Turning point for cod?

Let’s talk about cod, because of all it symbolizes culturally and historically — and all that cod may hopefully come to symbolize.
Lately, I’ve thought a lot about the great codfish. I just read Mark Kurlansky’s book “Cod: A biography of the fish that changed the world.” First published in 1997, this book deserved my attention eons ago.

Starting with the Vikings, cod has been fished, cured, eaten and traded for centuries. The Vikings, wrote Kurlansky, “learned to preserve codfish by hanging it in the frosty winter air until it lost four-fifths of its weight and became a durable woodlike plank. They could break off pieces and chew them, eating it like hardtack.”

Hardly my idea of a tasty morsel, but cured cod provided sustenance, and its trade built economies. Rights to access to cod grounds and cod markets led to wars. In 1775, the British crown tried to restrict New England trade to local ports and bar New England fishermen from the Grand Banks. Hardly a popular move — and we all know how that one turned out.

For four centuries, from 1497 to the early 1900s, fishermen pursued cod in roughly the same way, with little innovation. Europeans began using engine power in the 1890s. “By the 1890s, fish stocks were already showing signs of depletion in the North Sea,” wrote Kurlansky, “but the primary reaction was not conservation. Instead North Sea fleets traveled farther to richer grounds off of Iceland.”

By 1918, there was a growing trawler fleet in Boston. Otter trawls caught six times the fish of sail ships. During World War II, three dramatic innovations — high-powered ships, dragging nets and freezing fish — shepherded in a golden age of long-distance net trawling.

Now, we know better that there was a downside to all this innovation. Catches cannot increase indefinitely without a reckoning and stock depletion.

But a lot has happened since the book’s 1997 publication. Is it enough to mark a turnaround? Let’s hope so.

“We’ve seen what I would consider some pretty remarkable improvements in stock status in New England groundfish in 10 years,” said Tom Nies, groundfish fishery analyst for the New England Fishery Management Council. “I don’t want to sugar-coat them. We still have a ways to go. But when you look at the biomass trajectories since 1994 for all of the stocks in the groundfish plan, they’re almost all on an upward trend. Whether that’s the result of good management — that’s what we’d like to believe — or the result of blind luck, because of something in the environment, it’s a pretty dramatic turnaround.”

That’s encouraging.

Yet, there’s one major exception: Georges Bank cod. Despite fishing cuts over the last 16 years or so, the Georges Bank cod is not bouncing back and is at 10 percent of fishery managers’ target. Stock sizes are still quite low and the status is still overfished with overfishing happening, per the last federal stock assessment, conducted in 2007.

So what’s going on with Georges Bank cod?

There are several factors, say federal scientists. One is that the ecosystem in the last 15 years has seen a strong build-up of herring and mackerel, fish that can prey on cod egg and larvae.

Another is that the cod may simply need more time for the age structure of the stock to return to health. In the early 1970s, much of the stock was 15 to 17-year olds. Now, most of the spawning cod are 11 or younger, said Loretta O’Brien, research fishery biologist and lead federal assessment scientist for Georges Bank cod at the National Marine Fisheries Service’s Northeast Fisheries Science Center.

There are two ways in which that hampers the stock: Codfish eggs from repeat spawners tend to be more viable than those from first-time spawners and fewer age classes spawning means a shorter spawning season and less chance of eggs encountering ideal conditions.

“We should experiment in the other direction,” said O’Brien, “and let the age structure expand. You can’t expect two to three age classes to support a stock that grows as old as 20. We need to reduce the fishing mortality so these fish can grow older. We need to get good environmental conditions, a boomer year class, conserve that and steward it through.”

The cod’s environment is quickly changing: the water is warming.

Georges Bank and the Gulf of Maine is the southern edge of the cod’s range.

“If some of the projected changes in temperature occur under different climate scenarios, it could become increasingly difficult for cod on Georges Bank,” said Michael Fogarty, research fishery biologist and leader of the Northeast Fisheries Science Center’s ecosystem assessment program.

The ideal water temperature for spawning cod is 40 to 47 degrees F. In 2009, average sea surface temperatures on Georges Bank were slightly higher than 52 degrees F. The Northeast Shelf Ecosystem is warming, according to the National Oceanic and Atmospheric Administration, but the warming trend is still below water temperatures during the 1940s and 1950s.

None of these factors take fishing off the hook, so to speak. Both scientists say these ecosystem dynamics are even more reason fishing needs to be kept in check so the stock can rebuild.

So what’s the takeaway for seafood buyers? Be on the right side of history.

When Kurlansky or another author writes the next chapter in cod’s history, let’s hope the story will be that this is where the over-exploitation became sustainable use. May history judge these decades as a turning point.

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