A new study by the Fisheries and Marine Institute of Memorial University examining the diets of North Atlantic harp seals found that from 2018 to 2020, harp seals’ consumption rates were 24 times higher than fisheries catch rates in Newfoundland and Labrador for Atlantic cod, Greenland halibut and American plaice.
“Our study shows that harp seals are a major component of cod mortality that should be accounted for in future stock assessments,” said study co-author Dr. Tyler Eddy, adding Fisheries and Oceans Canada stock assessments have long noted a high Northern cod mortality rate that is not due to fishing.
The researchers found that harp seals consume a higher biomass of shared target species than are caught by fisheries and that they have a more significant role than fisheries do on the stalled recovery of groundfish stocks.
With around 4.4 million individuals, North Atlantic harp seals are the second-largest seal population in the world. The animals’ diet shares many of the same species targeted by fisheries, including Atlantic cod and capelin. Harp seals also consume other groundfish, such as Greenland halibut and American plaice.
The study, published in the journal Marine Ecology Progress Series, used various methods, such as analysis of harp seal stomach contents, fatty acids and stable isotopes, to estimate their diets. The data was compared to existing models to analyze consumption at the ecosystem scale to understand predation impact.
While comparison of harp seal diet across research methods showed consistency over time, the frequency of primary prey in their diet fluctuated over time.
“Harp seals are often referred to as indicator species, meaning their diets indicate changes in the ecosystems they prey in,” said Hannah West, a masters of science student in fisheries science and the study’s lead author.
“This data provides insight not only into the impact that harp seals have on fisheries, but can also signify when ecosystems and fish populations are shifting.”
Their findings provide support for including harp seal predation as an ecosystem factor in future fisheries stock assessments in the province.
West said the study provides an estimate of harp seal diets in the province through time, location and season. “Increased understanding of how marine ecosystems work and how populations shift ensures that measures can be put in place to assess and protect the stock of key fisheries species.”
The new study was welcomed by the Fish, Food and Allied Workers Union (FFAW-Unifor) and confirms what Newfoundland and Labrador fish harvesters have been saying for decades: harp seals are having a major impact on groundfish recovery in our waters.
“For years, harvesters have been calling on DFO to acknowledge the obvious — that seal predation is a major barrier to rebuilding fish stocks,” said FFAW-Unifor Secretary-Treasurer Jamie Baker.
“This study validates what’s been seen on the water and reinforces the need for seal population management.”
The Union said it has been consistent in urging DFO to address seal overpopulation and include predation in stock assessments, warning that ignoring this factor undermines both science and sustainability. With harp seal populations exceeding four million, the Union maintains a balanced ecosystem is impossible without management measures.
“Science is finally catching up to what harvesters have been witnessing for years,” said Baker. “If DFO wouldn’t listen to harvesters before, maybe they’ll listen now. Action must be taken to incorporate seal predation into stock assessments — it’s a critical step toward accurate science and responsible ecosystem management.”
It’s also important that government continue to support the marketing of seal products that are sustainable, healthy and responsible.
“A consistent harvest of seals, combined with increased demand and better market access, would certainly help drive effective management of the population as well as create new opportunities in rural and coastal communities,” Baker added.
According to Fisheries and Oceans Canada (DFO), “the biomass of harp seals is currently underexploited, from a fisheries management perspective, allowing ample room for any harvesters wishing to participate in the fishery. Both personal use and commercial seal licenses are available to harvesters,” said Sasha-Gay Lobban, DFO communications advisor.
“The Canadian seal harvest is an important economic and cultural activity in communities in Atlantic Canada, Québec and the Arctic. As such, the department has historically supported marketing efforts for seal products both through the Canadian Fish and Seafood Opportunities Fund (CFSOF), delivered by DFO, and through Atlantic Canada Opportunities Agency (ACOA) funding,” said Lobban.
Lobban said the department recognizes that new research, including from external contributors/academia, such as findings from the Fisheries and Marine Institute, “continues to advance our understanding of the complex relationships among harp seals, cod and other components of the Newfoundland and Labrador marine ecosystem. DFO continues to conduct research to improve its understanding of Canadian seal populations and impacts on fish stocks. DFO’s research indicates that harp seal predation is not the primary driver of the Northern cod stock, but harp seal consumption and its effects on cod remains under investigation. It is well established that Northern cod dynamics are driven by capelin biomass. The department has a dedicated team of scientists who undertake research on seals, including their abundance and diet, to support broader ecosystem and fisheries management objectives.”
Seal assessments take place every five years, said Lobban. “As in previous years, we will continue broad consultations and welcome diverse perspectives before making any management decisions. Stakeholder input, alongside scientific evidence, DFO policies, and socio-economic considerations will inform our responsible path forward to strengthen our fisheries.”
Lobban said the department manages a sustainable, well-regulated and humane seal harvest that supports Canada’s Indigenous, rural, remote and coastal populations. “As with all Canadian fisheries, DFO supports and regulates the seal harvest and is committed to ensuring it is sustainable and conducted safely and humanely.”
