This issue came up in the marine park thread:

http://www.ozpolitic.com/forum/YaBB.pl?num=1192441509/210#210

PJ insisted that current catch rates could not be improved upon. He based this assumption on the fact that people had calculated a maximum sustainable yield (MSY) based on the stock levels as a percentage of unfished (virgin) stock levels. This obviously assumes a certain management regime, but PJ confused that assumption for endorsement of current management regimes. PJ went on to insist that it is therefor not possible to increase both stock levels and catch rates. That is, it is not possible to go above the catch rate corresponding to the current estimate of MSY without causing stocks to collapse - even if you change management regime. This also carries an implicit assumption that the only way to permanently increase stock numbers is to permanently reduce catch rates. Basically it is the old argument - "this is how it has always been done, therefor there is not a better way" - even though current management regimes have only been in place for a few decades.

Take cattle farming as an analogy. Compared to ranching or hunting wild stock, cattle farmers micromanage the land so that it has a far higher stocking rate. They also manage to get a far higher harvest rate than you could get from harvesting wild stock.

Fisheries have only recently come out of the management regime of unregulated harvest of wild stock. The obvious first step was regulated harvest of wild stock. Obviously there are practical issues preventing the sort of micromanagement you can achieve on land. However, the same principle applies - it is not difficult to increase both stocking rates and MSY. The current estimates of MSY assume the management regime is fixed. They are not an endorsement of the current management regime.

Back  to the cattle analogy. The current management regime is similar to harvesting wild, unmanaged stock, but limiting the amount that can be taken in various ways, one of which encourages the harvest of the best (fattest, fastest growing etc) cattle and leaving the runts to breed for next year. Marine parks are analogous to introducing limited protection of the key breeding stocks and providing some areas where stocking rates can reach higher levels. It is similar to having a stocking rate of far less than the natural levels - that is, stocking rate is not limited by the risk of overstocking (as we are familiar with the issue on land), but by the inability of achieving both high stock levels and high harvest rates under the current management regime.

Marine aprks also make the management regime more stable. Imagine that for some reason it was not possible to count the number of cows you had left. You would have to take an extremely conservative approach to harvesting them, as overharvest is difficult to predict and could have serious consequences for future harvests. If you set aside a few paddocks where cattle are not harvested, and from which cattle could leave as their numbers got too high for the paddock, then you could be a lot more secure in your harvests as you would know that there is always a significant number of cattle in the unharvested paddock.

PJ's argument is equivalent to people switching from unregulated harvest to limited regulation, then deciding a few decades later (and in the face of contradictory evidence) that the limited regulation they initially implimented cannot be improved upon. It is an argument based on ignorance, and an assumption that a certain management regime is best, just because it is traditional, even though it's not actually traditional - it has just been accepted already.

Anyway, the analogy obviously breaks down as you get into too much detail. The main point is that maximum sustainable yield (as it is currently estimated) is not a fixed number. It depends on management regime. If you manage the stocks better, you can get higher stock levels, higher yields and a more sustaianble (secure) harvest - one that is less sensitive to your lack of knowledge of the remaining stock levels, and less likely to crash because you kept harvesting while you were unaware that stock levels had plummeted for some reason.

The current estimates of MSY represent the upper limit on what can be taken. In practice, fisheries must harvest well below the MSY due to the risks associated with not knowing with reasoanble accuracy what the remaining stock levels are. Marine parks increase the MSY and allow you to get closer to it in practice, because the management regime introduces an inherent stability. Current management tools make it easy to overharvest in those years where for some reason (eg natural variation) stock levels are unusually low. Marine parks make it much more difficult to overharvest because the breeding stock is far better protected. Under current regimes, only paperwork stands between fishermen and the breeding stock for next year. Fisheries managers are forced to try to limit catches in a scenario where they don't know what the remaining stock levels are and they don't know how many fish a large group of fishermen is taking. They have managed to get it to work, with only a few dramatic failures. While that is commendable, it is no reason to stick with clearly inferior managemen tools.

Thats pure snake oil by FD. The cattle analogy falls down in that farmers as opposed to ranchers increase the primary productivity by growing special pastures or feeding the cattle grain. This is actually analogous to aquaculture.

In another slight of hand he ignores that other input reductions are used such as restricting the number of commercial licences, milder forms of area management, gear limits, trip limits and closed seasons. These serve as a buffer to overfishing and avoid the socio-economic problems of outright bans.

Note he also provides no evidence for his musings and is completley silent on the actual evidence (or lack thereof) for NSW marine parks, despite some being in place for 15 years.

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Your cattle analogy falls down in that farmers as opposed to ranchers increase the primary productivity by growing special pastures or feeding the cattle grain.

They do that as well. But it doesn't mean they don't manage stocking rates. Obviously the analogy fails in that marine parks will not get you stocking rates above what is natural, but that doesn't mean you can't get both higher stocking rates than current ones and higher catch rates. That is exactly what marine parks do give you. Your assumption that this is somehow impossible is totally baseless.


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In another slight of hand he ignores that other input reductions are used such as restricting the number of commercial licences

This happened on the GBR, but that just demonstrates that the effects you see in that aprticular case are not down to NTZs alone. This is not usually the case.

I suppose you have some actual evidence for an increased total yield resulting from 20% of grounds being off limits to fishermen?

That's what the statement of consensus is all about. There is an enourmous body of evidence backing it up.

freediver wrote on Dec 10^th, 2008 at 11:37am:

That's what the statement of consensus is all about. There is an enourmous body of evidence backing it up.

Then it shouldn't be hard to show some should it?

Showing some would only make a point if someone was claiming there is none. Rather, the anti-MP lobby prefer to say the evidence that is out there doesn't count because it isn't from Australia, or it isn't from NSW, or it isn't from Sydney, or it isn't from Bondi. That is, they will only accept a specific marine park after it has been proven that it will benefit them, but will not accept any proof that doesn't involve the implementation of the specific marine park.

freediver wrote on Dec 10^th, 2008 at 1:36pm:

Showing some would only make a point if someone was claiming there is none. Rather, the anti-MP lobby prefer to say the evidence that is out there doesn't count because it isn't from Australia, or it isn't from NSW, or it isn't from Sydney, or it isn't from Bondi. That is, they will only accept a specific marine park after it has been proven that it will benefit them, but will not accept any proof that doesn't involve the implementation of the specific marine park.

Why don't you provide some evidence instead of trying to pre-empt my possible argument. You have made some starltling claims about marine parks being the ideal fisheries management tool - even that they will increase the MSY beyond what can be achieved by other methods. Why should we accept this if you can't back them up?  

The statement of scientific consensus backs them up. I also posted a reference to a book chapter a while back that was a good introduction to the evidence in favour of marine parks. I'll try to track that down for you.

There are two other interesting links here:

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

http://www.ozpolitic.com/fish/marine-parks-fisheries-management-tool.html#problem-with-size-limits

Size limits also have major problems. Undersize fish frequently die after being returned to the water. More significantly, a minimum size creates selective pressure for fish that grow slower, start breeding younger and put more effort into breeding each year than is optimal. In a natural setting, the most successful breeders tend to be the large fish, and it is the fish that quickly grow large that you want to breed, not the runts. Using minimum sizes is similar to a farmer selecting the runts and small unhealthy cattle each year to be the breeding stock for next year, while selling the prize specimens to the meatworks. This problem is suspected to have contributed to the collapse of many previously productive fisheries, and their inability to recover as quickly as would be expected. Not only are there few fish around, but those fish that remain are runts and pursue breeding strategies that are far from ideal for the quick recovery of stocks. Recent research by Heino and Dieckmann suggests that fish respond quickly to these selective pressures and that only a decade of heavy fishing can introduce serious problems. Unfortunately, the time taken to recover from these problems may be far longer than the time taken to introduce them.

Marine parks overcome all of these problems and provide a 'safety net' to guard against factors that are out of our control. When managing a stock that you cannot see, cannot count and cannot assess on a regular basis such safety nets are essential. Marine parks increase total catches through the 'spillover effect'. This refers to the many ways in which they replenish stocks. Mature fish swim out of the no take zones and get caught. They also provide healthy, fast growing breeding stocks and a consistent supply of larvae.

Note that contrary to popular opinion, it is not true that returned fish always grow bigger and get caught again later. The ocean is a harsh place and most of the returned fish die, even if you ignore 'hooking mortality'. For every kilogram of fish returned for being undersize, far less than 1 kilogram of those same individual fish are caught later in their life. It is the total amount of fish caught that matters and while minimum sizes do help by reducing the total catch, they are far less useful than marine parks as fisheries management tools.

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!

For many years conventional wisdom has told us that
best thing to do to conserve fi sh stocks for the future
is to throw the little ones back and only keep the big
ones. This theory has shaped modern recreational
fi sheries management and lead to minimum size limits
being imposed for most popular species. Scientists are
now beginning to question whether minimum size limits
alone can be effective.

The theory behind minimum size limits and bag
limits is still valid – let as many fi sh as possible reach
maturity before capture (especially for more short
lived species). However this research has opened up
another factor to consider: protecting the BOFFFF.

What does BOFFFF mean?
BOFFFF = Big Old Fat Fecund Female Fish
BOFFFF are the larger, older females which, according
to recent research results, generally produce a lot more
offspring, more times per year, than younger females do.
Additionally, the offspring of larger females are often
healthier and more likely to survive. Older fi sh are more
likely to survive and contribute in the ‘bad years’ when
environmental factors mean reduced recruitment to the fi sh
stocks. For many species, one of the best ways to ensure long
term successful reproduction and replenishment of the fi sh
stocks is to protect the larger, healthy female breeders.

Minimum size limits and evolutionary pressure

There is increasing evidence that fi shing may alter fi sh
evolution. Anecdotal evidence indicates King George
Whiting average size at maturity has actually reduced
over time. This has been linked to the release of smaller
fi sh and the selective fi shing pressure on the larger
individuals. Some fi sh species may actually be getting
smaller on average due to minimum size limit fi shing!

How can we protect the BOFFFF?

There are two major ways to protect the BOFFFF to
help ensure healthy future generations of fish stocks:

1. Return captured large females to the water alive
and healthy.

2. Avoid the capture of some, or all, of the largest
females.

The first option relies on identifying which large fi sh
are female (this is not always possible) and that the
returned fi sh survive and reproduce in a healthy
manner. The stress of capture and release has been
proven to affect reproduction. The level of impact is
dependant on the species being caught and factors
such as the fi shing method, length of time it takes
to land the fi sh, depth of capture and the level of
care taken when releasing the fi sh (see Info Sheet #1
Conserving Your Catch for more info).

The second option relies on fi shing locations and/or
tackle that exclude the capture of the largest fi sh –
this is a new concept for many fi shers.

Marine Reserves - A Guide to Science, Design and Use
Jack Sobel and Craig Dahlgren
Island Press
http://www.islandpress.org/books/detail.html?SKU=1-55963-841-9

Chapter 11, Global Review: Lessons from around the world, goes through marine parks from around the world, including New
Zealand and Australia, and outlines the benefits in detail.

Chapter 4, What Marine Reserves Can Accomplish, is also interesting.

I got this book through a university library.

Another paper contains a good reference list to many other scientific papers outlining the improvements to fisheries from marine parks:

The effects of marine reserve protection on the trophic relationships of reef fishes on the Great Barrier Reef, NAJ Graham, RD Evans and GR Russ, Environmental conservation, 30 (2): 200-2008, 2003
www.jcu.edu.au/school/mbiolaq/subjects/mb3310/research/Trophic%20effects%20of%20GBR%20marine%20reserves.p df

There was also a special edition of Ecological Applications 13(1): S3-S7
Plugging the hole in the ocean: the emerging science of marine reserves, J Lubchenco, S palumbi, SD Gaines and S Andelman
palumbi.stanford.edu/manuscripts/Lubchenco%20et%20al%202003.pdf

Also: Jackson, JBC et al Historical overfishing and the recent collapse of coastal ecosystems, Science, 2003, 293, 27 July: 629-638
www.mcbi.org/Advancing/Jackson_et_al_2001.pdf

Another good list of references:
Biophysical operating principles, recommended by the scientific steering committee for the representative areas program
http://www.reefed.edu.au/rap/overview/principles/bops.html

I didn't actually find the list online - will have to folloow the links or ask GBRMPA

Scientific Consensus Statement on Marine Reserves and Marine Protected Areas.

http://www.nceas.ucsb.edu/Consensus/

A paper looking at what level of protection would give the most spillover effect (ie highest catch rates). Answer is probably around 20-40%.

http://assets.panda.org/downloads/benefitsbeyondbound2003.pdf

The limitations of minimum sizes as fisheries management tools:

Minimum legal sizes and minimum net hole size for trawlers are creating selective pressure that is harming fish stocks. By greatly reducing the liklihood of fish spawning when they get larger, they are causing fish to grow slower, spawn younger at a smaller size and put more effort into spawning each year, which further reduces growth rate. This means lower yields from fisheries. Until about ten years ago people thought this selective pressure would take a century or so of heavy fishing to have any effect. But it now appears that just a few generations (10 years) is long enough to see a significant effect. Furthermore it is likely that reversing these changes will take a lot longer than causing them, because the 'natural' selective pressure to get fish to return to a more normal growth and spawning rate is far weaker.

http://www.iiasa.ac.at/~dieckman/reprints/DieckmannHeino2004b.pdf (1.6 MB)
http://www.iiasa.ac.at/~dieckman/reprints/HeinoEtal2000.pdf (0.3 MB)
http://www.iiasa.ac.at/~dieckman/reprints/HeinoDieckmann2003.pdf (0.2 MB)
http://www.iiasa.ac.at/Research/EEP/lectures/UlfDieckmann5.pdf (7.5 MB) - powerpoint presentation

Will Aborigines be able to fish in closed zones?

I don't think there is a general rule about that easel. Usually not.

I know they don't need fishing licenses. Or at least last I checked they didn't, or they got them for free, or something?

If they can fish in marine parks, get a few Koori boys together and go have fun catching thumpers!

The statement of scientific consensus backs them up. I also posted a reference to a book chapter a while back that was a good introduction to the evidence in favour of marine parks. I'll try to track that down for you.

You can't just harping on about the so called consensus statement. It's akin to asking us to accept these closures on faith alone.  

There are two other interesting links here:

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

http://www.ozpolitic.com/fish/marine-parks-fisheries-management-tool.html#problem-with-size-limits

Size limits also have major problems. Undersize fish frequently die after being returned to the water. More significantly, a minimum size creates selective pressure for fish that grow slower, start breeding younger and put more effort into breeding each year than is optimal. In a natural setting, the most successful breeders tend to be the large fish, and it is the fish that quickly grow large that you want to breed, not the runts. Using minimum sizes is similar to a farmer selecting the runts and small unhealthy cattle each year to be the breeding stock for next year, while selling the prize specimens to the meatworks.

Once again these are your own unsubstantiated musings.  You counterpoint the merits of catch and release by claiming high mortality. Actual real life studies show high survivial rates (often over 90%). You don't mention that there are slot limits for some species too. Also the largest fish aren't always the best breeders - it depends on the species. The smaller breeders are far larger in no in any case. Its also well known that under fishing pressure fish grow faster and the juvenile classes benifit from less competition for food and predation. In fact fisheries biologists will tell you there is a cost to having lots of large fish - you won't get the same yield.  

This problem is suspected to have contributed to the collapse of many previously productive fisheries, and their inability to recover as quickly as would be expected. Not only are there few fish around, but those fish that remain are runts and pursue breeding strategies that are far from ideal for the quick recovery of stocks. Recent research by Heino and Dieckmann suggests that fish respond quickly to these selective pressures and that only a decade of heavy fishing can introduce serious problems. Unfortunately, the time taken to recover from these problems may be far longer than the time taken to introduce them.

Most fish stocks are have been shown to be able to recover remarkably quickly from overfish. Sometimes as quick as 2 years and usually not longer than 5. Our inshore and estuary fish in NSW are fast growing and appear to have a lot of natural resilence in the face of fishing pressure. 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 overcome all of these problems and provide a 'safety net' to guard against factors that are out of our control. When managing a stock that you cannot see, cannot count and cannot assess on a regular basis such safety nets are essential. Marine parks increase total catches through the 'spillover effect'. This refers to the many ways in which they replenish stocks. Mature fish swim out of the no take zones and get caught. They also provide healthy, fast growing breeding stocks and a consistent supply of larvae.

Thats at odds with you assertion that you will get an increased yeild with marine parks in place. A buffer exists only if you are taking less fish out. You don't consider that other types of input reductions will do the same job.

Note that contrary to popular opinion, it is not true that returned fish always grow bigger and get caught again later. The ocean is a harsh place and most of the returned fish die, even if you ignore 'hooking mortality'. For every kilogram of fish returned for being undersize, far less than 1 kilogram of those same individual fish are caught later in their life. It is the total amount of fish caught that matters and while minimum sizes do help by reducing the total catch, they are far less useful than marine parks as fisheries management tools.

Totally at odds with actual studies on catch and release. It's a claim made by anti-fishing activists who no surprise are a big part of the marine park lobby. They need to counterpoint catch and release to justify their fishing bans.  

freediver wrote on Dec 10^th, 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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You can't just harping on about the so called consensus statement.

Hence all the other stuff.


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

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


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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.


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

It also achieves a low harvest rate.


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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?


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it depends on the species

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


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

Is that supposed to make snese?


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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?


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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?


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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.


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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.


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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.


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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.


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Totally at odds with actual studies on catch and release.

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


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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.


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

Seems pretty sensible to me.

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You can't just harping on about the so called consensus statement.

Hence all the other stuff.

You mistake literature and enthusiasm for evidence.


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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.  


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

It also achieves a low harvest rate.

That is nonsensical.


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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.


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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.


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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?


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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!


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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.


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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.  


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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.  


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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.


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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.


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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?


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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!


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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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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.


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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.


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'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?


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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.


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That is nonsensical.

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


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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.


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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.


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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.


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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.


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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.


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

;D ;D ;D 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?

Round and round and round we go.  Will it ever stop? I don't think so...

RecFisher wrote on Dec 11^th, 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.

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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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:


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http://www.ozpolitic.com/forum/YaBB.pl?num=1228717032/8#8

RecFisher wrote on Dec 12^th, 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.

freediver wrote on Dec 11^th, 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)!

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.

freediver wrote on Dec 12^th, 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.

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.

freediver wrote on Dec 12^th, 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?

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.

freediver wrote on Dec 12^th, 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.

Your cut and paste criticised catch and release on the grounds of poor survivability. At first you tried to defend this unsupported assertion, and now with your last two posts you have gone off on a completely different tangent!  

Quote:

Your cut and paste criticised catch and release on the grounds of poor survivability.

So you keep saying. Please quote it.

freediver wrote on Dec 12^th, 2008 at 5:26pm:

Quote: Your cut and paste criticised catch and release on the grounds of poor survivability. So you keep saying. Please quote it.

To quote:

Note that contrary to popular opinion, it is not true that returned fish always grow bigger and get caught again later. The ocean is a harsh place and most of the returned fish die, even if you ignore 'hooking mortality'. For every kilogram of fish returned for being undersize, far less than 1 kilogram of those same individual fish are caught later in their life. It is the total amount of fish caught that matters and while minimum sizes do help by reducing the total catch, they are far less useful than marine parks as fisheries management tools.

and,

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.

;D

freediver wrote on Dec 12^th, 2008 at 5:36pm:

;D

Care to explain FD?

Perhaps if I had put in bold this is not a criticism of catch and release you would have realised it is not a criticism of catch and release. I went to the effort of pointing out that it is not about C&R but you took that to mean it is, just because I mentioned the topic in pointing out that it wasn't about that.

I started a new thread on C&R for you:

http://www.ozpolitic.com/forum/YaBB.pl?num=1229067306

Yes well C&R often is criticised by marine park campaigners, obviously to justify locking anglers out of fishing grounds. So now I see you point is that not all released fished survive due to natural predation . How this supports the case for marine parks I'm not sure. It's well known that juvenile classes benfit under fishing pressure (less predation and less competition for food).

Finally.

It was one of many criticisms of minimum sizes as a fisheries managment tool. Minimum sizes are probably the worst of the bunch. It's not just that they aren't as effective. They are downright detrimental to catch rates. Yet many fishermen put them first because they are used to them and they seem intuitive. It was intended to break through the 'everything is fine with the current regime' mental block.

None of those criticisms apply to marine parks.