Biologist gives hope to Bras d’Or Lake oyster growers

April 23, 2025

Dr. Rod Beresford, Cape Breton University Photo Credit: Truefaux Films

A Cape Breton University biologist and Research Fellow at the Verschuren Centre Inc. is harnessing the power of genomics and collaborating with local experts, including First Nations communities, to revive oyster growing operations devastated over two decades ago by MSX.

MSX (short for Multinucleated Sphere X) is a disease caused by a microscopic parasite (Haplosporidium nelsoni) that infects oysters.

“I’ve met some of the most amazing, tenacious people, and I think there’s some real life lessons about not giving up,” Dr. Rod Beresford said, in describing the local determination to revive the once healthy oyster industry in the Bras d’Or Lake, Cape Breton Island, N.S.

Dr. Beresford’s focus is on early and better detection of MSX. He is also keen to contribute to a longer-term strategy to defeat the parasite by developing “a better oyster using genomics, so that we find oysters that have traits that let them survive the presence of the parasite,” he said.
Currently, he is experimenting with eDNA technology, inspired by COVID detection techniques, to develop a rapid test that can quickly identify the pathogen’s presence through telltale traces of its DNA in the water MSX inhabits.

The goal is to have rapid MSX detection at the shoreline, rather than in the laboratory. That quicker, more immediate capability would help the industry and its regulators, “make better decisions on where animals can or can’t be moved around, which hopefully will lead to a more successful industry down the road,” he said. An important MSX containment strategy is keeping infected oysters out of MSX-free waters to stop the parasite from spreading.

...you know, Rod included us right from the very beginning, and that’s what reconciliation really is.

- Anita Basque, Potlotek First Nation band councillor

Oysters infected with MSX are harmless to human consumption, but the parasite kills oysters and its recent confirmed presence in New Brunswick and Prince Edward Island, now poses a serious threat to the livelihoods of Maritime oyster producers.

That development has put a spotlight on Dr. Beresford’s work, offering hope to a nervous Maritime industry with an annual aquaculture value of $24 million in New Brunswick, $15 million in Prince Edward Island and $5 million in Nova Scotia, based on 2022 Statistics Canada data.

MSX usually kills oysters at least two years old. Losses due to infection can be as high as 90-95 per cent. July and August, when water temperatures are warmest and salinity high, are optimal months for the parasite’s spread.

As a line of defence, Dr. Beresford says there are “all kinds of advantages for genomics.” Although initially costly, he noted, “the investment is really upfront, but once you have the technology sorted, not only…does it become less expensive as time goes on, but you can then adapt that technology to move, say, from the laboratory to much more of a field-based test.”

The United States has been using genomics for decades, he said, “to build better oysters, stronger oysters, faster growing oysters that are able to cohabitate with this parasite. They may get infected; they may not, but the huge advantage is they no longer die from the parasite at the levels they used to.” Developing an MSX-resistant oyster here, he expects, will be the next big move against MSX in Atlantic Canada.

In the long run, he said, that strategy will be needed to counter many oyster pathogens, previously unknown in Canada’s Atlantic waters, that are now creeping up the eastern seaboard due to changing climate patterns. Another newly confirmed arrival is Perkinsus marinus or dermo disease, which is also lethal to oysters, spreads easily, but poses no risk to human health.

In the meantime, Dr. Beresford, aided by knowledgeable local Mi’kmaq community members and local oyster growers, has been concentrating his MSX research on the Bras d’Or Lake. The Potlotek and Eskasoni First Nations made substantial investments in boats and facilities to support oyster-growing operations in the lake. The goals of providing jobs and a better future for their communities were shattered by a 2002 MSX infection, which forced the business to close.

However, working with indigenous and non-indigenous research colleagues on a multi-year pilot project that involved 12 leaseholders, three of whom were from First Nations, Dr. Beresford recently discovered that by suspending caged oysters in the water column, the mortality of MSX was reduced. The discovery has given new hope that the industry could eventually be re-established.

Advice from those colleagues helped him decide where to place 52 cages: half in suspension and the rest on the lake floor. Their expertise was critical. Dr. Beresford said, “there‘s no point in doing it in the wrong place.” It had to be done where the oysters were once plentiful.” He added “someone like Robin Stuart (who worked with oyster growers across the Bras d’Or Lake for decades) can tell you this area doesn’t freeze anymore, or this area freezes every year, or the salinity is in this range in this area.”

When the pilot study wrapped up, Dr. Beresford said an astonished leaseholder who examined the adult oysters that had grown well in the suspended cages told him, “I never thought I’d see a market-size oyster on my lease ever again.” The response has fueled Dr. Beresford’s ambition to take his study to the next level and trial substantially more cage sites and more oysters per site.

He was also heartened, he said, during a recent presentation to hear Anita Basque, a Potlotek First Nation band councillor, tell the audience: “you know, Rod included us right from the very beginning, and that’s what reconciliation really is.” He said, “that was a really nice moment for me.”

Genome Atlantic is collaborating with Dr. Beresford, along with research, industry, and community partners across Atlantic Canada, to tackle the MSX crisis affecting Maritime oyster growers. By leveraging advanced genomics technologies and local expertise, this partnership aims to develop innovative solutions to protect and restore the region’s oyster industry.

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