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:


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



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



Quote:


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:


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:


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

Quote:


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

Quote:
 

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

Quote:


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.

Quote:


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.

Quote:


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.

Quote:


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?

Quote:


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.

Quote:


I must have missed that bit.

Quote:


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

Quote:


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

Quote:
 

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

Quote:


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

Quote:


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.

Quote:


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

Quote:


You are looking for the wrong evidence.

Quote:


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

Charles Darwin.

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?

Quote:


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.

Quote:


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

Quote:


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.

Quote:


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.

Quote:
 

Not specifically.

No link. No reference. No surprise.

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