PJ, they seem to be missing the point a lot. The choice of fisheries management tool has nothing to do with whether a species is overfished. Any management strategy can be made to prevent overfishing. The choice depends on which strategy does this more effectively.

Did any of them address the issue of the selective pressures arising from minimum sizes?

Faith-based Fisheries - Ray Hilborn

Science and Nature have published a long string of papers on the decline and collapse of fisheries that have attracted considerable
public attention, and occasionally gaining coverage in the New York Times and the Washington Post. I assert that the peer review process has now totally failed and many of these papers are being published only because the editors and selected reviewers believe in the message, or because of their potential newsworthiness.
As examples, let me choose papers by well-established professionals who have long records of significant work beyond the papers discussed below and I emphasize the problem is with the peer review and editorial editorial system, not the authors of the papers.

Conover and Munch (2002) published a highly cited paper in Science showing experimental evidence that size-selective fishing could induce growth changes in fish stocks and suggested this was a mechanism that could lead to collapse of fish stocks. The article never looked at actual fisheries data to ask if the laboratory selection regime imposed resembled what happens in fisheries, nor did they look at the vast body of fisheries data which shows that fish more commonly grow faster, not slower, when fishing pressure is high.

As with much of the anti marine park bandwagon, Ray's criticism seems to be oblivious to the realities of practicing science. He seems to confuse scinetific research with management advice. Obviously an experimental paper is going to be based on an experiment, not real world observations. This does not in any way detract from it's scientific value. He is essentially creating a strawman argument, by pretending it is reasonable to expect scientific papers to be broad and general rather than targetted and specific. There is plenty of research that is based on real world observations, so it is rather odd that he sought out a paper that wasn;t and criticised it for being something it was never meant to be. This is why I find it so hard to take people like Ray seriously. He throws objectivity out of the window in his blind pursuit of cheap criticism of marine parks. He takes one or two papers as representaive of a vast body of work, then criticises them for not encompassing the entire body of work. It is not science, it is churning out drivel that tells people what they want to hear.

You absolutely full of it FD, talk about the pot calling the kettle black! What you are trying to say is there is such a thing as pure research. I'm sure Ray would say that this worth doing. What he disagrees with is the conclusions being drawn from it for fisheries and their management. The paper itself draws conclusions about the real world situation so your strawman argument is without foundation. His point is that the experiments were designed in such a way as to be without reference to the real world situation. No attempt was made to draw interpretations from fisheries data to see if it supported this theory and a good paper would do this. The problem is also the way this paper has been picked up and widely cited by the pro-marine park bandwagon. Seeing it is so widely cited in this way there is nothing wrong with Ray using it as an example.  You just spent pages using this theory as your only justification for marine parks as a fisheries management tool.


Also, it is quite obvious that if you remove competition then the fish will grow faster. This is not mean that there is no detrimental impact from size selection.

Yes but the trouble with the theory is they can't find any such effect.

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I haven't been able to find anything to back up the claim that maximum biomass for a year class in fish tends to occur around the age of sexual maturity. Also, is this based on the impact of minum sizes on population dynamics?

You mean apart from the paper I just showed you. How hard have you looked?

tallowood wrote on Mar 17^th, 2009 at 7:42am:


Yep, fat lot of good the EPA's green placebo did (ie the Moreton Bay Marine Park). The EPA should stick to contolling pollution and leave fisheries management to the DPI scientists.

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No PJ, I'm saying that any one individual scientific paper is not going to prove anything. They are all just a little piece of the puzzle. Picking one at random and criticising it for not covering everything is absurd.

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No-one is drawing any conclusions from a single paper, except perhaps the anti marine aprk lobby. It is an absurd strawman argument. Ray et al have a rediculous habit of holding up one paper and rpetending that all the marine aprk science hangs off it, so that any shortcoming of the one paper is a shortcoming of the whole scientific community.

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No it wouldn't. Not if that wasn't what the paper was about. That's not how it works PJ.

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Sounds like a strawman to me. Perhaps you should take it up with the people who cite it, if you think they are doing it wrong. It is nothing short of stupid to pretend that the concept of selective pressures applying to fish in the same way it applies to all other living organisms hangs off a single paper.

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The theory yes. But to suggest it somehow hangs off this one paper is absurd. The impact of selective pressure on populations is well known. It has been fundamental to farming for millenia. It's not like we even need to prove the principle all over again for fish before we take the problem seriously.

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But they can. If you would stop pretending that it all hangs off one paper you would see that.

Also, are you familiar with the concept that absence of evidence is not evidence of absence? Are you seriously suggesting that we assume fish are somehow immune to selective pressures until we pass some kind of arbitrary absolute proof standard? This goes back to the absurd double standard you apply. You assume marine aprks are bad, despite all the evidence, and accept nothing less than absolute proof. But for minimum sizes it is the opposite. You throw common sense out the window and assume something that is obviously going to have a detrimental impact is good until you get absolute proof otherwise.

You are sacrificing common sense to cling to your position. You are like the greedy farmer who sends his fattest cattle off to slaughter each year because they get the best price, then argues endlessly with anyone who suggests he does otherwise because they cannot meet his standard of proof. You cannot demand that other people continue doing something that is clearly stupid until they have met whatever arbitrary burden of proof you impose on them. Common sense must come first.

pjb05 wrote on Mar 17^th, 2009 at 7:56am:


So we shouldn't have marine parks because they don't stop oil spills? Is that supposed to sound rational? Perhaps you think we could have averted the oil spill with bag limits and minimum sizes.

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No PJ, I'm saying that any one individual scientific paper is not going to prove anything. They are all just a little piece of the puzzle. Picking one at random and criticising it for not covering everything is absurd.

Ray didn't pick it at random, he picked it because it is so widely cited.

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No-one is drawing any conclusions from a single paper, except perhaps the anti marine aprk lobby. It is an absurd strawman argument. Ray et al have a rediculous habit of holding up one paper and rpetending that all the marine aprk science hangs off it, so that any shortcoming of the one paper is a shortcoming of the whole scientific community.

Well if there better papers around covering fishing and its selective  pressures, where are they? Plus you are forgetting about 'Burdens of Proof', which looked at ALL the marine reserve studies available at the time and pointed to a lack of rigor, lack of empiricle evidence and a move to advocacy.  

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No it wouldn't. Not if that wasn't what the paper was about. That's not how it works PJ.

It's how it's supposed to work. It's the difference between theorising and rigorous science.

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Sounds like a strawman to me. Perhaps you should take it up with the people who cite it, if you think they are doing it wrong. It is nothing short of stupid to pretend that the concept of selective pressures applying to fish in the same way it applies to all other living organisms hangs off a single paper.

Now thats a strawman. No one has said that the 'concept' doesn't apply to fish. What is relevant is the extent and magnitude of such a pressure caused by fishing.

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The theory yes. But to suggest it somehow hangs off this one paper is absurd. The impact of selective pressure on populations is well known. It has been fundamental to farming for millenia. It's not like we even need to prove the principle all over again for fish before we take the problem seriously.

Farming is fundamentally different to fishing. As I said it's the extent and magnitude we should be concerned with.

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But they can. If you would stop pretending that it all hangs off one paper you would see that.

Only in a lab under a very artifical set of conditions.

Also, are you familiar with the concept that absence of evidence is not evidence of absence? Are you seriously suggesting that we assume fish are somehow immune to selective pressures until we pass some kind of arbitrary absolute proof standard? This goes back to the absurd double standard you apply. You assume marine aprks are bad, despite all the evidence, and accept nothing less than absolute proof. But for minimum sizes it is the opposite. You throw common sense out the window and assume something that is obviously going to have a detrimental impact is good until you get absolute proof otherwise.

Are you familar with acoms razor, ie that the simplest explanation is most likely to be correct. If you can't find evidence for something then there's a good chance it doesn't exist!

The rest of this paragraph of yours is a series of strawmans. The more shaky your positions are shown to be the more elaborate your rhetorical devices become. I am not hanging my argument on minimum sizes as you make out and it is not a case of minimum sizes vs marine parks. If minimum sizes are shown to be innefective or harmful then they can be downplayed as a management tool and other methods stepped up. In any case they are already a minor method in light of the other extensive non marine park measures currently in use.

You are sacrificing common sense to cling to your position. You are like the greedy farmer who sends his fattest cattle off to slaughter each year because they get the best price, then argues endlessly with anyone who suggests he does otherwise because they cannot meet his standard of proof. You cannot demand that other people continue doing something that is clearly stupid until they have met whatever arbitrary burden of proof you impose on them. Common sense must come first.

Strawman - I am arguing to harvest the optimal number of larger fish to maintain a sustainable harvest. As to selective pressures and your claims of increased harvest under marine parks - the papers I have put up have suggested that to even maintain the current havest under a reasonably managed fishery you would have to step up the fishing in the areas still open to such an extent to cause ecological damage. So if your policy is adopted then selective pressures caused by fishing could well increase!

pjb05 wrote on Mar 12^th, 2009 at 8:06pm:


I do call by every now and then to see of you two are still carrying on the same circular arguments.  Surprised you aren't dizzy yourselves.  If I saw any value in any of this gibber, I'd probably stick around.  See you in a couple of weeks, page 42 probably...