Ocean food chains remain elusive

The marine biologist’s cod-food web looks more like the architecture of an acid-tripping spider than a depiction of what cod eat, and get eaten by, on the Scotian Shelf.

Cod eat herring and capelin and sand lance — small eel-like fish that in turn eat cod larvae. Seals eat cod, but they prefer herring and capelin and sand lance. Whales eat everything.

Everything eats everything. And that’s nearly all we know about how the hundreds of species on the Scotian Shelf interact — which is a problem.

“If cod came back, we’d have no idea why, because we don’t know what the interactions are,” Iverson said. We’ve had stock assessments — educated guesses made by scientists on how many of a particular species are out there, based on sample trawls and fishermen’s landings. continued

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