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Posts: 7037
Location: Northwest Chicago Burbs | Fish 1 = X
Fish 2 = Y
Lake 1 = Q
Lake 2 = Z
X in Q = 30 inches high end (he)
X in Z = 45+ (he)
Y in Q = 30 (he)
Y in Z = 45 (he)
If X is native to Q, but has a greater HE in Z and the same is the case with fish Y, is it possible the variable that is the deciding factor is the Lake, and not the fish? |
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Location: Rhinelander, WI | I’ll play! Yes absolutely!
However what happens when you have Fish 3 that only grows to 30(HE) in both X and Y? And there is no way to tell a 1,2 or 3 fish apart, when looking at 30 inch sample.
Nail A Pig!
Mike
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| I gave up story problems years ago. Too much thinking and not enough fishing. |
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Location: Nowheresville, MN | At he risk of sounding like a doofus, what's "he"? Were they supposed to be 'he' and 'she'? |
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| he=high end
Looks to me like the lake is the variable with the info given. |
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Posts: 462
Location: Madison Wi. Chain | Need a bigger sample size, but if the bell curve for size remained the same despite the variable fish species, one would want to start looking at other variable such as forage, nutrients in the lake, mortality of fish in each of the lakes. Suddenly a simple problem only leads to more questions. Such as What is the most important variable for growing large fish? My GUESS: It is a combination of genetics and environment. So my answer is G&E! BG |
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Posts: 714
Location: Rhinelander, WI | From a recent email exchange with Madison WDNR personnel:
“Growth and ultimate length are very plastic in fishes, and while there is a genetic component, our data indicate that the size of the lake accounts for 82% of the variability in ultimate length in Wisconsin musky populations.”
That still leaves 18% unknown.
Nail A Pig!
Mike
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Posts: 1764
Location: Ogden, Ut | MRoberts - 4/16/2008 7:32 AM
From a recent email exchange with Madison WDNR personnel:
“Growth and ultimate length are very plastic in fishes, and while there is a genetic component, our data indicate that the size of the lake accounts for 82% of the variability in ultimate length in Wisconsin musky populations.”
That still leaves 18% unknown.
Nail A Pig!
Mike
Not necessarily unknown Mike. Just that ALL of the other variables combined only account for the remaining 18%. Granted, some are unknown, but many are not. Water chemistry, growing season, forage available (both amount and type), cover available, nutrient availability, angling pressure, and yes, even genetics probably all have effects on fish growth and length. Of those, if the genetic component is not obvious (i.e., Shoepacs, for example), it's contribution to the overall length and growth rates of fish is likely pretty minimal.
S. |
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Location: Stevens Point, Wi. | Did you start taking an advanced algebra night class?  |
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| One thing I know for sure: If it goes on the wall before it reaches 40" its genes don't matter all that much.
One thing I I'm pretty certain of: The best genetics will never make up for forage, water chemistry, and a lack of suitable spawning habitat.
One thing I suspect:
If you took all the muskies in WI, and divided them evenly among the following areas: Eagle Lake, Lac Seul, Mille Lacs, Vermillion, Cass, Georgian Bay, Green Bay, and the St Lawrence River; all 8 of those places would still have just as many trophy class fish as they do today.
And if you used all those places as brood stock soruces, stocking all those fish in the lakes throughout WI, you would STILL have a hard time catching anything over 50" in 95% if the WI fisheries.
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Posts: 3479
Location: Elk River, Minnesota | I'm wondering if it could be more than just the lake itself Slamr. Reason: population density. Say for example lake Q has a very high density of fish per acre. Now...given a high density, the lake can only support a certain amount and size of fish. This would create a "stunting" affect since the water can only support so much. More fish would lend to a smaller size structure...and generally less fish means larger size structure. If Lake Q and Lake Z are have similar physical features (habitat, available forage, etc) but different densities, it very well could be density that determines the overall size structure of the lake.
I would tend to think in the grand scheme of things, that the lake (it's size, forage base, available habitat, et.c will be a bigger factor in the overall size structure the lake can support more than genetics or density alone). This particular species usually has a small population (in general), so density may not even be a factor...but...something to consider...
I do feel, though, that there are situations where a certain genetic population may not grow well in any body of water even if the lake has good forage, structure etc. Example: Shoepac strain fish in MN. Now...I don't profess to be any scientist on this, but based upon my 30 years fishing a lake system that used to have shoepac stocked in it and has not received any stocking since then, the fish are generally of a smaller nature than those bodies of water that did not have a diverse enough population....and this is a lake that contains cisco, sucker and perch as primary forage species. There are 50 inch fish to be had, but they come about once every 6 - 8 years or so. Overall, the lengths of fish I have caught on this system (and over those years, it is many....) all range in the mid 30 inch bracket. I have caught only 4 fish over 40 inches with the largest being 44" back in 1997...I have only broken the 40" mark one other time since then...gotten close, but never broke it. To this day, I feel that the introduction of the shoepac strain of fish has added opportunity to the lake to catch more fish, but for size, I feel it has hurt the fishery.
Steve
Edited by VMS 4/17/2008 12:41 PM
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Posts: 462
Location: Madison Wi. Chain | I think VMS brings up a good point. I might ask why population density has any bearing on the size of fish? We all know that for some reason a high population of musky per acre of lake produces smaller fish. The question is why? My guess is that a high population of musky per acre has a strong relationship to one of the environmental factors such as quality of forage available. Hard for me to wrap around the idea that 82% of the variability is environmental. BG |
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| Big Gun, I think it stands to reason. Put a lot of muskies in a lake, and there's less food for each one. Put only a few in there, and there's as much food as they can eat, with no competition for it.
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Location: Elk River, Minnesota | I think it might even go beyond that, though... In past years, I have owned a few aquariums, and, being a limited space it can only support so many fish in it given a relative size. Right now, the number evades me, but a certain amount of water can only hold so much dissolved oxygen, which limits the amount of fish it can support. This also ties into waste break down (ammonia I believe) along with other nutrients. In my thoughts here, I am thinking of a lake as just a large aquarium, where it can only support so many fish of a given size...smaller size, more fish-larger size, less fish. But...forage takes up some of that too...so if you have a bunch of forage but it is not of a preferred species, it too can limit the size structure in the lake...especially if there is an overabundance of them.. Again, no science involved here on my part...just a humble observation as to a possible "why"
Steve
Steve |
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Posts: 462
Location: Madison Wi. Chain | I am not totally sold on the idea that forage is the variable in high population density lakes = smaller fish. I know of several lakes with a high density population of fish that have a ton of forage available, but still do not seem to grow that big. Besides, if a fish is hungry and looking for food, wouldn't it just eat just more smaller prey so as to meet its genetically programmed set point for weight? BG |
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Location: Nowheresville, MN | The size of the available forage is important. You can't grow 30lbrs on 6" perch alone. The energy and time needed to capture 1 large prey item is less than the capture of several smaller items. Small fish tend to live in different habitats than large fish, even of the same species. Large predators can't effectively capture prey in the habitats of these smaller fish.
Edited by tfootstalker 4/18/2008 5:28 PM
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Location: Elk River, Minnesota | big gun - 4/18/2008 7:59 AM
I am not totally sold on the idea that forage is the variable in high population density lakes = smaller fish. I know of several lakes with a high density population of fish that have a ton of forage available, but still do not seem to grow that big.
My point is the water can only sustain a certain amount of fish...and that includes forage. A lake has a limited supply of dissolved oxygen in it and all fish need it to survive. Sure..there might be oodles and oodles of forage, but if the lake is reaching a maximum amount of fish it can support, the predator fish could gorge continuously, and it would not make a difference...the size will continue to be small...
Steve |
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Posts: 462
Location: Madison Wi. Chain | I see your point, the lake can only support an upper limit of total fish population. If your point is true, then the fish being recruited into the lake can only grow until they reach the upper limit of what the water can hold in terms of total fish populations. Interesting arguement. Some of those muskies in that lake could actually be brutes, that just can't grow that big. BG |
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| Well, wait a minute -- if that's true that the lake can support a fixed volume of biomass, then that biomass could be distributed in any number of ways -- lots of forage and only a few predators, lots of predators and not much forage; any combination of size and species of fish could equal that maximum level. If the system held a lot of forage and a few predators, the predators would just eat a lot, reproduce well, and grow to a large size. Overall the volume of fish wouldn't change, only the distribution would change.
If there are too many predators and not enough prey to go around, eventually the predatory species population will crash, either through die offs or unsucessful reproduction. Or, the fish simply won't grow as big because their diet doesn't provide sufficient energy to foster growth.
Seems to me that volume biomass alone isn't enough to determine growth rates, because you could have all different distributions of biomass equalling the same volume and the end result would be very different.
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Location: Elk River, Minnesota | Volume of biomass would NOT be enough to limit growth rates by itself...But...I'm having a tough time getting my main point across about density of fish for a limited body of water...
In a nutshell, when a lake reaches a maximum level of biomass, no matter what species or variety of species lead to that maximum, the fish stop growing. The lake cannot support a having larger fish in it in the limited space it may have.
Over the years I have had muskies and northerns in aquariums....so again, not being scientific in any way, but going by my own experience here... If you put a pure strain muskie in an aquarium, it will only grow to a size that the aquarium can support...then it stops growing, but still eats like it is starving. I view a lake as being no different. It can only support so much... It is not a predator-prey relationship here...it is a basic biomass situation, where predator-prey relationship is healthy and stable,...so the populations of all stay high and quite balanced..but size is limited due to the size of the lake.
Steve
Edited by VMS 4/23/2008 4:59 PM
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Posts: 8772
| Steve,
I see what you are saying, and it makes sense. Take two lakes that are each 500 acres, with similar structure, water chemistry, and forage base. Put 2000 muskies in one lake, and 500 in the other. Wait 10 years.
It stands to reason that the muskies in the lake stocked at 1 fish/acre will ultimitely grow to a larger size during that time than the muskies in the lake stocked at 4 fish/acre.
The size and distribution of forage will fluctuate as well due to a 4x greater rate of predation. So while the lakes started out the same, because you have so many more muskies in one, over time it develops a completely different profile.
What you are saying is that both lakes would have a similar volume of biomass at the end of 10 years. The distribution might be completely different, but if you weighed all the fish in the lake both lakes would be supporting a volume of fish that was essentially the same.
So what does that mean in a lake with small muskies? How do you determine of there's too many muskies, or too much of some other species? If the biomass theory holds true, than reducing the volume of ANY species would mean better growth rates for the muskies, right? Unless you remove their primary source of prey, then you'd have smaller muskies. Or skinnier muskies, or fewer muskies, or...
I think I'm confused!  |
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Location: Elk River, Minnesota | That is more along the lines of what I was thinking.
I think this thread is dealing with the DNRs choice of using Moose Lake Muskies for the spooner hatchery this year, which has since been abandoned, but for reasons other than what the argument was about...genetically inferior muskies that do not attain any real size.
I got into a conversation with a coworker who has had property on Moose for about 20 years or so. I asked him about the fishing there and he says it is good for everything, but EVERYTHING is small...even the panfish are small. A good sized crappie right now is only about the length of your hand... He's up there all summer, and that is all they find in anything they catch...small fish. What that tells me, is there is an overabundance of biomass in the lake, thus stunted fish of all species...the lake just cannot support it all.
So...I'm not sold on the idea of NOT using those fish for stocking purposes, and further study would be a safe option...the guys over at TNB might just be a bit surprised...I might be too..
Steve
Edited by VMS 5/1/2008 10:16 AM
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