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You keep missing the point PJ. It is a matter of logic, not flat denial. That is why my simple questions leave you so stumped.

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And to measure that extent, you would have to be able to say what the recovery rate would have been if the harm was present. You cannot. You pulled a number - 10 years - out of your arse. So please explain where you got that from, and why the recovery rate we saw indicates no harm done. You cannot do this, because your argument makes no sense.

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I am not trying to wiggle out of real world observations. I am trying to state, as clearly as possible, that your observations do not back up your argument. They are meaningless. You are misinterpretting them. You are slipping up on some very basic matters of logic. You see, but you don;t understand, which is why you can't explain yourself.

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I need evidence that there is no contradiction? Again PJ, you are not making any sense.

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Again PJ you are missing the point. You claimed they said something about the negative impact of minimum sizes on fishery productivty, but they did not. They avoided the issue altogether. All the real world data in the world won't help you if it is measuring the wrong thing. Evidence, references, etc are not an alternative to thinking for yourself. You still have to figure out what it means. You took an inappropriate generalisation about marine parks and took it to be a specific statement about the impact of minimum sizes - an issue the paper didn't even touch on.

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This is about minimum sizes remember. Whatever you think they observed or said about marine parks, it has nothing to do with minimum sizes and you were just plain wrong to claim they did.

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This is getting rediculous PJ. You are assuming that because they didn't even mention the issue, they took it into account. How naive is that?

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So you did look for it, and that is the best you could come up with - a statement that does not even mention the negative impact of selective pressures on growth rate. Do you honestly think this justifies your claim?

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Please quote him.

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I thought we had cleared this up PJ. Remember what I said about saying something specific, not waffling on about impact, harm, pressure etc?

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No they don't PJ, which is why you are unable to explain how. The only point your 'ten years' example illustrates is that you are unable to come up with the actual time frame. You can only complete your argument by making up numbers.

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So you haven't looked at the work of Dieckman and Heino yet? Would you like me to provide another link?

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I am saying I know better than you, because you can't comprehend the issue.

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No it isn't. I explained it to you. It is a matter of logic, not evidence. You have to be able to udnerstand what the evidence means. That is where your argument fails.

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You seem to have forgotten the topic PJ. Either that, or you never figured out what is in the beginning.

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In other words, you did not quote him. You substituted your own deeply flawed interpretation.

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Like I said, you need to think for yourself. References are meant to back up your argument, not act as a substitute for a logical argument.

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Because they're articles are not about this topic PJ. I have explained why you are wrong plenty of times already.

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No it isn't. Read the thread title if you have forgotten. It's about the negative impact of the selective pressure arising from minimum sizes on a fishery.

Also, you did bring up marine parks here:

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However, the papers do not say the opposite. They do not even touch on this particular problem. You seem to assume that because they are critical of one or two marine parks they can be used to back up any criticism you make of marine parks in general. That does not make sense PJ.

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And what? You want me to go looking for it? That is not how it works PJ.

Catch limits, maximum sizes and resilience

http://www.ozpolitic.com/forum/YaBB.pl?num=1244944049/0

The effect has been empirically measured by these scientists:

'Darwinian Debt' May Explain Why Fish Stocks Don't Recover

http://www.sciencedaily.com/releases/2006/01/060112040047.htm

ScienceDaily (Jan. 12, 2006) — Why does it take so long for fish stocks to recover from over-fishing? This problem has been worrying both scientists and fishery managers who expect stocks to quickly rebound when fishing stops.

Now a research team from Stony Brook University believes they have an answer: continually harvesting the largest and oldest fish (as fishing regulations typically require) alters not only size but also numerous other genetic characteristics that are harmful to the overall population.

As reported in Ecology Letters, the researchers experimentally harvested captive groups of a marine fish named the Atlantic silverside. Removing the largest fish over several generations gradually caused a "Darwinian debt": the fish that remained in these populations became progressively smaller but surprisingly many other traits also changed including fewer and smaller eggs with lower survival and growth.

Even behavioural traits like foraging and feeding rate declined. Collectively these changes hamper population recovery and because they are genetic, they don't immediately go away when fishing ceases. How long it would take to undo the debt is now being studied by the research team.

'Undesirable' Evolution Can Be Reversed In Fish, By Letting The Big Ones Go

http://www.sciencedaily.com/releases/2009/03/090303193950.htm

ScienceDaily (Mar. 4, 2009) —  "Undesirable" evolution in fish – which makes their bodies grow smaller and fishery catches dwindle -- can actually be reversed in a few decades' time by changing our "take-the-biggest-fish" approach to commercial fishing, according to groundbreaking new research published by Stony Brook University scientists.

Intensive harvesting of the largest fish over many decades, while leaving the small fish behind, may have unintentionally genetically reprogrammed many species to grow smaller, said lead author Dr. David O. Conover, Professor and Dean of the Stony Brook University School of Marine and Atmospheric Sciences in Long Island, New York.

Although Charles Darwin showed 150 years ago that evolution equips life forms to be better adapted to prosper in their environment, unnatural evolution caused by man's size-selective fishing is causing fish to be smaller, less fertile, and competitively disadvantaged. This has also been a loss for commercial fishers who seek big fish for their livelihoods, recreational anglers in pursuit of trophy fish, and seafood consumers who desire large portions on their plates.

This study demonstrates for the first time ever that detrimental evolution in fish can be reversed, and pokes a gaping hole in theoretical models suggesting that genetic changes are impossible to "undo." It is the result of 10 years of research largely supported by a generous grant from the Institute for Ocean Conservation Science at Stony Brook University.

"This is good news for fisheries, but it also shows that reversal is a slow process," Dr. Conover said. "Over time, fish can return back to their normal size but the reversal process occurs much more slowly than the changes caused by fishing. So the best strategy is still to avoid harmful evolutionary changes in the first place".

Current fishery management plans are generally based upon assessment methods which do not incorporate long-term evolutionary dynamics. It could take years before evolutionary change is incorporated into such plans, since the concept remains quite controversial among scientists.

"It took scientists a long time to reach a consensus on climate change, and acceptance of this phenomenon might require a long time, too," Dr. Conover said.

Dr. Ellen Pikitch, Executive Director of the Institute for Ocean Conservation Science, said, "We now have proof that the negative ramifications of common fishing practices can linger for decades, leaving future generations to grapple with a legacy of diminished ocean productivity. It is essential that fishing be transformed to minimize its evolutionary and broader ecological consequences." Evolutionary dynamics are a fundamental principle of ecosystem-based fishery management (EBFM), a holistic approach that considers the connectedness of different species and the links between species and environmental influences, rather than managing each species in isolation. Dr. Pikitch was among the earliest proponents of EBFM, and lead author of a seminal 2004 article in Science on the concept.

"We have interfered extensively with the natural course of things, and while it is very encouraging that the harmful effects of size-selective fishing may be reversible, the length of the recovery period is sobering," said Dr. Pikitch, who is also a Professor of Marine Science at Stony Brook University. "Restoration of ocean fisheries requires prompt and widespread adoption of an ecosystem-based approach to fisheries management."