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the effect of management regime on yields (Read 6655 times)
pjb05
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Re: the effect of management regime on yields
Reply #15 - Dec 10th, 2008 at 7:12pm
 
freediver wrote on Dec 10th, 2008 at 2:13pm:
http://www.ffc.org.au/FFC_files/Sustainable_fishing_edu_files/web_pdfs/2_BOFFFF_web.pdf

Why Should we Sometimes Let the Big Ones Go?

BOFFFF theory – Not just for boffins!



Fishers for Conservation (FFC) seems to exist for the promotion of marine parks. It's endorsed by all the usual anti-fishing mafia. It even has a guide how to make a submission in favour of marine parks:

Some hints when writing a submission:

Explain who you are, where you live and what your main interests regarding the Marine Parks Bill are. Eg. “I am a recreational fisher with .. years experience fishing the States’ waters and especially the …. area where I live. I am concerned that the Draft Marine Parks Bill will not provide adequate protection for fish stocks and other marine life from threats such as of unsustainable commercial fishing and mining.”

Outline what you like about the Marine Parks Bill – eg. Point out that you support marine conservation initiatives and understand that spatial management of the marine environment is one of the measures needed as part of ecologically based management of the marine environment to ensure biodiversity conservation and the opportunity for fishing for future generations. Make recommendations regarding what can be done to improve the Draft Bill (refer to the FFC recommendations below for some ideas – don’t forget to mention Recreation Zones).
State that you would like to be kept up to date on future developments regarding Marine Parks and marine conservation.

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freediver
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Re: the effect of management regime on yields
Reply #16 - Dec 10th, 2008 at 9:22pm
 
Quote:
You can't just harping on about the so called consensus statement.


Hence all the other stuff.

Quote:
It's akin to asking us to accept these closures on faith alone.


A scientific consensus statement is pretty much the opposuite of that.

Quote:
Once again these are your own unsubstantiated musings.


So you don't see the problem with killing of the fastest growing specimens and keeping the runts as breeders? Most people don't seem to have any trounble understanding that one. Do you need proof that it is a bad thing before taking it seriously? It isn't just me and my musings either. It is a well recognised problem. Hence the evidence I posted in support.

Quote:
You counterpoint the merits of catch and release by claiming high mortality.


It also achieves a low harvest rate.

Quote:
Also the largest fish aren't always the best breeders


Are you trying to say that killing the big ones and keeping the runts as breeders is a good idea?

Quote:
it depends on the species


Oh really? I'd love to hear your explanation of this.

Quote:
The smaller breeders are far larger in no in any case.


Is that supposed to make snese?

Quote:
Its also well known that under fishing pressure fish grow faster and the juvenile classes benifit from less competition for food and predation.


What's that got to do with anything?

Quote:
Most fish stocks are have been shown to be able to recover remarkably quickly from overfish.


Some do. Some don't. Regardless of how long it takes it is still a bad thing. What's you're point?

Quote:
In any case if you rely on marine parks you may well end up with depleted fisheries plus a few relatively pristine areas where there is no fishing. The odds are that you really need to tackle problems of overfishing head on.


Marine parks do tackle it head on. They also give more fish outside of the marine park, not just inside.

Quote:
Thats at odds with you assertion that you will get an increased yeild with marine parks in place.


No it isn't. You aren't making any sense.

Quote:
A buffer exists only if you are taking less fish out.


Wrong. It also exists if you manage the stocks better. You can even take more fish.

Quote:
You don't consider that other types of input reductions will do the same job.


They can't do it as well as marine parks, that's all.

Quote:
Totally at odds with actual studies on catch and release.


No it isn't. You just don't understand what it says.

Quote:
It's a claim made by anti-fishing activists


No it isn't. Plenty of pro fishing activists say it. It's got absolutely nothing to do with being anti-fishing. It's about bad management. Everyone is against that. Well, nearly everyone.

Quote:
Fishers for Conservation (FFC) seems to exist for the promotion of marine parks.


Seems pretty sensible to me.
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pjb05
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Re: the effect of management regime on yields
Reply #17 - Dec 11th, 2008 at 2:22pm
 
Quote:
You can't just harping on about the so called consensus statement.


Hence all the other stuff.

You mistake literature and enthusiasm for evidence.

Quote:
It's akin to asking us to accept these closures on faith alone.


A scientific consensus statement is pretty much the opposuite of that.

It's a political device designed to quell debate by saying it's already been decided.

Quote:
Once again these are your own unsubstantiated musings.


So you don't see the problem with killing of the fastest growing specimens and keeping the runts as breeders? Most people don't seem to have any trounble understanding that one. Do you need proof that it is a bad thing before taking it seriously? It isn't just me and my musings either. It is a well recognised problem. Hence the evidence I posted in support.

There are still larger fish around when a fishery is fished a maximum sutainable yield, just less than the virgin population. 'Keeping the runts' is just an emotive statement. What is well recognised is that if you have lots of large fish then the price is a lower yield.  

Quote:
You counterpoint the merits of catch and release by claiming high mortality.


It also achieves a low harvest rate.

That is nonsensical.

Quote:
Also the largest fish aren't always the best breeders


Are you trying to say that killing the big ones and keeping the runts as breeders is a good idea?

Refer to my explanation of poulation dynamics and MSY.

Quote:
it depends on the species


Oh really? I'd love to hear your explanation of this.

Sometimes the largest fish aren't always the most fecund. Depends on the biology of the particular species.

Quote:
The smaller breeders are far larger in no in any case.


Is that supposed to make snese?

A larger no of a particular class size can reproduce as much as a smaller no of a larger class size - get it?

Quote:
Its also well known that under fishing pressure fish grow faster and the juvenile classes benifit from less competition for food and predation.


What's that got to do with anything?

If this wasn't the case then there would be no such thing as any substantial fishing effort being sustainable!

Quote:
Most fish stocks are have been shown to be able to recover remarkably quickly from overfish.


Some do. Some don't. Regardless of how long it takes it is still a bad thing. What's you're point?

If you bothered reading your own cut and pastes one claimed that fish recover slowly or not at all from overfishing. My point counters this claim. Also that the worst case is not that bad.

Quote:
In any case if you rely on marine parks you may well end up with depleted fisheries plus a few relatively pristine areas where there is no fishing. The odds are that you really need to tackle problems of overfishing head on.


Marine parks do tackle it head on. They also give more fish outside of the marine park, not just inside.

No they don't. And you assertion is unproven.  

Quote:
Thats at odds with you assertion that you will get an increased yeild with marine parks in place.


No it isn't. You aren't making any sense.

You are giving 20% or more grounds away. They are lost to fishermen. The spillover (if it happens) is probably not more than 10%. So for a total loss to a green zone you are getting 10% back. This is hardly increasing the overall yield.  

Quote:
A buffer exists only if you are taking less fish out.


Wrong. It also exists if you manage the stocks better. You can even take more fish.

Quote:
You don't consider that other types of input reductions will do the same job.


They can't do it as well as marine parks, that's all.

Quote:
Totally at odds with actual studies on catch and release.


No it isn't. You just don't understand what it says.

90% plus survival rate - whats hard to understand about that?

Quote:
It's a claim made by anti-fishing activists


No it isn't. Plenty of pro fishing activists say it. It's got absolutely nothing to do with being anti-fishing. It's about bad management. Everyone is against that. Well, nearly everyone.

Your talking out of your rear end!

Quote:
Fishers for Conservation (FFC) seems to exist for the promotion of marine parks.


Seems pretty sensible to me. [/quote]

Obviously they are a front group rather than a group of concerned fishermen.
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« Last Edit: Dec 11th, 2008 at 2:29pm by pjb05 »  
 
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freediver
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Re: the effect of management regime on yields
Reply #18 - Dec 11th, 2008 at 2:34pm
 
Quote:
You mistake literature and enthusiasm for evidence.


No I don't. The literature is documentation of the evidence. I cannot post fish here, I can only post the documentation. As for enthusiasm, that is the only thing propping up the anti-MP movement.

Quote:
It's a political device designed to quell debate by saying it's already been decided.


But it takes great care to avoid doing that.

Quote:
'Keeping the runts' is just an emotive statement.


No it isn't. That is what happens. Sure some fast growing ones may occasionally slip through, but the selective pressure for slow growing fish will still be there. It is like you are suggestion that a farmer would do OK if he selected all the runts as breeders for next year and threw in one or two of the reasonable specimens. Do you really think that is a good idea?

Quote:
What is well recognised is that if you have lots of large fish then the price is a lower yield.
 

Again, that makes assumptions about the management regime. Making an assumption is not the same as making an endorsement.

Quote:
That is nonsensical.


So is your whole argument about C&R. It's a red herring.

Quote:
A larger no of a particular class size can reproduce as much as a smaller no of a larger class size - get it?


OK, but that still doesn't make it a good idea. Sure, you will have lots of fish, but they will be slow growing - hence the fishery productivity will go down.

Quote:
Also that the worst case is not that bad.


Not that bad? Are you familiar with the worst cases at all? They are a complete disaster.

Quote:
No they don't. And you assertion is unproven.
 

Yes they do. This is well documented. Marine parks give more fish outside of the marine park, not just inside.

Quote:
You are giving 20% or more grounds away. They are lost to fishermen. The spillover (if it happens) is probably not more than 10%.


You are assuming that, but the evidence points in the other direction. YOu have to look at the actual evidence on this, not just make it up as you go along.

Quote:
90% plus survival rate - whats hard to understand about that?


I get it now. You are confusing hooking survival rates with general survival rates. The claim about released fish not always being recaught as bigger fish has little to do with hooking mortality. Even if survival rates were 100% for hooking injuries, it would still be true.

Quote:
Obviously they are a front group rather than a group of concerned fishermen.


Grin Grin Grin You don't really believe that the anti-MP lobby represents all fishermen do you? Or that it is impossible for a group of recreational fishermen to join together in support of marine parks?
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Re: the effect of management regime on yields
Reply #19 - Dec 11th, 2008 at 8:00pm
 
Round and round and round we go.  Will it ever stop? I don't think so...
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Re: the effect of management regime on yields
Reply #20 - Dec 12th, 2008 at 4:32am
 
RecFisher wrote on Dec 11th, 2008 at 8:00pm:
Round and round and round we go.  Will it ever stop? I don't think so...


When ever Freediver is caught out he runs back to the 'consensus' statement, mindlessly turns an accusation around and throws it straight back or pretends the point was never made and goes off on another tangent.
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Re: the effect of management regime on yields
Reply #21 - Dec 12th, 2008 at 6:23am
 
It takes two to tango though.

I can't get over the amount of time you both spend here going back and forth over the same issue.  It seems pointless to me (what is the oint?), but it's your life I guess.
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Re: the effect of management regime on yields
Reply #22 - Dec 12th, 2008 at 10:28am
 
Quote:
When ever Freediver is caught out he runs back to the 'consensus' statement, mindlessly turns an accusation around and throws it straight back or pretends the point was never made and goes off on another tangent.


I am not caught and I do not retreat to the consensus statement. That is merely a starting point, as these few posts right here in this thread demonstrate:

Quote:
http://www.ozpolitic.com/forum/YaBB.pl?num=1228717032/8#8
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pjb05
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Re: the effect of management regime on yields
Reply #23 - Dec 12th, 2008 at 3:55pm
 
RecFisher wrote on Dec 12th, 2008 at 6:23am:
It takes two to tango though.

I can't get over the amount of time you both spend here going back and forth over the same issue.  It seems pointless to me (what is the oint?), but it's your life I guess.


I don't spend my 'life' here recfisher. And pointless in my mind would be putting a post basically saying 'I don't give a toss'. I prefer to look into issues that affect me on a basis of a bit more than the average person who goes on gut feeling and snippets fom the 6 o clock news.
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Re: the effect of management regime on yields
Reply #24 - Dec 12th, 2008 at 4:01pm
 
freediver wrote on Dec 11th, 2008 at 2:34pm:
[quote]
I get it now. You are confusing hooking survival rates with general survival rates. The claim about released fish not always being recaught as bigger fish has little to do with hooking mortality. Even if survival rates were 100% for hooking injuries, it would still be true.



Your cut and paste doesn't doesn't provide any evidence or even gives a reason as to why the two would be significantly different. Of course released fish don't always make it to being large fish. Predation is extremely high in the marine environment so a lot get eaten (as they would if they had not been caught and released)!
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Re: the effect of management regime on yields
Reply #25 - Dec 12th, 2008 at 4:17pm
 
Quote:
Predation is extremely high in the marine environment so a lot get eaten (as they would if they had not been caught and released)!


So you agree with the original point then, even though I 'posted no evidence'?

In fact this is yet another way that a different management strategy could increase catches (on a weight basis, not just on the number of fish). Of course, compared to both marine parks and traditional techniques this would be even less robust.
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Re: the effect of management regime on yields
Reply #26 - Dec 12th, 2008 at 4:37pm
 
freediver wrote on Dec 12th, 2008 at 4:17pm:
Quote:
Predation is extremely high in the marine environment so a lot get eaten (as they would if they had not been caught and released)!


So you agree with the original point then, even though I 'posted no evidence'?

In fact this is yet another way that a different management strategy could increase catches (on a weight basis, not just on the number of fish). Of course, compared to both marine parks and traditional techniques this would be even less robust.


Are you really that thick FD? How does catch and release (with evidence please) negatively impact on long term suvival (apart from short term hooking and handling mortality).

PS, more small fish survive when the larger fish (predators) are fished dow somewhat.
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Re: the effect of management regime on yields
Reply #27 - Dec 12th, 2008 at 4:40pm
 
My original point had nothing to do with catch and release. You mistakenly assumed that hooking mortality was the mechanism for low recatch rates, but it isn't. At least, it is not the main mechanism. Which is why I referred you back to the original point.
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Re: the effect of management regime on yields
Reply #28 - Dec 12th, 2008 at 4:52pm
 
freediver wrote on Dec 12th, 2008 at 4:40pm:
My original point had nothing to do with catch and release. You mistakenly assumed that hooking mortality was the mechanism for low recatch rates, but it isn't. At least, it is not the main mechanism. Which is why I referred you back to the original point.


Your making absolutely no sense. Do you care to elaborate?
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Re: the effect of management regime on yields
Reply #29 - Dec 12th, 2008 at 5:00pm
 
Management techniques effect MSY. With marine parks, you can get higher catch rates and a more sustainable (secure) catch.

Another way to change MSY is to catch smaller fish. This would allow you to take more fish, on weight basis. Of course, it is riskier than both current practice and marine parks. It would require intensive monitoring of stocks if you wanted to exploit it to increase yields.

Note that the use of marine parks rarely, if ever, involves discarding other management tools. Obviously you could loosen some of them, but it would have to be decided on a species by species basis.
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