No subdivision for old codfish

3Ps cod stock on a downward turn despite improved recruitment

Paul Herridge editor@southerngazette.ca
Published on February 12, 2016

DFO

NAFO Subdivision 3Ps is located along the province’s south coast.

For some reason, codfish off the province’s south coast aren’t living to a ripe old age.

“The obvious question is what’s going on?” said Rick Rideout, a research scientist with the Department of Fisheries and Oceans (DFO).

Rideout was the lead scientist on DFO’s science advisory report for last fall’s 3Ps cod stock assessment.

The number of new fish in 3Ps seems to have improved in recent years, Rideout said Thursday, but the stock’s trajectory has taken a downward turn.

“It’s above the limit reference point, but it’s certainly below the target of where we’d like it to be,” he said. There’s certainly some reason for concern, yeah.”

The 3Ps subdivision covers a sizeable section off the south coast, including both Fortune and Placentia bays.

Every year in the spring, Rideout said DFO completes a survey of the stock area, collecting a vast array of scientific information, including number of fish, condition and feeding information.

“If we have more fish being recruited, what’s happening to the stock to be going down,” he opined. “And the fact is the estimates of mortality for the stock are really quite high right now, as high as we’ve seen in the time series that we’ve monitored.”

Some of it is fishing, Rideout said, clarifying scientists don’t know how much is industry-related because the estimates are for total mortality.

“There are a number of things that we’re seeing within the data we’re collecting,” he said.

“The fish in the last few years have been in very poor nutritional condition, so they’re very thin. Some of the diet information that has been collected shows us that cod in that area are feeding primarily on sand lance and on snow crab, surprisingly. Snow crab is certainly not a good diet for cod. It doesn’t have the lipids that they need for producing eggs and it’s just generally not a good diet.”

Other larger ecosystem changes are going on, as well, Rideout said.

Silver hake has always been in the area but in low numbers. They now rival cod, numbers-wise, he said. In one recent survey, they even outnumbered cod. 

“There are some indications that there are overarching changes happening in the ecosystem and the reality is we’re unsure at this point what the consequence of these changes are for cod,” Rideout said. “But there are a number of reasons to think that the productivity for cod might be influenced by the fish changes that are happening.”

With that in mind, it’s best to be cautious, he said.

“For me as a scientist, that’s the take-home message here,” Rideout said.

“Things don’t look terrible, let’s say, right now in terms of where the stock is within the framework DFO uses to manage. But there are a lot of biological indicators that things are uncertain right now. So there’s definitely reason for caution going forward.”

pherridge@southerngazette.ca