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Is Climate Change Killing Our Fish?
Arctic News ^ | March 15, 2004 | Joseph Quillan

Posted on 03/19/2004 4:42:58 PM PST by tgarr

      IN JULY 1992, the Canadian Government closed the Grand Banks, waters off of Newfoundland, and most of the Gulf of St. Lawrence to groundfishing. By the time this moratorium came into effect populations of goundfish, like sole, mackerel, and cod -- fish that live in the Ocean's bottom layer -- had already suffered a catastrophic decline. Most observers pointed to overfishing and damage to habitat by commercial dragnets, as the primary culprits. But by the end of the moratorium, in 1994, it had become clear that the collapse was more serious than at first thought, and that the declines in fish could not be explained by overfishing alone.

The North Atlantic groundfish industry was not the first to suffer from such sudden and severe declines fish populations. Another notable example is the demise of the Pacific sardine industry centered at Monterey, California, which went from 250,000 tons in 1942 to less than 20,000 tons six years later. The sardine population seemed poised to rebound after canneries were closed -- a catch of 100,000 tons was registered in 1958 -- but before long populations collapsed once more, and have never regained their former levels. Scientists in California searching for clues to help explain the demise now hypothesize that fluxuations in ocean temperature may have played a role. Could a similar explantion be applied to declines in the North Atlantic?


The East Coast Cod Industry

The Pacific sardine industry, even in its heyday, was small compared to the giant North Atlantic fishing industry that drew trawlers from around the world to the shores off New England, Nova Scotia, and Newfoundland. By 1968, draws of Northern Cod (Gadus morhua) taken in the waters off Canada’s east coast stood at 800,000 tons. Less than ten years later, however, sudden declines in fish populations had lowered the yield to below 300,000 tons. And other groundfish, various species of hake, were also showing signs of decline.

Concern led both Canada and the United States to pass legislation in 1976 extending national jurisdictions over living marine resources to 200 nautical miles, and foreign fishing fleets were banned from coastal areas. Without foreign trawlers, the take of Northern Cod quickly dropped to 140,000 tons by 1978.

Elated at having the fishing grounds all to themselves, investments in the Canadian fishing industry began to soar. By the mid 1980s catches had increased to 250,000 tons. It was around that time that inshore fisherman and scientists began to note declines in fish populations.

The Canadian government, although acknowledging the dwindling stocks, put off action until 1992. By then the estimated biomass for Northern Cod was at the lowest level ever recorded -- just 1 percent of the level 35 years earlier. For the first time in 400 years fishing of Northern Cod ceased in Newfoundland, over 40,000 people lost their jobs, communities were devastated, and a billion dollars in federal assistance expended to pad the economic impact.


Fish Populations Continue to Decline

Despite the moratorium, however, populations of groundfish in the Atlantic did not rebound as expected. Much to the chagrin and anger, of tens of thousands who have been put out of work, the two year moratorium first announced by Fisheries and Oceans Minister John Crosbie in 1992, was extended again and again. Now two years have turned to twelve, and still there is no sign that cod stocks are recovering.

Scientists have been frantically searching to explain the decline, but explanations have been difficult to pin down. Depensation -- reduced survival or egg production caused by increased predation or reduced likelihood of finding a mate when spawning populations fall below a critical level -- has been put forward as one possible reason for the failure of fish populations to recover, but some view this an unsatisfactory answer, and it has been a difficult theory to prove.

But a new twist is beginning to emerge in the debate over possible causes linked to the collapse, or for its continued demise. Scientists are beginning to take seriously the consideration that climate and fluctuations in marine ecosystems could be a possible culprit.

Michael Heath, a biologist at the Scottish Fisheries Research Services' Marine Laboratory in Aberdeen, and UK chair of the international project Global Ocean Ecosystem Dynamics (GLOBEC), said at a recent meeting of the Royal Society in London that "marine ecosystems, particularly in the northern Atlantic, are much more vulnerable to natural fluctuations than previously realized."

This statement follows scientists' warnings that global warming could, in effect, "turn off the Gulf Stream," causing temperatures in Northwestern Europe to plummet. And that this could happen rapidly, over the course of decades, rather than centuries as some might have figured. Moreover, scientists from the Woods Hole Oceanographic Institution have describe recent changes in Atlantic as "the largest and most dramatic oceanic change ever measured in the era of modern instruments." -- Giving impetus to the suggestion that we could already be in the midst of such an upheaval.

Changes in ocean temperature and currents have broad implications for fish populations. Variation in salinity, cooling of surface waters caused by melting ice in the Arctic, alterations in circulation patterns, could impact fish populations directly, by changing their immediate surroundings, or indirectly, by causing changes in planktonic rich feeding grounds in areas like the Grand Banks, where warm and cold ocean currents collide over broad sections of continental shelf.

Species may, for example, be poorly adapted deal with even small changes in temperature. Or they may face stiff competition or predation, from invading species. Changes in bottom layer temperature could impact bottom feeding groundfish in many ways not yet understood.


Changes Linked to Environment

Scientists from the Monteray Aquarium, in California, have been wrestling with the problem of depressed sardine populations for many years. One group of researchers began drawing on historical surveys and increasingly detailed geophysical data to piece together a seemingly simple, yet somewhat surprising, theory that the depressed sardine populations were a result of environmental pressure; not overfishing as previously thought. They suggest that cycles between sardine and anchoveta occur in relation to decadal shifts in weather and water patterns in the Pacific Ocean.

Their results, published in the 10 January 2003 issue of Science, show that during periods of warmth sardines predominate, and during cold shifts anchoveta have the advantage. Thus, a complex interplay between nutrients, food supplies, and predation exists that shifts throughout the Pacific Ocean in relation to these cycles -- cycles we have more commonly come to associate with La Niña (characterized by unusually cold ocean temperatures in the equatorial Pacific) and El Niño (characterized by warm temperatures.)

[Continued . . . ]


TOPICS: Business/Economy
KEYWORDS: climatechange; coastalenvironment; codfishindustry; envionment; groundfish
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At first I thought this was just more global warming stuff. But that's not the story. I never could figure why the fish never came back after all this time. This seems to make sense.
1 posted on 03/19/2004 4:42:58 PM PST by tgarr
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To: tgarr
The relative densities of phytoplankton and zooplankton are the key.
2 posted on 03/19/2004 4:51:38 PM PST by Argus (If you favor surrender to terrorism, vote Democrat.)
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To: tgarr
"Is Climate Change Killing Our Fish?"

WHO CARES!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

3 posted on 03/19/2004 4:54:49 PM PST by VaBthang4 (-He who watches over Israel neither slumbers nor sleeps-)
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To: Argus
That could be. But that has never killed the fish along the east coast before. At least not in the last 400 years that anyone can remember. Question is then; what's killing the plankton?
4 posted on 03/19/2004 4:59:55 PM PST by tgarr
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To: VaBthang4
New England fisherman for one. I guess they don't count in your book.
5 posted on 03/19/2004 5:04:45 PM PST by tgarr
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To: tgarr
It's like a bad feedback loop, started by overfishing. With fewer deep water fish to feed on the zooplankton, their population mushrooms. Since the zooplankton feed on the phytoplankton, the population of the latter diminishes with the increase in their specific predators. The phytoplankton in the oceans are the main global agents of photosynthesis, turning carbon dioxide into oxygen. Phytoplankton, not the rainforest, are the real "lungs of the planet". Diminish the phytoplankton population and you get more carbon dioxide left in the atmosphere, which causes the greenhouse effect - i.e., "global warming". This is the actual cause of climate change, and it is affecting the North Atlantic as the article notes. It is the result of human activity, in this case overfishing, but it's not the same as industrial pollution, which has been misidentified as the cause.
6 posted on 03/19/2004 5:06:18 PM PST by Argus (If you favor surrender to terrorism, vote Democrat.)
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To: tgarr
The article gives mulitple and diverse potential reasons for the reduction in fish life.

Mybe...just maybe the title should be"
"Dead Fish Cause Climate Change"....
7 posted on 03/19/2004 5:15:54 PM PST by stylin19a (Is it vietnam yet ?)
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To: Argus
So you're saying then that oxygen levels are key. But why hasn't anyone detected lower oxygen levels in the ocean? Or have they? Do you have any information on this?
8 posted on 03/19/2004 5:17:53 PM PST by tgarr
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To: tgarr
factory fishing ships (not meager boats)...using the latest satellite technology and mega nets....there's a clue about fish decline. Let's all go back to subsistence and only hunt/fish our local area.
9 posted on 03/19/2004 5:22:53 PM PST by pointsal
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To: pointsal
I agree. It was a mistake to let all those big factory ships take all that fish. We should have never let factory ships take fishing away from the small-time fisherman.
10 posted on 03/19/2004 5:29:54 PM PST by tgarr
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To: tgarr
BTW, since nobody else has said so: Welcome to FreeRepublic
11 posted on 03/19/2004 5:34:16 PM PST by Clint Williams
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To: Clint Williams
Thanks
12 posted on 03/19/2004 5:36:35 PM PST by tgarr
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To: tgarr
No, it's not oxygen levels in the ocean, but carbon dioxide levels in the atmosphere, that cause the greenhouse effect. Phytoplankton are found closer to the surface of the ocean, because they use sunlight for photosynthesis.
13 posted on 03/19/2004 6:17:37 PM PST by Argus (If you favor surrender to terrorism, vote Democrat.)
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To: tgarr
Salmon runs in the Pacific Northwest are the highest in several decades, and guess what? No dams have been removed. How could this happen? If dams were the problem, the fish runs would have disappeared decades ago.
14 posted on 03/19/2004 6:39:52 PM PST by connectthedots
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To: Argus
This is a chart from Google:

As you can see, the population worldwide has increased from just about 2B in 1942 to 5.8B today; in order to support an increase of this magnitude an organic source of food must have been sacrificed or multiplied along with it.

While I'm not saying that this pressure accounts for the changes we see now, what I am suggesting is that it is a bit late to start saving string.

15 posted on 03/19/2004 6:40:25 PM PST by Old Professer
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To: Old Professer
Of course Mathias was wrong about population, but not entirely.

We do not know the impact that the amount of people we are creating now is going to have. It does throw things out of whack. Mother nature is fighting back though. Fertility rates are dropping rapidly in the first world. Everything tends to balance itself out.

16 posted on 03/19/2004 6:47:33 PM PST by dogbyte12
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To: tgarr
Aren't they still taking barges from N.Y. out into the ocean a few hundred miles and dumping every bit of vile from N.Y. into the SEA?
And the ocean is having problems? Well DUH.
17 posted on 03/19/2004 6:48:27 PM PST by Joe Boucher (G.W. Bush in 2004)
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To: tgarr
Overfishing is the key. The same thing is happening in Alaska. Modern fishing methods have simply become exceptionally efficient, and in even the best of the fishing grounds, nature is not keeping up with our ability to harvest.

I am certainly no eco-freak. I am on the side of the fisherman. But today's catcher-processor boats are just too effective and there are too many of them.

What is needed is more farm-raising of fish and shellfish, but the eco-freaks are fighting this everywhere it starts up. But just as the demand for meat would not be met by hunting wild game without wiping out whole game populations, the world demand for fish cannot be met anymore by hunting in the wild. We can farm it, just like we did with cattle so many years ago.

My .02

18 posted on 03/19/2004 6:51:21 PM PST by Ramius
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To: tgarr
So you're saying then that oxygen levels are key. But why hasn't anyone detected lower oxygen levels in the ocean? Or have they? Do you have any information on this?

There actually was an article about this poster on FR a few days ago - they have detected a decrease in deep-sea oxygen levels. I did a bit of Googling to check out the premises and learned something new, although I should have figured this out from other sources - cold water holds more dissolved oxygen than warm water, which is the opposite of how dissolution normally works.

19 posted on 03/19/2004 6:51:41 PM PST by dirtboy (Howard, we hardly knew ye. Not that we're complaining, mind you...)
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To: tgarr
The small time fisherman cannot keep up with the demand for fish products. Not without fish becoming more valuable than gold per pound.
20 posted on 03/19/2004 6:54:33 PM PST by Ramius
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