A new study into the state of northern cod stocks off Newfoundland and Labrador reveals a dramatic recovery for a species that became commercially extinct in the 1990s.

But the lead researcher, well-known fisheries scientist George Rose, says it's still far too early to ramp up fishing activity.

cod fishing

The cod fishery was once the economic backbone of Newfoundland and Labrador, as illustrated in this photo from the past. (CBC)

"We don't think that time is now. We need to really let this stock gain traction," Rose said Tuesday, during an interview with CBC News.

The study, called Northern Cod Comeback, was published in the Canadian Journal of Fisheries and Aquatic Sciences Tuesday, and was co-authored by Rose.

The journal describes the rebound as the most significant comeback of any fish stock worldwide, with a biomass that has increased from tens of thousands of tonnes to more than 200,000 tonnes within the last decade.

More than two decades of moratorium

That's encouraging news, following more than two decades of moratorium on northern cod, which was once among the largest cod stocks in the world and was an economic lifeline for Newfoundland and Labrador for hundreds of years.

Northern cod is often regarded an example of decline and mismanagement, having collapsed from a peak biomass of several million tonnes.

It was common for commercial fishermen to harvest between 200,000 and 400,000 tonnes of groundfish every year, but a complex series of factors, including overfishing and environmental changes, decimated the cod.

So what prompted the turnaround?

Rose said there are two factors that he knows for sure.

He said northern cod is a "cold water stock," and warming water temperatures over the last 10-plus years have benefited the species.

He added that the "spectacular" growth in cod coincides with the re-emergence of its key food source, capelin.

Smith Sound cod helped kickstart rebound

And Rose has another theory. He believes the large concentration of spawning cod in Smith Sound, Trinity Bay began to disperse around 2007 and "kickstarted" the rebuilding of cod in the so-called Bonavista corridor.

"Over the last seven or eight years … productivity has increased tremendously," Rose said.

He said it's hard to say whether the growth will continue, noting that things in nature rarely follow a straight line.

"We hope this growth continues, but as of now, we need to just follow this situation closely in order to really know," he said.

Calls for bigger quotas

The research underscores what many fishermen have been saying in recent years, and adds to the growing chorus of voices calling for increased quotas. 

But Rose wants a cautious approach, with the biomass still far below what it was during the commercial heyday of the fishery.

"Without a doubt, maintaining low removals of this stock over the past decades has been essential to recovery," he told the journal.

"While the timing of a full recovery remains uncertain, continued protection from excessive fishing remains essential to achieving that outcome."

cod fish

Cod currently account for a small fraction of the commercial fishery in Newfoundland and Labrador. (CBC)

Rose said it's not too early to start thinking about how a future fishery will be prosecuted, while at the same time exercising "restraint and discipline" so as not to interrupt that he calls "cause for optimism."