Countdown to extinction

A Dalhousie researcher steps in to help the endangered Atlantic whitefish

Time has not been kind to the Atlantic whitefish, once relatively common in southern Nova Scotia and now restricted to a single watershed in all the world: Petite Rivière, just south of Bridgewater.

Andrew Breen of the Bluenose Coastal Action Foundation has spent years on this watershed, administering the hands-on conservation keeping this last wild population from the grips of sure collapse, but in spite of his best efforts, it seems only a matter of time.

“It’s a countdown to extinction,” he says, pointing to the ongoing infestation of this watershed by invasive Chain pickerel and Smallmouth bass, specimens of which have carried the partially digested remains of Atlantic whitefish. One time, in the stomach of a Chain pickerel, Breen recovered two baby turtles, alive and well.

“We need to be looking at other watersheds free of invasive species where we can try introducing a few whitefish, somewhere they might persist and be safe,” he says. “They haven’t got much time left.”

Last spring such an effort seemed possible, when the Department of Fisheries and Oceans (DFO), instructed Breen to collect 28 infant whitefish from the Petite Rivière and store them at the Coldbrook Hatchery, an insurance policy against extinction and the possible beginnings of a captive breeding project.

Breen, and many in the conservation community, breathed a sigh of relief, knowing all eggs were no longer in one basket, until October of 2018 when DFO announced their intention to dump these whitefish back into their home watershed, citing a lack of space at their Coldbrook Hatchery.

“If it wasn’t for the intervention of Paul Bentzen, I think DFO would have put those fish back in the watershed,” says Breen. “I don’t know how much point there would have been in carrying on.”

Paul Bentzen is a fish ecologist, geneticist and chair of Dalhousie’s department of biology. He’s spent a career in service to fish, either shedding light on their lives and needs, or else advocating their protection to whomever will listen.

“When I heard these [whitefish] were going back to their lake of origin, I knew I had to stop it,” he recalls. “I knew they were going to die there. The mortality rate would be very high, if not 100% because of the pickerel and bass.”

One time he demonstrated to lawmakers that a single, at-risk species of native, landlocked smelt was actually two distinct species, each in need of drastically different recovery strategies. He’s tracked the decline of Nova Scotia’s freshwater biodiversity using the fieldwork of himself and colleagues, and is presently wrangling the funds necessary for a larger, systematic study on the subject, providing context for conservation efforts across the province. The widespread loss of native Brook trout, Striped bass, and others are firmly on his radar, and with the sturdy hand of science he’s bringing these matters to the forefront.

While not always glamorous, Bentzen is keenly aware of the biodiversity crisis playing out in the watersheds of the world, and is doing everything in his power, as a scientists and educator, to turn the tide, all the while grading papers and publishing his conclusions. An academic in demeanor, he has the curious ability to make things happen, and to date, no case has garnered more attention than his rescue of the Atlantic whitefish.

He’s paid close attention to the species’ decline these last few decades, and was fast to act when the refugees of Coldbrook Hatchery were threatened with repatriation. He called DFO in October 2018 and offered to take these whitefish himself, storing them in Dalhousie’s state-of-the-art research aquarium (Aquatron) all before securing permission from the university. Thankfully Dalhousie was on board and DFO delivered the fish in late December 2018.

With the collapse of the Petite Rivière population expected in the not-so-distant future (Bentzen puts their numbers between a few dozen to a couple hundred) these infant whitefish could represent the species’ only hope for recovery, a process Bentzen has taken upon himself to initiate.

In 2020, Bentzen and like-minded academics intend to get funding for a sizable survey of Nova Scotia’s lakes and rivers. The primary purpose of this survey would be to determine the damage of invasive Chain pickerel and Smallmouth bass to provincial watersheds, but it would also be a search for clean watersheds into which Atlantic whitefish might be introduced, thus rescuing the species. Where this funding will ultimately come from is still an open question.

“One way or another, we will do it,” he says.

Meanwhile, these whitefish are enjoying safe captivity, with ample food, veterinary care, and the keen eyes of researchers like Bentzen, taking this opportunity to sequence the species’ genome. Aside from their exceeding rarity, Bentzen says Atlantic whitefish are an archaic species; a relatively unchanged early ancestor of several native fish, offering a window into the past.

Before long (perhaps as early as spring 2020) these whitefish will begin to multiply, an eventuality that could aid Bentzen’s intention to relocate the species, but a costly ordeal in the meantime. While he hasn’t begun this second search for funding, the realities of reproduction are foremost on his mind.

Aquatron is above all else a research facility; these whitefish won’t exceed its capacity for some time, but more hatcheries will be needed to handle a full scale captive breeding project. The dozens of infant whitefish Andrew Breen captured last May were likewise transported to Bentzen at Aquatron, a standing order from DFO.

“We’re the new home for these fish,” says Bentzen. “We’re going to hang onto them as long as is needed, whatever that turns out to be. These fish are part of our natural legacy…that can’t be emphasized enough. There is nowhere else on the planet you can find these fish.”

Do NOT follow this link or you will be banned from the site!