Disappearing Cod

March 12, 2017
By Damond Benningfield
Episode:

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Atlantic cod. Credit: National Oceanic and Atmospheric Administration, FishWatch

Atlantic cod was a mainstay of the New England economy for centuries. Commercial fleets brought in tens of thousands of tons of the tasty fish every year. A carved wooden cod was even placed in the Massachusetts House of Representatives.

But overfishing led to a collapse of the industry in the 1990s. And there’s been little rebound since then, despite stricter limits on annual catches. A recent study says that, in at least one region, that may be the result of warmer waters.

The Gulf of Maine is a region of shallow waters along the coasts of New England and southern Canada. It marks the southern limit of the Atlantic cod, which is found in cool waters on both sides of the Atlantic Ocean, and in the Arctic.

Over the last decade or so, the Gulf of Maine has warmed faster than 99.9 percent of all the world’s oceans. Today, the water temperature is about two degrees higher than the long-term average. And researchers say that could have a big impact on Atlantic cod.

It could be especially bad for juvenile cod. Warmer water causes them to use more energy, so they need more food to survive and grow. Yet the higher temperatures are reducing the numbers of the small organisms that young cod eat. So the cod may be diving deeper to find food. But there are more predators in deeper waters as well — including adult cod, which sometimes eat the juveniles.

Researchers suggest that managers will need to take higher water temperatures into account as they try to help cod rebound in the Gulf of Maine.