Seals not significantly affecting health of northern cod stocks, says DFO

·5 min read
The latest assessment reveals that northern cod in the 2J3KL region of the south coast of Labrador and northeast coast of Newfoundland remain in the critical zone, and recommends that 'removals from all sources' be kept at the lowest levels possible. (CBC - image credit)
The latest assessment reveals that northern cod in the 2J3KL region of the south coast of Labrador and northeast coast of Newfoundland remain in the critical zone, and recommends that 'removals from all sources' be kept at the lowest levels possible. (CBC - image credit)

A federal scientist says seal predation is not having a significant impact on the groundfish's stalled spawning stock biomass.

Instead, Karen Dwyer, weighing in on the contentious debate over the health of cod stocks, said Thursday that environmental factors and a limited supply of the cod's primary food source — capelin — are more to blame.

"Obviously seals eat cod. However, all of the science that we've looked at so far indicates that the seal predation is not significantly influencing the stock trajectory," Dwyer told reporters during a briefing on the health of cod stocks in an area known as 2J3KL, which includes waters off the south coast of Labrador and northeast coast of Newfoundland.

Dwyer is DFO's lead assessment biologist for northern cod with the Department of Fisheries and Oceans.

The latest assessment reveals that the weight of mature fish — known as the spawning stock biomass — in 2J3KL is estimated at 411,000 tonnes, which places the stock in DFO's critical zone under its precautionary management approach.

That's roughly half the size of the fish's biomass in the 1980s, prior to a collapse of the stock that resulted in a fishing moratorium in 1992, and is the reference point used by DFO scientists when making recommendations on management measures.

The northern cod stocks are found primarily in 2J3KL.
The northern cod stocks are found primarily in 2J3KL.(DFO)

As a result, scientists like Dwyer are recommending that "removals from all sources" be kept at the lowest levels possible.

DFO estimates the spawning stock biomass is roughly the same as it was in 2017, with a 52 to 59 per cent chance that it will grow in 2021.

It's the first stock assessment since DFO released its northern cod rebuilding plan in December, which includes a so-called harvest decision rule that would suggest a quota for the stewardship fishery this year of 13,000 tonnes.

That's slightly higher than the 10,000-plus tonnes fished in 2019 and 2020, but a final decision rests with the federal minister of fisheries.

A larger quota would be welcome news for harvesters eager to increase their landings, but there remains deep disagreement over DFO's approach to managing the cod stocks, and the role played by seals in preventing the stocks from rebuilding.

Trinity Bay fisherman Keith Smith said DFO continues to downplay the impact of seal predation on cod.

"It's like DFO operate in denial of reality," Smith said.

Keith Sullivan, president of the Fish, Food and Allied Workers union, says northern cod quotas should be higher and DFO should change its method of evaluating the stock's health.
Keith Sullivan, president of the Fish, Food and Allied Workers union, says northern cod quotas should be higher and DFO should change its method of evaluating the stock's health.(Todd O'Brien/CBC)

Harvesters have long asserted that the growing seal population is ravaging the cod, and their union agrees.

"Fishing mortality is at an all-time low while natural mortality, likely led by the growing seal population that consumes vast amounts of both capelin and cod, remains high," said Keith Sullivan, president of the Fish, Food & Allied Workers union.

In the late 1970s, said Sullivan, there was a balanced ecosystem because seal populations were controlled through an annual hunt.

"This allowed for a sustainable capelin stock and regrowth of the cod stock even as fishing remained at high levels," he said.

But Dwyer said the natural mortality rate for cod has increased over the past decade, while mortalities through fishing remain very low, as 0.02 per cent.

Dwyer said there have been "big changes" to the ecosystem, with water temperatures on the rise and peak abundance for zooplankton — a vital source of nutrition for cod larvae — not always well timed.

With other food sources such as capelin and shrimp also on the decline, Dwyer said, it "suggests a food limitation problem for the [cod] stock."

But with the debate over seal predation showing no signs of abating, Dwyer said further study is underway to make sure there are no changes in what they've learned already.

Meanwhile, the FFAW is frustrated that fisheries scientists use the average biomass from a five-year period in the 1980s as its limit reference point, or benchmark, for the health of the stock.

The union argues DFO should expand the time frame to determine the health of the stock.

The cod stocks crashed in the 1970s at a time when fishing pressure was high, yet the stocks rebounded, said Sullivan.

If the limit reference point were based on a more historical perspective, "the current stock should be in the cautious zone. Instead, we are only halfway to that point," said Sullivan.

This graph shows how reported landings for northern cod have dropped from a high of some 800,000 tonnes in the mid-1960s, to just over 10,000 tonnes in recent years.
This graph shows how reported landings for northern cod have dropped from a high of some 800,000 tonnes in the mid-1960s, to just over 10,000 tonnes in recent years.(DFO)

If scientists were to take a wider view of the stock to determine management measures, quotas would be higher, Sullivan added.

"Under the current rebuilding plan, the harvest rate for the stock is limited to an extremely low two per cent, making the northern cod stock, which is among the largest in the world, the least harvested cod fishery in the world," he said.

Sullivan said the cod fishery is important to harvesters and processing plant workers, but DFO's report "sends a message to the inshore fishery that government is more concerned with appeasing environmental groups than ensuring families in the fishery can earn a living."

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