ladders today, that gives us another 20 years to develop technology and figure out ways to get them downstream safely,” says Lapointe. “Refusing to put in ladders today because we’re worried about downstream mortality means we’re saying we really don’t expect anything to change in the next 20 years. And that’s really unacceptable.”

This article was originally published in the March-April 2018 issue of Canadian Wildlife magazine.

Illustration courtesy of Lynn Scurfield; photography courtesy of Energy Ottawa