Atlantic Whitefish

The Crisis Fish

Another bid to save our most endangered species.

It was the spring of 2016 when I saw my first Atlantic whitefish, an infant, squirming and spasming in the holding tank of a rotary screw trap. It was such an inconspicuous creature, indistinguishable from the myriad minnows of my youth, but I knew better than to take this sighting for granted. In that moment, I became one of the very few Canadians ever to see this species alive.

The Atlantic whitefish is Canada’s most imperiled species. Others vie for the title, of course, like the North Atlantic White whale, Black-Footed ferret, Whooping crane and Blanding’s turtle, but even among endangered species, Atlantic whitefish stand out. Their entire global population has been restricted to a single watershed since 1982 – Nova Scotia’s Petite Rivière – its three interconnecting lakes their only stronghold against extinction.

Atlantic Whitefish
Atlantic Whitefish: Photo by Ian Manning

For over a century, these lakes – Hebb, Milipsigate and Minamkeak – have played host to several impassable dams, preventing any whitefish venturing downstream from returning home. In the last few decades, invasive Smallmouth bass and Chain pickerel have infested the watershed, preying on whitefish big and small, driving their global population down to a few hundred at best, a few dozen at worst. Their stronghold is crumbling.

It would be unfair to say our federal government has entirely failed the Atlantic whitefish. They’ve funded electrofishing expeditions into this watershed for years now, paralyzing and removing as many invasive pickerel and bass as possible. And in 2000 they began a captive breeding program aimed at restocking the Petite Rivière, though it was ultimately marred by the sporadic whims of the Harper government and cancelled in 2012 before it could produce meaningful results. What I will say is that the initiative, the motivation, indeed the zeal to rescue this species has consistently come from outside of government. Were these whitefish left to the ebb and flow of political will, I am confident our last and best chance to save the species would never have materialized, as it did in 2018.

That spring, and every spring thereafter, the Bluenose Coastal Action Foundation (a Nova Scotian charity carrying out most on-the-ground conservation for this species) has collected infant Atlantic whitefish caught throughout the Petite Rivière and brought them to Dalhousie University, where they’ve been raised to maturity in this institution’s state-of-the-art research aquarium – Aquatron. Here, these critically endangered fish have begun to breed, beyond the reach of pickerel or bass, climbing from several dozen individuals to a captive population of over a thousand.

Aquatron is where I saw living Atlantic whitefish for the second time in 2018, a few dozen individuals swimming spiritedly in a tank they would soon outgrow. Today, these whitefish are straining Aquatron’s capacity and teaching Dalhousie academics more about this peculiar fish than was previously possible to learn. Paul Bentzen, a fish ecologist, geneticist, and chair of Dalhousie’s department of biology, was the first to volunteer space in Aquatron to these refugee whitefish, and soon, he said, they will play their part in rescuing the species.

Dr. Paul Bentzen
Dr. Paul Bentzen. Photo by Zack Metcalfe

The best hope for the Atlantic whitefish is still the Petite Rivière, he said. Even though several of its lakes are crippled by invasive fish and impassable dams, this watershed remains the only place on Earth to have supported Atlantic whitefish, continuously, since glaciation. Whatever its flaws, the Petite Rivière mustn’t be abandoned, and will be the chief destination for the products of Aquatron’s breeding program.

The Atlantic whitefish is “anadromous” under natural conditions – born in freshwater, maturing in the open ocean, then returning to freshwater in order to spawn – but for over a century, the only whitefish to survive and reproduce have been those who’ve stayed put, tempering their downstream ambitions and remaining behind the several dams of the Petite Rivière. Even though a fish ladder was built for their benefit in 2012 by the adjacent Town of Bridgewater, there have been too few left to use it. The first goal of the captive breeding program, therefore, will be to re-establish the oceangoing nature of the Atlantic whitefish, said Bentzen, introducing thousands of hatchlings to Hebb Lake in hopes that they’ll swim downstream to the Atlantic Ocean, then return, mature, by way of the fish ladder.

Whitefish imprint on the rivers of their birth. No matter how many years they spend touring the open ocean, when it comes time to breed they will return to their home river with fanatical devotion, recognizing it by smell. The whitefish already hatched in Aquatron have imprinted instead on the filtered waters of the Halifax Regional Municipality, so can’t be released into the wild. Their unhatched eggs are another story.

At this moment, a whitefish hatchery is being constructed alongside the Petite Rivière, funded by the federal Department of Fisheries and Oceans, run by the Bluenose Coastal Action Foundation, and supplied with eggs from Dalhousie University’s captive stock, a splendid display of partnership and shared responsibility. The hatchery will draw water directly from the Petite Rivière so that its whitefish will imprint on the proper ecosystem. Precisely how and at what age its whitefish will be released into the watershed is the subject of ongoing discussions, but initial attempts could begin this year, continuing earnestly in 2023.

“Releases are rarely overnight successes,” said Bentzen. “As far as we know, no Atlantic whitefish has completed that lifecycle of going to sea, coming back and spawning for a century or more.”

If whitefish anadromy is successfully re-established in the Petite Rivière, it is fair to suppose the breeding success of the species will begin to improve, bolstered by adult whitefish hardened in the Atlantic Ocean. With continued management of invasive pickerel and bass, perhaps whitefish could hold the Petite Rivière, but in order to better guard against extinction, the species must be established in other watersheds entirely, and anyone looking closely at the streamside hatchery being built along the Petite Rivière will notice something strange – it has wheels.

Introducing Atlantic whitefish elsewhere is not a new idea. It was even attempted from 2005-2008 in the course of the federal government’s original captive breeding program, but their choice of watershed – Anderson Lake in Dartmouth, Nova Scotia – was poorly chosen, and so the effort failed.

Surveys, carried out by the Department of Fisheries and Oceans as well as Dalhousie University, are presently underway to find an appropriate new home for the Atlantic whitefish. If any are chosen, with suitable habitat characteristics, species compositions and a complete lack of invasive fish, the streamside hatchery of the Petite Rivière could be moved to seed new watersheds. At his most optimistic, Bentzen said this could happen as early as 2023, but, of course, his is not the only voice at the table.

The hatchery won’t just sport wheels. It will also be painted, lavishly, with the likeness of an Atlantic whitefish fighting the current, and the species’ name written in English, French, Mi’kmawi’simk and Latin. In some way or another, its work will be made visible to the public, so anyone in the neighbourhood can stop by and see what I have seen – young Atlantic whitefish, swimming in temporary tanks, ready to reclaim their home and perhaps establish new homes altogether. This hatchery is likely the last hope of the Atlantic whitefish. We would do well to keep that in mind.

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Eastern Perspectives

Zack Metcalfe is a freelance journalist, columnist and author based in the Maritimes.