It is not just minimum sizes that have fundamental flaws. Catch limits and maximum sizes undermine the resilience of a fishery. That is, they increase the risk of fishery collapse. The greatest barrier to effective fisheries management is the enourmous difficulty involved in monitoring the state of the fishery. You cannot easily count how many fish you have left or measure their size distribution. This simple problem is the main cause of the collapse of fisheries. Not only can stocks not be monitored, but recreational catches are a highly variable unknown. Furthermore, fish stocks vary from year to year, due to fishing pressure, rain, water tempreature, disease, the annual spwning cycle etc. These changes cascade up and down the food chain.

It's not that difficult to monitor the fishery. Fisheries managers have trigger points for action based on catch rates, average sizes etc and they are getting better at it. A lot of fisheries collapses are due to the fact that they were not listened to or there are juristicional problems (ie tragety of the commons) which meant it was hard to enforce fisheries restrictions. FD ascribes magical properties to marine parks as paints them as a cure to both underfishing and overfishing as well as the saviuor of biodiverstity. He also provides no references for his musings. As Parrish, Hiborn, Buxton and Kearney (to name a few) have pointed out, marine parks have their own problems and at least in the Australian situation are likely to out way any benefits.

Catch limits and maximum sizes contribute to the instability of fish stocks. This is because they provide good protection while stocks are high, but less protection when stocks are low. For example, if the total allowable catch from a commercial fishery is far less than the annual growth of a stock, then the stock will be safe. But if disease, drought or some other problem causes the stock level to fall, then remaining within the total allowable catch will no longer prevent overharvest. Similarly, maximum sizes create instability over longer time periods. While larger fish are still around, they will be protected to some extent, but if they die due to disease, natural mortality, hooking mortality etc, and few smaller fish make it to the maximum size before being caught, then what was once a safely manageed stock can suddenly be put at risk, after a long period of time of apparently stable catches.

Marine parks overcome this instability. They do not become ineffective like catch limits do when stock levels drop for some unpredictable reason. This benefits fishermen, because it reduces the need to set catch limits conservatively to overcome the flaws in traditional management techniques. Marine parks help to reduce the necessity to enforce underfishing as well as reducing the risk of overfishing.

Prof Colin Buxton said that marine parks could accelerated stock collapse in an overfished fishery. Parrish pointed out that if you tried to get the same yield with a network of marine parks you would have to step up dammaging practices such as trawling and actually increase the ecological impact. Prof Bob Kearney pointed out that NSW fish stocks actually show extrordinary resilience to fishing pressure as evdenced by their response to less than ideal fishing practices in the past. The fact is that fishing practices have improved greatly in recent times - so why the rush to declare marine parks?

It's not that difficult to monitor the fishery. Fisheries managers have trigger points for action based on catch rates [/quote]

So not based on fish stocks? How do you measure the catch of recreational fishermen?

I said catch rates sizes and other measures as indicators of fish stocks. I wish you would stop chopping bits out of my quotes and thereby changing the meaning. Regarding rec catches you are just showing you ignorance. They can and are measured using surveys and statisitical techniques.


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It is not magic.

It is when you claim them to be a cure all, have no problems of their own and can't provide any relevant real world examples.

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Which bits do you think need references? [/quote]

Make a start with Australian condition like Buxton and Hilborn have done.

I said catch rates sizes and other measures as indicators of fish stocks. [/quote]

That sounds pretty difficult to me. It's not like counting sheep.

Luckily they don't have you managing our fisheries. They have smart people with degrees in the subject.  

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So they track fish stocks on an anuual basis by measuring recreational catches?

You claimed rec catches are unkown - you have been caught making stuff up.

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Please quote where I said it is magical, or is a cure-all, or have no problems. Or better yet, just stop making stuff up.

Duh, you didn't literally 'say' it is magical what you said can be construed as magical thinking. You fight tooth and nail any sugestion than marine parks have any problems, claim the will prevent overfishing and underfishing, that they are the 'ideal' fisheries management tool. You claim that the will deliver bigger catches and at the same time increase biodiversity. You offer no references to back your claims except overseas studies and a dubious consensus statement. You use these references as 'proof' but show no consideration of the actual fishing pressure and whether traditional techniques are actually working - which is chareletonism. Your sole motivation seems to be to demand marine parks where they don't yet exist.      

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You want me to reference the Australian condition? Please quote the statement I made about the Australian condition that you want me to reference.

Duh, you want to establish marine parks in Australia do you not?

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Luckily they don't have you managing our fisheries. They have smart people with degrees in the subject. [/quote]

I thought you said it isn't that difficult? Are you now saying you need be smart and have a degree to count fish? Perhaps you'd like to explain the assumptions that underpin the statistical methods used? You appear to think that because they have a bunch of academic types doing things with numbers you don't understand, that they must therefor have a firm grasp of the situation, or be able to assess fish stocks reliably. Is that what you think? Perhaps you meant it is not that difficult in the sense that sustained nuclear fusion is difficult, or that terraforming the red planet is difficult. Is that what you meant? Are you trying to contradict my original claim that it is difficult, or is this a subtle way of agreeing with me?

Now your being very silly - it's not that difficult for the people entrusted with managing our fisheries. Certainly professionals like Hilborn, Parrish and Buxton have a better handle on things than you - as shown by this sarcastic rant of yours. What you are saying is that we are so poor at managing our fisheries we must lock away a large portion of it just to make sure. Despite the fact that Australia has already the most regulated and therefore least fished waters in the world.  You then contadict yourself by saying this will increase the yield of the fishery and won't create any significant problem of it's own.

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But they are unknown. Or perhaps you'd like to tell me how many fish recreational fishermen caught last year?

There are survey results available on various state fisheries websites.

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Do you think it is magical?

Yep!

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So you think I have magical thinking? You should get yourself one of those 'magic happens' bumper stickers.

How about 'marine parks - magic happens'.

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I contradict incorrect claims that they are harmful.

Yes and you say you can do this on your own by 'logic' and don't need all those years of pesky study, fieldwork and analysis.

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Yes I do. Do you think that that could only happen by magic?

Pretty much.

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Is that magic?

You can't have it both ways. Not unless the stocks are overfished to start with in which case just about any significant management regime would give a recovery.

Now your being very silly - it's not that difficult for the people entrusted with managing our fisheries. Certainly professionals like Hilborn, Parrish and Buxton have a better handle on things than you - as shown by this sarcastic rant of yours. [/quote]

Speak for yourself PJ. Do you understand the statistical fish counting methods or not? How can you be so certain that these people have a grasp of it when you don't understand it yourself? It is not even their job to manage fisheries. You show more faith in their work than they would ever claim to, apparently based on not understanding what they do.

That just goes to show how little you understand how our fisheries actually are managed. Actually NSW fisheries are managed by input reductions (limiting the ability of fishermen to catch fish), rather than output reductions (a total limit on the catch such as a TAC or quota). So in pointing out the potential problems of the latter, caused by them relying on an estimate of the total stock, all you are doing is supporting the status quo.

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No I'm not. I'm saying that doing so would make us better fisheries managers. Even if we were experts as using the inferior tools there would still be a benefit in using better ones.

We are already using input reductions which are far more equitable and cost effective than marine parks. Ie limits on the no of commercial licenses, gear limits, trip limits, area trawling bans, closed seasons etc. 

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You appear to be drawing an odd conclusion here - that the extent of regulation predicts how heavily waters are fished.

I dont need to predict it - it's an empiricle fact that we have the least fished waters in the world.

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I think I have pointed this out before PJ. There is no contradiction. Improved fisheries management can increase both yield and resilience. You are assuming that there is a fixed relationship between catch and resilience that is unaffected by fisheries management.

That was my point. A lot of the so called evidence for marine parks comes from areas where any change in the management would give a benefit.

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BUt they show the results of surveys. They do not show how many fish recreational fishermen catch.

Duh, the surveys give an estimate of how many they catch.

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No I don't. I correct some of your many errors of logic, and can obviously do so based on logic alone, but that does not mean my entire argument is based on logic. The consensus statement for example is based on observational evidence and acknowledges the inability to predict the net outcome based on logic alone.

It might be obvious to you, coming from your position of ignorance. Are you familiar with the term 'counter - intuative'?

PS you can't keep running back to the consensus statement. You bandy it around as some kind of protectve sheild against any scruitiny. 

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Perhaps you should attempt to understand the mechanisms involved then. Obviously if you think something is impossible, then the evidence won't  make any difference to you. It strikes me as odd that you would revert to evidence and appeals to authorities whose arguments you don't even understand to when all you have to show is that the impossible cannot happen. What makes you so certain anyway?

Well I know I have it all over you on this topic. Your inability to give a logically consistent argument, your lack of knowledge of Australian fisheries and the way they are managed, your resorts to ad hominen attacks, labelling and other propaganda techniques and your phoney appeal to authority consisting of the concensus statement scientists does give me quite a bit of certainty! 

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Yes you can PJ. You appear to think that total catch is the only control mechanism available to fisheries managers, when is is plainly obvious that there are far more refined tools available and that the best use of those tools could improve both total catches and resilience.

See my earlier statements. We are already using a variety of input reductions, so arguing for them over qutas or TAC's is not making much of an argument for marine parks.