A British Columbia fishery scientist says he's worried federal Department of Fisheries and Oceans managers aren't getting an accurate picture of the state of the northern cod stock.

In fact, George Rose's research suggests DFO science may be overestimating the biomass of the stock by 35 per cent.

Those details are contained within a paper — The State of Canada's Iconic Northern Cod: A Second Opinion — recently published by Rose and his University of British Columbia colleague Carl Walters.

"It's basically about the science, not about the management," said Rose.

Rose currently works for UBC's Institute for Oceans and Fisheries and has spent the past 30 years studying northern cod.

More emphasis needed on fishing

Over the past couple of years, Rose and Walters have been reconstructing the stock with data that goes back decades, using a different stock assessment model than is used by DFO scientists.

Rose's main argument in this latest work is that DFO science has consistently not placed enough emphasis on the effect of fishing activity on the struggling stock.

Rose said if the science being delivered to management isn't accurate, managers won't be able to make decisions that best help the stock rebuild.

Under DFO's precautionary approach framework, northern cod has remained in the critical zone since the moratorium in 1992, failing to move into the healthy or even cautious zones for the past 27 years.

Rose said current DFO science points to natural mortality of fish as the main factor in the slow rebound of northern cod, and tagging data may be giving a false sense of the health of the stock.

"We suspect that is leading the model to overestimate what natural mortality is and underestimate fishing mortality. And as a result of that, to overestimate the abundance of the stock by a reasonable amount."

Karen Dwyer says she's comfortable with DFO's findings. (Bruce Tilley/CBC)

Karen Dwyer, DFO's lead biologist working on northern cod, defends the model her team is using and the results.

"I think we are very comfortable with the science that we're seeing. We've talked about impacts of fishing, no impact of fishing," said Dwyer, but she said she's open to other opinions

"I really appreciate that there are people out there challenging our science. That's how science improves."

Dwyer said that unless more information comes forward, DFO will continue evaluating northern cod the same way.

Increased quota set

That's a concern for Rose, who claims the overestimation of abundance is what led DFO managers to announce an increase in the amount of fish harvesters can catch this season in the stewardship fishery.

The quota has been set at 12,350 tonnes, a 30 per cent increase over last season's 9,500 tonnes.

Rose said any increase in fishing activity will mean a setback in northern cod recovery.

"The more we take now, the slower that rebuilding is going to be and we're going to keep our stock below its maximum reproductive potential for a much longer period of time." said Rose.

"That's a decision that has to be made by management and society. That tradeoff has to be made."

Dwyer doesn't disagree; under DFOs precautionary approach, scientists consistently recommend that fishing activity should be kept to its lowest possible level.

"We give the advice that fishing should be kept low, and that's the most that we can say," said Dwyer.

Pick a number … and stick with that for a reasonable period of time, several years. Stop trying to jump around so quickly. - George Rose

But Rose says managers should exercise more caution, and suggests setting a lower fixed quota for a longer period.

"Pick a number — it might be 10,000 tonnes — and stick with that for a reasonable period of time, several years. Stop trying to jump around so quickly, constantly trying to raise it, raise it, raise it … until we get a much better handle on where that stock is really going to go over the next decade."

Both Rose and Dwyer said they're sympathetic to the difficult decisions managers face when it comes to satisfying industry and environmental concerns.

"It's very easy to manage fisheries that are growing and when everything is hunky dory. It's very easy to do that. [But] it's very difficult to manage something like this, where everybody understands that we're still at a relatively low level." said Rose, who is originally from Newfoundland and Labrador.

"I believe that this stock is so important to Newfoundland and Labrador into the long-term prospects for the fishery and that's got to be kept in mind. It's a tough one, there's no question about it."

Ryan Cleary, president of FISH-NL, says DFO should listen to Rose's concerns. (Eddy Kennedy/CBC News)

The president of the FISH-NL union says DFO should take the criticism seriously.

"When one of the pre-eminent fisheries science researchers in the world warns that Fisheries and Oceans may be dramatically overestimating the size of the iconic northern cod stock … you listen," said Ryan Cleary.

Cleary is calling for the cancellation of all fishing for northern cod outside the stewardship fishery, including the recreational food fishery, which is not something the union takes lightly, he said.

"But the long-term viability of the inshore fishery and our rural economy may hang in the balance."

There is currently no measurement of how much fish is taken in the recreational fishery. A tagging program was suggested by the federal government in 2016 but was scrapped after public opposition.

DFO's Dwyer said given the importance of the northern cod stock, some kind of monitoring system of the recreational fishery would be helpful.

"It would be good to get a reasonable estimate of the catch. Of course, it's important. It's a large source of removals. So, we would like to have more information on that."

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