PJ puts a lot of faith in fisheries management scientists. So much faith even that when the scientists themselves say that the fisheries management tools are bad for the fishery, he still believes they can overcome all obstacles and use them to defeat the evil of marine parks (even if it means complete bans on catching snapper etc).

From the other thread:

http://www.ozpolitic.com/forum/YaBB.pl?num=1307447292


pjb05 wrote on Jun 8^th, 2011 at 8:13pm:

You don't see farmers killing the big cows and returning the runts to the paddock as breeders for next year, but if you listen to the whingers apparently this sort of thing works just fine for our fish stocks and should be encouraged. Looks like someone else doesn't know the difference between terrestial mammals and fish stocks.

pjb05 wrote on Jun 9^th, 2011 at 5:34pm:

What is the difference? The theory of natural selection only applies to terrestrial mammals? Don't keep playing dumb! There is a huge difference as I have explained.

pjb05 wrote on Jun 13^th, 2011 at 8:21pm:

I must have missed that. Can you link me to where you explained how fish are magically protected from the effect of selective pressures? For a starters there is the fact that fish actually grow faster under fishing pressure. Also there have been some remarkable recoveries when fishing pressure has been wound back eg salmon & kingfish in NSW. Hardly signs of adverse genetic changes.

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For a starters there is the fact that fish actually grow faster under fishing pressure.

PJ, this is completely independent of the use of minimum sizes as a fisheries management tool and does not mean that selecting for the slowest growing fish makes the fish grow faster.


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Also there have been some remarkable recoveries when fishing pressure has been wound back eg salmon & kingfish in NSW. Hardly signs of adverse genetic changes.

Likewise, there have been some remarkable failures to recover. However, they are all failures of fisheries management, right? Or do you set the bar so low that is is a success if they have to close a fishery for a few years, so long as there are no marine parks involved?

Also, the revovery of fish stocks after a collapse is not a sign that there is an absence of genetic changes caused by selecting for the slowest growing fish.

I must have missed that. Can you link me to where you explained how fish are magically protected from the effect of selective pressures?

The magical thinking belongs with you. As I recall I pointed out there is no field evidence for such genetic changes.

For a starters there is the fact that fish actually grow faster under fishing pressure. Also there have been some remarkable recoveries when fishing pressure has been wound back eg salmon & kingfish in NSW. Hardly signs of adverse genetic changes.
[/quote]



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For a starters there is the fact that fish actually grow faster under fishing pressure.

PJ, this is completely independent of the use of minimum sizes as a fisheries management tool and does not mean that selecting for the slowest growing fish makes the fish grow faster.

Do they grow faster under fishing pressure or don't they?


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Also there have been some remarkable recoveries when fishing pressure has been wound back eg salmon & kingfish in NSW. Hardly signs of adverse genetic changes.

Likewise, there have been some remarkable failures to recover.

Such as? Has it been found they were due to genetic changes?

However, they are all failures of fisheries management, right? Or do you set the bar so low that is is a success if they have to close a fishery for a few years, so long as there are no marine parks involved?

These fisheries weren't 'closed' just wound back somewhat. The point is there was no sign of adverse genetic changes impeding their recovery.  

Also, the revovery of fish stocks after a collapse is not a sign that there is an absence of genetic changes caused by selecting for the slowest growing fish.

If there is no observable effect of such adverse genetic changes then don't you think that there is a likelyhood that they don't actually exist?

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Do they grow faster under fishing pressure or don't they?

Sure, but this is not really relevant. Or perhaps you have a magical theory that makes it relevant? If so, please explain.


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Such as? Has it been found they were due to genetic changes?

Do I really need to give examples? Are you claiming to be unaware of fish stocks that have collapsed and not recovered?


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The point is there was no sign of adverse genetic changes impeding their recovery.

 

How do you know this? And how is it relevant? Was there actually evidence of absence, or merely absence of evidence?


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If there is no observable effect of such adverse genetic changes then don't you think that there is a likelyhood that they don't actually exist?

Not at all. For starters, there is already plenty of evidence. Second, absence of evidence is no evidence of absence. It can just mean you aren't looking very hard. Once you actually look, the evidence is there to see.

Some examples:

http://www.conservationmagazine.org/2008/07/point-of-no-return/

Fisheries science has managed to embrace some evolutionary ideas. There is certainly an appreciation of the need for conservation of unique gene pools and of genetic diversity within populations. Nevertheless, David Conover, a professor at the Marine Sciences Research Center at Stony Brook University in New York warns that fishery managers treat variation in size as having “no genetic basis or evolutionary consequences at all.” This is odd because the signs of size change in some important fish stocks are already apparent. For example, in the 1940s, cod in the northeast Arctic had an average size of 95 cm. Today they average only 65 cm. And average size and age of fish at maturation have been decreasing for decades in many commercially exploited fish stocks.

The Diekman paper:

http://www.ozpolitic.com/fish/marine-parks-fisheries-management-tool.html#links

http://www.ffc.org.au/FFC_files/Sustainable_fishing_edu_files/web_pdfs/2_BOFFFF_web.pdf

http://www.rw.ttu.edu/butler/techniques/pdf/Fenberg_Roy_2007.pdf

Google turns up plenty more.

[]
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Do they grow faster under fishing pressure or don't they?

Sure, but this is not really relevant. Or perhaps you have a magical theory that makes it relevant? If so, please explain.

How can you be so obtuse. If they grow faster it makes them more resilient to fishing pressure.


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Such as? Has it been found they were due to genetic changes?

Do I really need to give examples? Are you claiming to be unaware of fish stocks that have collapsed and not recovered?

Yes, unless it is you who wants to be stuck with magical theories. I want you to give reasons why they haven't recovered. There can be a variety of these. It would also be helpful if you quoted Australian examples.


Quote:

The point is there was no sign of adverse genetic changes impeding their recovery.

 

How do you know this? And how is it relevant? Was there actually evidence of absence, or merely absence of evidence?

Because they recovered quickly.


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If there is no observable effect of such adverse genetic changes then don't you think that there is a likelyhood that they don't actually exist?

Not at all. For starters, there is already plenty of evidence. Second, absence of evidence is no evidence of absence. It can just mean you aren't looking very hard. Once you actually look, the evidence is there to see.

So what do you suggest - we dont fish at all? Or are you just going to fall back to your false paradigm of all the past fisheries failures vs magical marine parks?

Some examples:

http://www.conservationmagazine.org/2008/07/point-of-no-return/

Fisheries science has managed to embrace some evolutionary ideas. There is certainly an appreciation of the need for conservation of unique gene pools and of genetic diversity within populations. Nevertheless, David Conover, a professor at the Marine Sciences Research Center at Stony Brook University in New York warns that fishery managers treat variation in size as having “no genetic basis or evolutionary consequences at all.” This is odd because the signs of size change in some important fish stocks are already apparent. For example, in the 1940s, cod in the northeast Arctic had an average size of 95 cm. Today they average only 65 cm. And average size and age of fish at maturation have been decreasing for decades in many commercially exploited fish stocks.

The Diekman paper:

http://www.ozpolitic.com/fish/marine-parks-fisheries-management-tool.html#links

http://www.ffc.org.au/FFC_files/Sustainable_fishing_edu_files/web_pdfs/2_BOFFFF_web.pdf

http://www.rw.ttu.edu/butler/techniques/pdf/Fenberg_Roy_2007.pdf

Google turns up plenty more.

We were talking about kingfish and salmon as I recall. PS: I don't see anything about marine parks there. Or that genetic changes have stopped them recovering. Also changes in sizes are not necessarily genetic, they can occur due to pnenotypic variability (this is a controversial area).  

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How can you be so obtuse. If they grow faster it makes them more resilient to fishing pressure.

More resilient than what? It is merely an expression of existing phenotypic plasticity. Are you arguing that this is due to some kind of genetic change resulting from fishing pressure, or just stating the obvious? Can you explain how it is relevant to the selective pressures arising from minimum sizes? You appear to be arguing that it somehow counteracts or disproves them, but you fail to join the dots and make a coherent argument.


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Yes, unless it is you who wants to be stuck with magical theories. I want you to give reasons why they haven't recovered. There can be a variety of these. It would also be helpful if you quoted Australian examples.

Some researchers (eg Diekman) are looking into the impact on a species ability to recover from collapse. You seem to think this is the primary effect of interest, perhaps because that is what I put in the article, but it is not. It is of greater academic interest because it was not forseen. The primary impact is simply that the fish grow slower. This falls into the 'bleeding obvious' category. It is easy to imagine this (slower growth) actually making the stock more resilient to fishing pressure, but I'll let you ponder the mechanism and implications.


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Because they recovered quickly.

So you are merely arguing absence of evidence in a case where you are looking in the wrong place to begin with? Are you concluding that absence of evidence implies evidence of absence?


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So what do you suggest - we dont fish at all?

No. I thought my suggestions are pretty obvious. After all, I did state them. If minimum sizes have adverse Darwinian effects, the obvious response is to reduce reliance on minimum sizes as a fisheries management tool.


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We were talking about kingfish and salmon as I recall.

I must have missed that bit.


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PS: I don't see anything about marine parks there.

Well done. We can discuss the effectiveness of minimum sizes without turning it into a debate about marine parks.


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Or that genetic changes have stopped them recovering.

Like I said, this is a secondary effect. It obviously has serious implications, but so does the primary effect of reducing growth rates.


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Also changes in sizes are not necessarily genetic, they can occur due to pnenotypic variability (this is a controversial area).

 

What is controversial about it? Do you mean changes in growth rates?

[]
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How can you be so obtuse. If they grow faster it makes them more resilient to fishing pressure.

More resilient than what? It is merely an expression of existing phenotypic plasticity. Are you arguing that this is due to some kind of genetic change resulting from fishing pressure, or just stating the obvious? Can you explain how it is relevant to the selective pressures arising from minimum sizes? You appear to be arguing that it somehow counteracts or disproves them, but you fail to join the dots and make a coherent argument.

It's relevant to your insuation that any increase in traditional fisheries restrictions will lead to further restrictions until we are only allowed to fish one day a year!

PS: are you saying that we shouldn't target adult fish? How plausible is a fishery based on tiddlers?


Quote:

Yes, unless it is you who wants to be stuck with magical theories. I want you to give reasons why they haven't recovered. There can be a variety of these. It would also be helpful if you quoted Australian examples.

Some researchers (eg Diekman) are looking into the impact on a species ability to recover from collapse. You seem to think this is the primary effect of interest, perhaps because that is what I put in the article, but it is not. It is of greater academic interest because it was not forseen. The primary impact is simply that the fish grow slower. This falls into the 'bleeding obvious' category. It is easy to imagine this (slower growth) actually making the stock more resilient to fishing pressure, but I'll let you ponder the mechanism and implications.

Typically they grow faster under fishing pressure.


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Because they recovered quickly.

So you are merely arguing absence of evidence in a case where you are looking in the wrong place to begin with? Are you concluding that absence of evidence implies evidence of absence?

How is looking at the field evidence looking in the wrong place?


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So what do you suggest - we dont fish at all?

No. I thought my suggestions are pretty obvious. After all, I did state them. If minimum sizes have adverse Darwinian effects, the obvious response is to reduce reliance on minimum sizes as a fisheries management tool.

If there are such effects then the key would be reducing the take. And once again whereis the evidence of these adverse effects in our popular species?


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We were talking about kingfish and salmon as I recall.

I must have missed that bit.

You haven't now.

[

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It's relevant to your insuation that any increase in traditional fisheries restrictions will lead to

You are reading something into what I wrote that is not actually there.


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PS: are you saying that we shouldn't target adult fish? How plausible is a fishery based on tiddlers?

It depends on the species. If whiting sell so well it is hard to imagine any other species not selling because of size. We already have maximum sizes on many species and it is hardly the end of the world. In practice it probably wouldn't change all that much.


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Typically they grow faster under fishing pressure.

This is irrelevant to the issue of selective pressure arising from minimum sizes.


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How is looking at the field evidence looking in the wrong place?

You are looking for the wrong evidence.


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If there are such effects then the key would be reducing the take. And once again whereis the evidence of these adverse effects in our popular species?

There are far more direct measures of the effect that are not confounded by myriad other factors.

freediver wrote on Jun 13^th, 2011 at 9:28pm:

PJ puts a lot of faith in fisheries management scientists. So much faith even that when the scientists themselves say that the fisheries management tools are bad for the fishery, he still believes they can overcome all obstacles and use them to defeat the evil of marine parks (even if it means complete bans on catching snapper etc). From the other thread: http://www.ozpolitic.com/forum/YaBB.pl?num=1307447292 pjb05 wrote on Jun 8th, 2011 at 8:13pm:  You don't see farmers killing the big cows and returning the runts to the paddock as breeders for next year, but if you listen to the whingers apparently this sort of thing works just fine for our fish stocks and should be encouraged. Looks like someone else doesn't know the difference between terrestial mammals and fish stocks. pjb05 wrote on Jun 9th, 2011 at 5:34pm: What is the difference? The theory of natural selection only applies to terrestrial mammals? Don't keep playing dumb! There is a huge difference as I have explained. pjb05 wrote on Jun 13th, 2011 at 8:21pm: I must have missed that. Can you link me to where you explained how fish are magically protected from the effect of selective pressures? For a starters there is the fact that fish actually grow faster under fishing pressure. Also there have been some remarkable recoveries when fishing pressure has been wound back eg salmon & kingfish in NSW. Hardly signs of adverse genetic changes. Quote: For a starters there is the fact that fish actually grow faster under fishing pressure. PJ, this is completely independent of the use of minimum sizes as a fisheries management tool and does not mean that selecting for the slowest growing fish makes the fish grow faster. [quote]Also there have been some remarkable recoveries when fishing pressure has been wound back eg salmon & kingfish in NSW. Hardly signs of adverse genetic changes.

Likewise, there have been some remarkable failures to recover. However, they are all failures of fisheries management, right? Or do you set the bar so low that is is a success if they have to close a fishery for a few years, so long as there are no marine parks involved?

Also, the revovery of fish stocks after a collapse is not a sign that there is an absence of genetic changes caused by selecting for the slowest growing fish.[/quote]

So where's the info relating to the heading? Magical? Darwin? Are you crazy? Heat, humidity, flies and mosquitoes. Magic all right. Somehow it puts you on a jet heading south.

Charles Darwin.

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If there are such effects then the key would be reducing the take. And once again whereis the evidence of these adverse effects in our popular species?

There are far more direct measures of the effect that are not confounded by myriad other factors.

That's interesting given you don't seem to have any problem teasing out the effect of minimum sizes from all the other traditional management techniques.

I don't do it personally.

If fish start growing slower and reproducing at a younger age, what would you put it down to?

Do you think it is rational to start with the assumption that fish are somehow immune to selective pressures and we needn't concern ourselves with it until it has been demonstrated enough times to satisfy you?

]I don't do it personally.

You have spent pages making this point.

If fish start growing slower and reproducing at a younger age, what would you put it down to?

Do you think it is rational to start with the assumption that fish are somehow immune to selective pressures and we needn't concern ourselves with it until it has been demonstrated enough times to satisfy you?

Strawman. I am saying it doesn't seem to be a significant factor going on our fisheries experiences. This doesn't involve assumptions. PS: where are you going with this? Are you trying to concoct a justification for a large network of marine parks?  

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You have spent pages making this point.

In some cases it is rather obvious, like in some of the evidence I pasted above. Where it is more subtle, I am happy to leave it to the experts.


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I am saying it doesn't seem to be a significant factor going on our fisheries experiences.

You have not presented any rational argument demonstrating this is anything more than an assumption (and an extremely naive one).


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This doesn't involve assumptions.

Where your arguments do not involve assumptions they are just plain wrong. Half the time you don't even bother to actually make the argument and provide a few observations instead, leaving me to wonder what your assumptions and arguments are. Like when you kept posting that some species recover quickly, as if that alone means something.


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PS: where are you going with this?

I believe I have addressed this before. We should reduce our reliance on minimum sizes where possible. I also hope to undermine the incorporation of this fisheries management regulation into culture and morality and the insidious mythology that goes with it.


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Are you trying to concoct a justification for a large network of marine parks?

 

Not specifically.

Looks like I was on the right track and FD was leading us up the garden path. The authors of a recent study concluded that growth related genetic changes in fished populations are much lower than might be expected from laboratory based experiments and that such human induced genetic changes should not be the main priority for good fisheries management. More can be found in Dr Pepperell's latest column in Modern Fishing.

No link. No reference. No surprise.

Was this 'paper' in fishing monthly magazine? It appears to be stating the obvious.

No link. No reference. No surprise.

FD: no brain, no clue, no argument.

To elaborate; I told you the author and the publication, how can you say there was no reference? Also how can I provide a link when it can only be found in a magazine (there is nothing stopping you going to your local newsagent and looking it up).


Was this 'paper' in fishing monthly magazine?

I just told you it was in a monthly fishing magazine (the article not the scientific paper it quoted).

It appears to be stating the obvious.

So you agree your previous contentionswere overblown?

Quote:

So you agree your previous contentionswere overblown?

No PJ. I have not read the article. Neither have you. All you have read is an article about the article. All I have read is your interpretation of an article about an article. All I can tell from that is that it appears to be stating the obvious. You have a curious habit of reading odd things between the lines and jumping to conclusions.

]
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So you agree your previous contentionswere overblown?

No PJ. I have not read the article. Neither have you. All you have read is an article about the article. All I have read is your interpretation of an article about an article.

I have paraphased it - quite accurately. There is nothing stopping you going to the newsagent and reading it and I can't help the fact that there is no link (I don't really feel like typing out the whole article).  

All I can tell from that is that it appears to be stating the obvious. You have a curious habit of reading odd things between the lines and jumping to conclusions.

In this thread and elsewhere you have made a whole theme about genetic changes related to the so called failure of size limits/ conventional fisheries management - are you now backing away from it?

Why would I go to the trouble of buying a magazine for an article about an article that merely states the obvious?


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In this thread and elsewhere you have made a whole theme about genetic changes related to the so called failure of size limits/ conventional fisheries management - are you now backing away from it?

No PJ. Any effect is going to be stronger in a setting where you deliberately control for it. This is stating the obvious and by itself says nothing at all about the extent in the wild. Sorry for bursting your bubble. Maybe next month you can 'accurately paraphrase' an article about an article that actually means something.

freediver wrote on Oct 16^th, 2011 at 5:05pm:

No PJ. Any effect is going to be stronger in a setting where you deliberately control for it. This is stating the obvious and by itself says nothing at all about the extent in the wild. Sorry for bursting your bubble. Maybe next month you can 'accurately paraphrase' an article about an article that actually means something.

But they are looking at what's going on in the wild. To quote directly:

"The authors of the recent study calculated actual rates of growth related genetic changes in fish populations. They found the changes less than might be expected from laboratory experiments. They concluded while human effects on genetics of fish populations should not be ignored, the priority for good fisheries management sould be to control direct effects of fishing to maximise yields and also to protect marine ecosystems".  

Sounds pretty sensible to me PJ.

Did they give the actual rates?

Do you realise that minimium sizes do not maximise yields either, even without the genetic level effects?

Sounds pretty sensible to me PJ.

Then why have you spent pages whining about minimum sizes and genetic effects?

Did they give the actual rates?

There not quoted in the article.

Do you realise that minimium sizes do not maximise yields either, even without the genetic level effects?

A variety of tools are used.

You are still confused PJ. If you think this article somehow contradicts anything I have said you will need to explain it. All I see is you expecting me to go and buy fishing monthly magazine every time you get a bit overexcited over an article about an article.

]You are still confused PJ. If you think this article somehow contradicts anything I have said you will need to explain it.

Well it does, your just stonewalling or are forgettful. When I made similar remarks you tried to ridicule me - just look at the title of this thread!

All I see is you expecting me to go and buy fishing monthly magazine every time you get a bit overexcited over an article about an article.

You can always have a quick read at the newsagent - or I could email Dr Pepperell and get hold of the paper. If I do that are you just going to go all quiet like on the previous thread?