Eavesdropping on the Private Lives of Cod

Feb 16, 2015

Cod fishing - for research - aboard the Barbara K. Peters of Scituate, MA.
Credit Heather Goldstone / WCAI

If you want to protect New England's most iconic fish and still allow fishermen to catch them, it’s critical to know when and where they reproduce. The trouble is, we don't.

It turns out cod and humans may not be as different as you'd think. Chris McGuire, marine programs director for The Nature Conservancy, says cod spawning (a.k.a. baby-making) behavior is a lot like a night club scene. During the day, things are pretty segregated; females are holed up in rocky outcrops, while males hang out around the edges. But after dark, things heat up. The females venture out and the "singles scene" ensues, as females check out their options and males grunt to attract a mate (cue the Barry White).

This is how cod spend the winter.

Unfortunately, sometimes, this love fest gets interrupted. Fishery scientists think that fishing boats can have the same effect as cops breaking up the party (Can you hear the needle scratching across the Barry White album?), and not just for one night. Once broken up, a spawning aggregation may not reform again that year.

That's a scenario that all involved parties - from fishermen to environmental groups, and everyone in between - would like to avoid. Fishermen, in particular, would like to do so without putting huge swaths of ocean off-limits to fishing for extended periods of time. But targeted closures require high-resolution information that has been largely non-existent.

A few years ago, a group of fishermen from Scituate, Massachusetts (the nearest port to some renowned spawning grounds), approached The Nature Conservancy with the idea of doing some research to shed some light on exactly when and where cod come to spawn. The cooperative research project that grew out of that now involves researchers at The Nature Conservancy, the Northeast Fisheries Science Center, Massachusetts' Division of Marine Fisheries, U. Mass. Dartmouth's School of Marine Science and Technology, and - last, but certainly not least - some of those self same fishermen.

One of those fishermen is Frank Mirarchi, who had a boat, Barbara K. Peters, specially built for the dual purposes of commercial fishing and research. Using the Barbara K. Peters as a platform, researchers are surgically inserting radio transmitters into dozens (hopefully hundreds by the time all is said and done) of cod to track their whereabouts. 

Sofie Van Parijs, who leads the passive acoustics group at the Northeast Fisheries Science Center, says working directly with the fishermen who will be most affected by the research results has been a complete departure for her - a welcome and meaningful one. Others researchers in the group echo that sentiment, and Mirarchi remains positive about the project, but some fishermen aren't totally sold.

Early on, researchers brought out maps and asked long-time fishermen, like Mirarchi, to draw circles around the areas they thought cod were using for spawning. The end goal of the project is to put some scientifically-vetted data behind those circles and, if possible, shrink their size.

Instead, shortly after the start of the project, a new cod assessment showed the Gulf of Maine cod stock in a severely depleted condition and managers responded with large, new seasonal closures to protect them.* According to Chris McGuire, that coincident timing was the source of some confusion and mistrust that nearly spelled the end of the whole project. But Micah Dean, who heads up cod spawning research for the Department of Marine Fisheries, says they were able to convince fishermen that the only way to revise the closures is to provide more and better information.

The project has one more year of funding. Dean says the project is ground-breaking but that, realistically, no single three-year project can answer all the questions definitively. That would be a rarity in fisheries - or any other - science.

*Note: This post has been edited. An earlier version stated - incorrectly - that managers had based closures on preliminary data from the cod tagging project.