Posted on 06/29/2005 2:58:30 AM PDT by Einigkeit_Recht_Freiheit
PORTLAND, Maine — The collapse of cod stocks off Nova Scotia changed the marine ecosystem so dramatically that it may be impossible for cod to recover, according to a study by Canadian scientists that could have ramifications for cod stocks at Georges Bank.
Once the top predator, cod is now a bit player in waters off Nova Scotia. Its population on the Scotian Shelf has plunged 96 percent since the 1850s, according to archaeological evidence and old fishing records. In its absence, the entire marine ecosystem has been transformed, said Ken Frank, who co-authored the report published recently in Science magazine.
"It was always thought that the effects of overfishing were reversible," Frank said. "It's pretty shocking when you stop fishing, the fish don't return."
The research of Frank, Brian Petrie, Jae Choi and William Leggett could have ramifications for Georges Bank cod, which also has been decimated by overfishing.
Frank, who works for Canada's Department of Fisheries and Oceans at the Bedford Institute of Oceanography, says the virtual disappearance of cod and other large species such as haddock, flounder and hake led to what scientists call a "cascade effect."
As the population of large predators declined, the fish they prey on -- herring, shrimp, crab and lobster -- have undergone a population explosion. That means cod, which used to sit on the top of the food chain, has now been replaced by smaller fish, Frank says.
Cod's departure is felt at the bottom of the food chain, where zooplankton and algae are now being depleted at a faster rate because more and more fish are feeding on them, he says. Eventually, the lack of food could bring about a crash in the numbers of fish, he says.
Frank says it's unclear whether cod can make a recovery in this new environment.
A big obstacle, he says, is that cod spend the early parts of their lives at the bottom of the food chain. Cod eggs, larvae and juvenile cod are food for other fish. Because there are fewer adult cod, there are now a larger population of fish to eat the young cod.
"The king of the jungle are typically large as adults and are safe," said Robert Steneck, a University of Maine scientist who has studied the cascading effect in the Gulf of Maine. "With overfishing, we are left with babies, and they are not safe."
Because of cod's decline, lobster populations have exploded to record levels, despite increasing fishing pressure, Steneck says. And lobsters today account for more than 70 percent of the total value of Maine's marine resources.
While that may seem like great news, Steneck says, fishing communities have become dangerously dependent on lobsters. "If anything happens to this one species, we have a disaster on our coast," he said.
First, its a misnomer to say that only 10% of the worlds are charted. What you intend to say is that the exact topography of the oceans floor is not charted. This has zip to do with cod.
Are you saying that there are vast unknown fishing grounds in the world's oceans?
Are you saying that the cod are still out there in the ocean, but living at the bottom of some trench?
The article points out that the North Atlantic has been depleted of cod. I'll stand by analogy as quite appropriate. If the cod were out there, they'd be finding them in their nets.
Yep, lots more rats and paper wasps too. What's your point?
This story comes out in re-written form every year.
Quite simple. Nature abhors a vacumn, and a decline in one species will generally be offset by proliferation of another.
According to the article the usual large predators such as cod have been reduced in numbers, meaning that now man can directly consume the now abundant herring, shrimp, crab and lobster that would have been eaten by the cod. How is this bad? How many pounds of lobster does it take to grow a pound of cod? Personally I enjoy lobster more than cod, and it is more efficient for me to eat the lobster than to let cod feed on it, and then eat the cod.
Likewise with your analogy with elk and buffalo, the ecological niche once dominated by them has now been filled with deer, cows, and people. Personally I enjoy eating venison and beef more than elk and buffalo. I also enjoy the company of my friends more than that of elk and buffalo. Is this bad?
No one is claiming that elk, buffalo, or cod are in danger of extinction. There has just been a shift in the proportional space these species occupy in the environment. I know of no "Divine Law" that holds that the numbers of these species must be maintained at the level they were in 1890AD, 1490AD, or 15,000 BC for that matter.
I see nothing inherently bad in a changing enviroment. Environmental change has been occurring since life began. I also believe that most humans are able to adapt to change, and can learn to get by on shrimp and lobster, or venison and steak when cod and buffalo are not plentiful.
You are correct that I was contesting a point you were not trying to make. The author had intimated that cod have declined and this is bad, and that if for some unknown reason lobster declined, fishermen would be doomed. I was contesting that argument.
In my haste this morning I had misinterpreted your comment as being similar to the authors, it was not. I apologize. Josh
"Cod is dead," Neitze?
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