Tagged FG Mack Hooked Again...25 Years Later

[wormandbobber]

This fish is not at all unusual...you see this exact same thing at Fish Lake all the time (every year in fact when the DWR does fall spawning). The reasoning is simple: it all comes down to the bottleneck lake trout must get through in order to start putting on weight and their food sources. The lake trout in the article was never large and it didn't suddenly shrink because of old age; it simply has not been utilizing the same food sources that the large lake trout are using. In other words, some lake trout never switch over to a fish diet and thus never reach large sizes. Read the following link to lake trout and their sizes from Fish Lake; it directly shows and speaks about this very thing happening.
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[wormandbobber]

Just a quote from the above article I posted: "We found relatively few lake trout between 21 and 30 inches.." That is the bottleneck I spoke of..."By contrast, 1979 length-frequencies were dominated by lake trout between 25 and 35 inches. Our study found that lake trout can grow from 20 to 30 inches in < 5 years and then spend the remainder of their lives between 30 and 40 inches. In addition, the high exploitation rate (16%) of lake trout at this size could potentially remove 60% of all individuals before they reach 30 inches. Even more important, a lack of adequate forage may prevent some lake trout from exceeding 20 inches in length. Donald and Alger (1986) reported that indadequate forage prevented mature lake trout in a Canadian lake from reaching even one pound."

"Growth of individual lake trout is highly variable. Highest growth rates were observed for lake trout 25 to 30 inches in length. A review of the food habits of lake trout at this size reveals that these fish are entirely piscivorous. At age nine, seven of the recaptured lake trout from the 1991 stocking were less than 20 inches, while three were between 20 and 25 inches, and seven were > 25 inches. It appears that some individuals never convert to a fish diet and consequently never reach lengths >22 inches."

The fish mentioned in the article above is hardly surprising...especially since both Wyoming and Utah fish managers have been saying for years that Flaming Gorge doesn't have adequate forage to support the lake trout population. So, because the forage isn't adequate, a bottlenece develops where only a few fish are able to squeeze through and reach trophy sizes. Age is definitely not the key determining factor for lake trout sizes...but diet.
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[PBH]

hashbaz -- thanks for taking the time to read the article, and for being interested in learning something new -- another concept that many fishermen struggle with...


1. From page 4: "Fishermen often underestimate how fast trout can grow and overestimate the time it takes to grow a trophy trout. Large trout are often a function of fast growth rather than old fish"

2. From page 8: "Fact or Myth? Catch and release fishing regulations allow fish to live longer and thus, grow larger...
...The assumption that released fish are predestined to become large with old age is false. By now, this should be obvious based on what has been discussed about population density and indeterminate growth."

You mentioned environmental conditions. Is Flaming Gorge a good environment to produce large lake trout? You bet. Do Lake Trout have the genetics to grow large? You bet. So, what happened with the fish in question? Why was it so small for its age?

To find out, you can read another very interesting paper on another of Utah's famous fisheries, Fish Lake: [url "http://www.wildlife.utah.gov/fishing/fish_lake/fish_lake_lake_trout.pdf"]http://www.wildlife.utah.gov/fishing/fish_lake/fish_lake_lake_trout.pdf[/url]

From this study, we find that:

1. From page v: "...it is clear that many lake trout do not convert to a fish diet and remain at smaller sizes compared to their piscivorus counterparts..."

2. From page 5: "Growth rates among individual fish were highly variable. Age 9 lake trout, stocked in 1991 and recaptured in 2000, ranged in size from 15 to 33 inches.

3. From page 6: "Lake trout began consuming forage fish when they reached 18 inches in length. By the time they reached 25 inches they switched to an entirely piscivorus diet."

4. From page 8: "...lake trout between 18-24 inches switch from a diet insects and zooplankton to one dominated by forage fish. However, it is apparent that not all lake trout in Fish Lake are able to make the transition to a piscivorus diet."


So, what can we conclude concerning the fish caught by the biologist?

A. It was an old fish
B. It was in a good environment for growing large fish
C. It had the genetics to grow a large fish
D. It didn't grow large
a. Because it didn't utilize its environment
b. It never made the switch to an entirely piscivorus diet

Should this be surprising? No. If you understand the what's and the why's of fish growth, this should not be surprising at all. Quite simply, the fish was content, or could not make the switch from, eating insects. It never made the switch to a strictly fish diet.

Some of you guys are taking this way to personal. There is nothing wrong with using studies to further understand the biology of our fisheries and the fish in them. If you understand it, it will only make you a better fisherman. Is that bad?
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[hashbaz]

I have limited time on my lunch break and I have not yet taken the time to read the Fish Lake article (I assume that W&B and PBH are refering to the same article). But from what you two have quoted from the Fish Lake article, it sounds to me like it makes a MUCH better explaination of why a 25 year old fish was still so small.

PBH, It just seemed funny to me when you stated:
"Size is not a factor of age." Interpreted literally, a 1 day old lake trout is capable of weighing 30 pounds if conditions are right.

I think what you are meaning to say is something more like this:
"Age is only one of many factors affecting the size of a fish." I think all of us can agree on this.
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[wormandbobber]

[reply]"Size is not a factor of age." Interpreted literally, a 1 day old lake trout is capable of weighing 30 pounds if conditions are right.

I think what you are meaning to say is something more like this:
"Age is only one of many factors affecting the size of a fish." I think all of us can agree on this.[/reply]

Actually, what he should have said is this: "Age is not the determining factor for size."
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[PBH]

[reply]
... it sounds to me like it makes a MUCH better explaination of why a 25 year old fish was still so small.

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Let's take this a step further:

That 25 year old fish (heck, let's make it 30)that is only 24" long -- what happens to that fish if on its 31st year of life it finally makes the conversion to a strictly piscivorus diet? BOOM! That fish VERY QUICKLY makes a jump from 24" to 35". What happened? He learned to eat.

Fish are very plastic. They can grow (if conditions permit) very quickly. They can also remain very small - yet healthy - under certain circumstances.
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[Wyobraz]

I can't find this online anywhere to paste a link but I recieved this in a Wyoming Game and Fish Newsletter afew years ago. Here is the highlights.

Flaming Gorge Lake Trout will mature between 6 and 7 years of age at a length of about 19-20 inches and weigh around 2 1/2 pounds. They will stay at this length and weight unless they switch over to a fish diet. Most Lake Trout in Flaming Gorge will successfully swapp over to a fish diet when they are 4-5 years of age 15-17 inches in length as will weigh around 2 pounds. After Lake Trout in Flaming Gorge has successfully swapped its diet over to fish the "Average" wieght gain is 1-2 pounds per year, with the available forage of Rainbow Trout, Kokanee, and Utah Chub.
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[tightline]

So if genetics are not a factor and I buy 50 rainbow trout and throw them in a pond all at 6" from a certified hatchery. I feed them all the same diet which they all eat. They all live in the same conditions for 3 years, same water, they have the same amount and type of food available to them yet some are substantially larger than others. And it has nothing to do with switching diets because all any of them really ate was pellets. And ate very well I might add.
What is the determining factor?
Some fish grow bigger faster because of genetics! Some fish also are more aggressive because of genetics! It is a major factor and you can say otherwise until you are blue in the face. I have seen it many times first hand and through raising many generations of fish and selectively breeding them for specific results over many generations. You can breed out the size of a fish to be large or small with selective breeding, just like color, or body shape or anything else.
PBH, I really wish that you would get off of the soap box that genetics doesn't matter. I assure you that genetics are a big part of the equation.
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[jacksonlaker]

PBH, I'm curious as to why most pacific salmon can go from fingerling to 40 lbs in just 4 years. Is it just the type of fish ?? Salmon dont seem to be much different than trout, and I still find their growth rate amazing ..JL
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[hookemup]

Is some kind of "bible" available? Written and published by the not cocky, extremely successful, wonderful....etc. PBH that could enlighten all of us losers (well me anyway) about how the fish world really works?? I didn`t think so!

hook`m & cook`m y`all
DARREN

Please watch the language. kentofnsl

[PBH]

Wyobraz -- that seems very near to the findings at Fish Lake. Remember, an average divides the total growth over a period of time. It doesn't necessarily mean that the growth actually happened that way. They may average 1-2 pounds per year, but they might have actually gained 4 pounds in 1 year, and none in the next -- thus an average of 2 per year. Gain 10 pounds in 3 years, then none in the next 7 and you still have a yearly average of 1 pound per year.

Once a lake trout of 24" completely converts to a fish diet, it will grow very fast for a period of time. It will eventually reach a size where it will not be able to sustain that growth rate. Fisheries managers ideally would like to keep fish in that maximum growth rate area. That is where the fishery is at it's best.

Tightline -- slow down. You're taking things too literally. I have not said anywhere that "genetics don't matter". Obviously genetics are an important part. But they are not the limiting factor in the majority of Utah's fisheries. Again, look at the fish in question. That small lake trout had the genetics to grow large. Why didn't it? Because it didn't switch to a piscivorus diet. It's genetics were there. But it didn't grow large.

Look at the Lahontan Cutthroat. Historically they grew to huge sizes. They were then thought to be lost until a population was found in the Pilot range. Those Lahontans in that small creek were very small (10"?) and had been so for over 100 years of breeding. Were the genetics to grow large lost? When those same 10" fish were put in larger ponds they quickly started growing cutthroat over 10 pounds! We do not know how large those fish have the potential to grow at this time -- but it is very obvious that it was environment that forced them to 10" in the streams of the Pilot range, and not genetics. The genetics are still there.

Genetics are important -- I've never said otherwise. But, when it comes down to it, it is usually not genetics that are the limiting factor in fish growth and size.

You mention selective breeding. This can be accomplished in an aquarium where you can control which fish is fertilizing the eggs. In a natural environment (like Flaming Gorge) you cannot control this selective breeding. The genetics of the large fish are being mixed along with the small fish. There is no way to selectively breed out the size (or other characterisitics) in a natural environment.

jacksonlaker -- Look at their environment. They head out to the ocean and begin a vicious feeding frenzy off rich oceanic food sources that provide an environment of FAST growth rates. Perfect example of what I'm talking about. It's not how long the fish lives, it's how well it takes advantage of it's environment and how fast it grows. It's no different than a Steelhead. Steelhead are rainbow trout. Genetically identical. So, why do steelhead get so much bigger than an average rainbow? It's not genetics, it's environment. Steelhead are an ocean going salmonid that take advantage of a richer food source -- or a better growing environment.
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[wormandbobber]

[reply]PBH, I really wish that you would get off of the soap box that genetics doesn't matter. I assure you that genetics are a big part of the equation.[/reply]

Again, another example of where someone spouts off based on emotions rather than simply doing a little reading and educating themself.

Had this person simply read the material PBH presented, this quote and the whole emotional response probably would not have been made; however, here we are again:

"With fish, maximum potential size is determined by genetics, but growth and actual size attained is more a function of the environment. Fish grow to match their environment."

Certainly genetics make a difference, but genetics play a minor role in determining what sizes fish attain in the wild.
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[tightline]

I did read the material and many times PBH has contradicted that which he refers to or even his own past posts. I am not saying you don't know your stuff, but who is to say it is not genetics that caused that fish to have the disposition of not hunting down other fish. Some fish are very agressive while others are not. This is all of the same species of fish. I have found it can be selectively bred out of a line for either disposition. Agression means that they will switch to eating other fish more quickly and therefore grow faster and many times it means they will be easily caught.
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[southernman]

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[black][size 3]I don't place much value in this or any published opinion. The subject is totally off the matter being discussed.[/size][/black]
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[size 3]A few years ago, the same group of "experts" that are trying to feed us the global warming story today, were trying to convince us of a soon to occur ice age.[/size]
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What's happening is so noticeable that scientists can track it from space. Satellites measuring when land turns green found that spring "green-up" is arriving eight hours earlier every year on average since 1982 north of the Mason-Dixon line. In much of Florida and southern Texas and Louisiana, the satellites show spring coming a tad later, and bizarrely, in a complicated way, global warming can explain that too, the scientists said

[url "http://news.yahoo.com/s/ap/20080319/ap_on_sc/warming_spring"]http://news.yahoo.com/s/ap/20080319/ap_on_sc/warming_spring[/url]
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[PBH]

[reply]
I did read the material and many times PBH has contradicted that which he refers to or even his own past posts.
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Where have I contradicted myself?


Again, it can be selectively bred in an aquarium where you can control which individuals are doing the breeding. But in a natural setting, like Flaming Gorge, you cannot control which individuals are doing the breeding. So, you can't say that the fish in question remained small due to genetics. It is obvious that the small lake trout in question never converted to a fish diet. This is not a genetic result.
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[doggonefishin]

Re: "you can't say that the fish in question remained small due to genetics. it is obvious that the small lake trout in question never converted to a fish diet. This is not a genetic result."


It IS obvious that this fish never converted to fish, but why was that? Did it make a conscious decision to live an "alternative lifestyle"? It had within itself some characteristic regarding behavior that caused it to not switch to fish eating. There was no food bottleneck in Flaming gorge in 1983. There was no bottleneck of food in the HATCHERY where this fished lived before planting. Unless this fish can blame his parents or the Wyo DOW for emotional trauma in his training, the reason for his individual traits causing him to not eat fish is his GENES wired his brain and his brain instructed him to eat lower on the food chain. So, yes it is a genetic result.

The biologist that originated this discussion probably has forgotten more about indeterminate growth that everyone on here currently knows. These are quotes from his article posted by Wyobraz.


"A fish's genes also determine how large they will grow. Some fish are programmed, if you will, to be large and others, small," he said. "That applies to fish from wild populations to those reared in a fish hatchery. There was plenty of food for this one lake trout to eat when it was stocked 25 years ago and it only grew to be two and a half pounds."



"When you think of the record lake trout taken out of the Wyoming portion of Flaming Gorge Reservoir, 51 pounds, this fish paled in comparison in size, but its capture allowed fish managers an opportunity to learn more about fish genetics, age and growth of lake trout in the reservoir," he said.


It is clear that he views genetics as an important part of the question regarding this fish. Sorry if I am beating this dead horse one more time.
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[Saberfish]

[black][size 3]It's written on the Internet, it must be true.[/size][/black]
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[size 3]They did neglect to mention that one of the major causes of the global warming is bovine flatulent. [/size]
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[size 3]I won't know if that is true, until I look it up on the Internet.[/size]
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[tightline]

Dog,
That was well stated.

When we take out the aggressive, fast growing, easy to catch fish we are in fact doing something along the lines of selective breeding. By eliminating those genes that have a higher potential to reach the full size of any one species and leaving the runts to reproduce.

PBH your life is a contradiction. You are a school teacher who spends much of his day on the web, need I say more. Teach your students to think for themselves and not just follow the system. The world doesn't need any more cheerleaders! The system is not always right no matter how much schooling or credentials some people working for the system may have.

Pres. Bush has a degree from a much more credited university than you or I went to. He even managed to get pretty good grades. He also holds a position and has credentials that none of us compare to. It doesn't mean he has any clue what he is doing!

Common sense is becoming a lost a rare thing in the world today!
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[jacksonlaker]

Are you saying this fish might be gay??? LOL
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[doggonefishin]

Re: "Are you saying this fish might be gay??? LOL"


Uh, no, unless our science unexpectedly discovers that fish can make higher level conscious decisions about behavior and "lifestyle". But hey you never know. The fish did come out of "Flaming" Gorge [shocked]

I think I am done with this one. Tight lines.
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