Came across this in my daily Science Daily reading- keeping big fish
 

ScienceDaily (Dec. 1, 2008) — Scientists at the University of Toronto analysed Canadian fisheries data to determine the effect of the "keep the large ones" policy that is typical of fisheries. What they found is that the effect of this policy is an unsustainable fishery.
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In fact, the opposite policy (keep the small young ones and throw back the large old ones) would result in a more sustainable fishery. In short -- a big fish in the water is worth two in the net.

Put simply, a fish population will produce more young -- and therefore sustain more fishing -- if it is made up of big, old fish.

The team of scientists, led by Paul Venturelli, a graduate student in the Department of Ecology and Evolutionary Biology, used a simple population model, as well as evaluating data from 25 marine fish species. They also tailored their methods to allow for other possible causes for the results, such as the effect of climate.

Finding ways to replenish fishery stocks and improve management provides both ecological and financial benefits.

The research is published in the Proceedings of the Royal Society B.

the studies show they don't use simple Logic :huh:

just think- Canada paid 10 fisheries scientists about 40 to 60 grand a year for this breakthrough.

Canada protects their fishery.

There are conflicting views on this matter. On the surface it appears that big fish will produce more...well in general that is true but as a fish moves beyond its peak fecundity age its eggs are not as ripe as a younger fish. Most other species have trouble reproducing when they get old. (A 19 year old hottie vs a 75 year old grandma) I know fish reproduce through-out their life but if you have ever opened up a 20#er and a 50#er you will see the color of the eggs in the 50 are indeed different, some look dead. I am not a fish biologist but I would rather bet the biomass future of a species on three 20#ers than one 60#er. As I think 3 20's will produce more than 1 60 and also, If the 60 dies for any reason, you have nothing. If a single 20 dies, you still have 2 more. IMO More is better in this case.

Again I am no expert but I like the idea of protecting everything instead of a subset.

Lastly, Fishery guys have proven they don't know jack%$%$%$%$. If they did we would not have the problems we have now. They have been managing fisheries for decades without results.

GEEEEEEEEEEEZ //

WE HAVE ONLY BEEN SAYING THAT FOR THE LAST 6 YEARS TO LET THE LARGE GO ;
BUT IF THAT,S ALL YA FISH FOR & SO DOES EVERYONE ELSE ;;;;;;;;;;DUH :smash:

I think a more valid point is that if you remove the largest fish from the gene pool and release all the small fish, your removing any fish that may be genetically geared to grow big. While some of the the smaller fish may be wired to be small..

I think this is the rationale behind Maines size limits: 1 fish 20-26" or over 40"
Leaves the MILFs in the gene pool and only removes not yet productive(of which there are many) or the old survivors.
The question of if this affects size by eliminating the Genetically large fish from the gene pool would require a further study.

Need to read link to complete report.

DZ

I've always wondered about this myself, and have done a little homework...

What you're talking about is called senescense- biological aging. It's a common theory used among fishermen to justify keeping large fish. One old cow is not as fertile as two younger females, and therefore it's better to have more 20-30 lb fish in the population, and OK to keep the large ones.

Unfortunately this is comparing fish to people- they aren't. There's surprisingly little research done on striped bass fecundity (the ability to reproduce), which is weird seeing as they're such a valuable and important fish. One study by Richards, Fogarty & Teichberg (Density-dependent Growth and Reproduction of Chesapeake Bay Striped Bass) found that as the total length and weight of striped bass increased, fecundity increased. Monteleone & Houde at UMD also did a study entitled Influence of maternal size on survival and growth of striped bass Morone saxatilis Walbaum eggs and larvae- they found that small females produced small larvae, while large females produce large ones. Additionally, the larvae from large females grew faster than those from the smaller ones. They did note that a significant difference in survival to 25 days post hatch was not noticed.

So what does that mean? Large fish produce more fertile and viable eggs than small fish, and large fish produce larger larvae that grow faster. In a laboratory setting, survival was not influenced by female size... However in the wild the larger you are when born and the faster you grow will have a direct effect on survival (less things can eat you).

So basically, while the research on striped bass is limited, the common understanding among icthyologists is that the larger the fish, the more valuable it is to the population and sustainablility. The growth is fairly linear- a 10kg fish is about half as fecund as a 20kg fish.

So, don't think that the old cows aren't providing as much to the population as the smaller ones- they're providing much more. However I wholly agree that protecting just a subset isn't the answer.

Awhile back I asked a fisheries biochemist I know if there was any thing like menopause in fish :). He let me know that in his experience the age of the fish didn't impact the viability of the eggs. Old fish produce more eggs and they are just as healthy as eggs from younger fish.

That is utter nonsense! Does not work that way…all fish have the ability to grow based on the genes at birth (and the conditions they experience during life)

You are born with certain genetics, and they don't change with age.


That is kind of like saying, if we keep circumcising kids, eventually they will be born circumcised.

Taking big fish out of the population does not affect genetics.



Bronko, I think we need to be more conservative than that and save all of them, not just a selected class of fish. As I said, I think fishery experts have a terrible track record for getting it right, best to err on the side of conservation.
SB should be a Gamefish and cut all the management crap.

I still disagree. have you seen a gigantic kid in high school who looks like he is a senior in college?? I am sure there are fish that grow like that too- and if you kill one of these fish when they are just maturing they will not be able to pass on those genes- however the runt bass who take a long time to grow may have many chances to spawn-

to make this simpler- WHen you remove all of the healty desirable stocks, only the runts will thrive.

This is basic population biology - there are libraries full of this stuff. The bigger fish are older, and have been tested through all the challenges life puts out, and have survived. They are the best of the best, and they are the fish you want breeding. Small, young fish consist of the good and the not so good. Each year weeds out the less fit, so each year's class of fish is more likely to be more fit than the year younger.

For striped bass, and many other fish, the biggest fish are all females, and females are more important than males (sorry guys), so there's extra reason to release them.

That's called inbreeding

Really not utter nonsense. If a fish is big, it has the genetics and behavior traits to get big. The more it reproduces, the more big fish there will potentially be. Targeting big fish selects for a population of smaller fish. Lots of evidence in nature for this.

But the problem with this system is that it drops the effective minimum size to 20" and the overall number of fish taken goes through the roof.

A website like this is frequented mostly by guys that can go out and catch keepers and large on a regular basis - its a slanted sample group. "10% of the fisherman catch 90% of the fish" Most of the guys on this board are in that 10%.

When you significantly drop size limits, that 90% of the general population that is struggling to figuere out how to catch a keeper is now bringing home fish. That's an aweful lot of anglers that are now killing little fish. Maine's numbers clearly reflect this.

I think there's something to that genetic component though. It makes sense that the biggest fish each year class make the next round of big fish.


btw - Must really be winter if this is popping up again.

Up there they value live fish that will draw visitors and their $ to Canada.

Down here we value dead fish and the $ they bring.
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Here is the link: http://www.sciencedaily.com/releases...1130210013.htm

It would be cool to read the original paper.

Are you kidding? Canada raped its own cod fishery. As soon as they got the 200 mile limit and got the soviet and other country's fish factories out of their waters, they set up a program to loan money to build new, much bigger cod trawlers - just like the Soviets had used. As a result, their cod fishery was overfished and destroyed. The Canadian cod fishery off Newfoundland was closed in 1992. And the Newfoundland dory fishermen were put out of business, putting hundreds of villages on welfare. The Canadian cod disaster is a classic example of governments doing the worst possible things to produce temporary jobs. It was really one of the worst environmental disasters since the bison were slaughtered on the American plains.

Good job, Canada.

The only thing Maine numbers reflect is that our Striper fishing has been going downhill since the comercial take south of us has gone out of control. Between that and the rediculous by-catch issue we don't see squat for stripers like we did back in the mid 90's. Thanks again to the greedy.The gauntlet the stripers go through is worse now due to the unchecked by-catch with the netters fishing more at night to avoid the enforsement people who are forbidden from working overtime due to budget cutbacks. we could stop keeping any Stripers and it won't make much difference till the by-catch issue is fixed.One boat kills more in bycatch in a season that the whole sportfishing take in a year. ask anyone you know that used to work on a net boat and the story is the same. More bycatch per haul that keepable catch.HUGE WASTE. Don't have to be a scientist to figure it out.

See DZ's post halfway up. It is a pdf file

Reminds me of how the Chinease government commissioned Yao Ming to be hatched.

More mis-information here than you can shake a stick at. Sandy gets the award for being closest to the truth.

Too many people gain too much by killing large fish for anything to change while there are still large fish to be killed.

It has gotten to the point where killing them just to spite others is half the fun.

:hs:

I just finished watching the documentary..."The end of the line" mainly about tuna but this is a must see.

basically... the rest of the world is raping the oceans and if we keep going at our current rate there will be nothing left in the ocean in 50 years. Europe and Asia need to get some control on their fishery...we look good compared to them.

Your statement isn't very specific. I'd be interested to know what you mean.
As far as "sandy", You mean when he says that they should reduce the pressure on all sizes and make them a game fish?

for me and my viewing dollars~~~

^^^THIS GUY^^^ makes the most sense! and he has the degrees and hours on the sea and in the labs to form his opinions from. as much as i like your vim and vigor, MakoMike, the biological science does support Eb's view.

An interesting note on that point, the 'empty oceans by 2048'- It was a theory put out in 2006 (I think), but was roundly rebuked two years later... But people still cite it as fact. I just read an interesting article on just that, I'll try & remember to post it on Monday.

End of the Line is a good movie though- not wholly accurate, but still good. Like anything, it's best to get your information from both sides and decide what you believe from there, rather than just one source.