I don’t want to start a big controversy, and I’m not a biologist or even the sharpest knife in the drawer, but I think that you are addressing items that are not related to the original question. (does keeping the bigger fish hurt the gene pool?)
Your premise that the size of the Pyramid Lake fish have returned to their original size is way off the mark. Have you seen pictures of the fish caught from there in the “old days”, compared to the current size?
Granted there are many factors that alter the size of fish and their growth rate as you have pointed out in your Pyramid Lake example. But don’t you think that removing (catching) the large fish from Pyramid Lake altered the gene pool, resulting in smaller fish?
This is proven in fish, deer, elk, all critters, and even people.
Genes are a major factor in breeding all animals.
EXAMPLE: Race horses don’t come in off the farm.
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Fish aren’t mammals. They don’t grow like mammals. They didn’t evolve like mammals.
It’s called determinate growth vs. indeterminate growth. When an elephant is born, it is pre-determined that the elephant will grow larger. Fish don’t work this way. Their size is not predetermined through genes. They have the ability to grow big based on environmental factors. An elephant is gowing to grow big, even in a poor environment. Sure, it might starve to death and not grow to its full potential, but it still grows bigger as it gets older. Fish don’t. Fish can grow, then shrink, then grow. They can also stay at a particular size for many years, then all at once grow big.
Your premise that the size of the Pyramid Lake fish have returned to their original size is way off the mark.
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Actually, it hits the mark dead center. Bulls-eye!
Saber – I highly recommend that you take a couple minutes and read the article in it’s entirety. I think you’ll have a change of mind. Reading the article can’t hurt anyone. It will certainly give a greater understanding to anyone that reads it. Is that a bad thing?
[reply]Your premise that the size of the Pyramid Lake fish have returned to their original size is way off the mark. Have you seen pictures of the fish caught from there in the “old days”, compared to the current size?
Granted there are many factors that alter the size of fish and their growth rate as you have pointed out in your Pyramid Lake example. But don’t you think that removing (catching) the large fish from Pyramid Lake altered the gene pool, resulting in smaller fish?
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When it comes to Pyramid Lake, the history becomes important. First, in order to answer your questions, you must understand that two species of Lahontan cutthroat evolved–one that evolved as a river dweller and the other a lake dweller. Only the lake-dwelling strains of Lahontans ever achieved huge sizes.
In the early 1900s irrigation practices left the spawning habitat of these huge lake-dwelling Lahontans high and dry and, as a result, the lake(s) lost this strain of fish…some thought these fish were lost forever.
However, and luckily, someone in the far past transplanted some of these Lahontans into some tiny streams in the Pilot Mountains of extreme western Utah. DNA analysis of these remnant fish confirmed that they were pure strain Lahontants like the original lake-dwellers.
Since their discovery, brood stock populations of fish with these same genetics have been developed and only recently begun to be restocked into Pyramid Lake. Biologists are very optomistic that these fish will once again achieve huge sizes…perhaps confirming their beliefs were Utah biologists discovery that these same little Pilot Mountain fish were achieving massive sizes in brood stock ponds that didn’t demonstrate the same environmental conditions as Pyramid Lake.
The time frame between the loss of these original lake-dwelling fish and the stocking of the new pilot mountain fish has seen the lake stocked with the river-dwelling species which didn’t have the original genetic makeup to achieve large sizes. Large numbers of the pilot mountain fish have only been stocked into Pyramid Lake in the past 6-8 years…it could take 10-15 more to really know what the growth potential of these fish in Pyramid Lake is.
I read the two articles referenced, and see where you obtained your facts.
I agree that the information presented seems factual, and was written by credible sources.
Like I said, I’m not the sharpest knife in the drawer, and even though some of the information doesn’t make sense to me, I can’t dispute your position.
Seems like a old dog can learn new tricks. Thanks for the postings.
Yes, I was joking. Sorry, I tend to be a smart “A” once in a while.
Heavens! Sorry if I made you sorry. Mine was a joke too. I had a feeling there you were going for tongue-in-cheek. I guess that emoticon just doesn’t convey that properly. Kinda coincidental, too. I had pm’ed TD last week asking for a ROFLMAO icon, and he responded that since this is a family-oriented board, we can’t have that. OK, howz about a ROFL icon? Is there a difference??? Just want an emoticon that’s on it’s side laughing. As I wrote to him, there’s some posts here that have made me almost spit out my Scotch in laughter. TD- you out there? See the damage this is causing? (insert ROFL emoticon here)
The artical my boy pulled up was in a controlled environment. So in that case I would say that a scientist can control the size of fish by only letting the smaller one’s reproduce.
I totally agree with the artical and it does make sense. I just didn’t have the info for what happens in the wild and that is why I made the post… Thanks for all the information it was very informative!
BTW he just had to use the artical for a artical review.. Not for research! WHEW!!! [;)]
That’s a great question. Does it matter how big an animal grows? The DNA doesn’t change just because you grow bigger. Once an animal’s passed its DNA on to offspring it shouldn’t matter should it? For example, if a man has a baby when he’s seventeen and then has another one at 21, after he’s grown three more inches, isn’t he still passing the same DNA on to both kids?
Fargo – you are exactly correct. Let’s have a look at that from a fish perspective:
Two lake trout are hatched from the same parents. They’re brother and sister. Same DNA. Over the course of their life, one fish becomes pisciverous, the other continues to feed on insects. The pisciverous fish becomes a 40" 60lb lake trout. The insect eating fish becomes a 29" 2lb skinny fish.
If you harvest the bigger fish, and leave the smaller fish to do the spawning, will you get smaller fish as a result?
No. The DNA hasn’t changed. The small fish has the same DNA as the large fish. Environmental conditions produced the size discrepancy.
Smaller fish as a result of harvesting large fish is a myth.
Everybody is missing another part of the picture here! When you have so many fish that are sexually mature, they make what we call “the breeding population”. What keeps every higher organism (humans included) genetically healthy is by making sure that there is enough variance within that population. (this is why inbreeding is bad). If the breeding population goes down enough, it will mean that certain small genetic mutations that can cause diseases or defects will begin to come to the surface in the resulting offspring, thus creating a less healthy population in the long-run.
While it might not directly affect size to begin with, it can in the future. Bodies of water that are supplemented with stocked fish won’t have as much of a problem, but naturally sustaining ones sure will!
The only changing variable in this experiment is the removing of the larger fish. So in a controlled environment this research is telling us that it’s not a myth. According to this research and this type of fish.
Like RyanCreek said that it may have an effect over generations or in the future.
Yup. I agree with you. You have to set up controls like the DWR has. But the question was not about Strawberry or about regulations for a particular fishery. It was Does the gene pool affect the size of a fish? What do you think?
Could it be that the reason they only let you keep 1 fish over 22" is to let some get big… like yours? And to have big ones reproduce?
Without seeing the actual study results (I did read the article), I do see some problems with the little experiment.
The site says, “In two of the tanks, he kept removing the biggest fish, to copy what commercial fishermen do in the ocean. He found that this caused each generation of fish to grow more slowly than the one that came before it.” Obviously, the tanks become the fishes’ environment…therefore, in order for the experiment to have any merit a couple of variables must remain constant: 1) amount of food fed to the fish 2) the number of fish within the aquarium 3) Timing of when the fish were removed.
The site, however, says nothing about these variables and whether or not they did remain constant…it only says that the largest fish or smallest fish or random fish were removed. But, the big questions remain: 1) How many fish did the tank have to begin with? 2) How many fish were removed? 3) How much food were the fish given?
If any of these variables did NOT remain constant, the results would be seriously flawed.
So, let us assume that as a collegiate professor, he is smart enough to keep all his variable constant. There is still one major problem with his study: he was removing these fish before they had a chance to breed. In nature and in the world’s fisheries, this is rarely the case. True, fishermen selectively harvest the largest individuals…but normally these fish have already passed their genetics on.
In real life situations and in real fisheries within the state of Utah, one thing is for certain: growth rates, size potential, and reproductive rates are NOT changing. Utah has over 100 years of stocking data, growth rate data, and recruitment data…in that time frame, NOTHING points to the conclusions that your article claims.
That makes sense. Removing them before they have a chance to spawn, would be a majior problem. That would not happen in the wild. I’m not disputing Utah’s data in any way, we already went down that road with the big Yuba debate.. hehe.
So what do you think.. Put everything aside if you had the perfect expierement do you think it would make a difference when the biggest fish does not spawn? I would think yes.
In the wild? Not a chance. Too many things involved.
Thanks for all the information that you give in the discussions!
The Pyramid lake Lahontan cutts show BOTH the effects of indeterminate growth and evolutionary related genetic effects. While the last remaining Pyramid lake fish were stuck in a small stream near Pilot peak, and not exceeding 10 inches in length, Lahontan cutts from other sources were put into Pyramid lake. The food opportunities were the same as for the original inhabitants, yet, because these fish didn’t have the GENETIC characteristics to utilize that food source (derived by co-evolution with the prey of this lake) the maximum size of the other Lahontans was only 5-10 lbs, even with the same generous food source. It is hoped that the original inhabitants will again achieve the original size with proper management.
Next, Re;
“Two lake trout are hatched from the same parents. They’re brother and sister. Same DNA. Over the course of their life, one fish becomes pisciverous, the other continues to feed on insects. The pisciverous fish becomes a 40” 60lb lake trout. The insect eating fish becomes a 29" 2lb skinny fish.
If you harvest the bigger fish, and leave the smaller fish to do the spawning, will you get smaller fish as a result?
No. The DNA hasn’t changed. The small fish has the same DNA as the large fish. Environmental conditions produced the size discrepancy."
All individuals have slightly different genetics from each other. It applies to us, it applies to fish. If these slight differences control which fish are more likely to become large or small AND if either larger fish OR smaller fish breed more and have more offspring than the opposite type, then evolutionary change will take place and the average will go up or down. The changes will need to consistently take place over several generations to see an effect.
Finally, the posted management plan article mainly discussed trout. In about 95%+ of our heavily utilized trout (lake/reservoir) fisheries, (esp. bows) the main (or only) mode of reproduction is determined by when the hatchery truck arrives and how many fish go into the pond. When planting is the main mode of propogation, evolutionary/natural selection processes do not apply AT ALL, since they require natural reproduction to exert any control. Strawberry was mentioned. Both cutts and bows are planted heavily there so natural reproduction is not important for maintaining the health of the fishery, and also with the slot, cutts are protected from harvest past the point of reaching sexual maturity. Thus harvest has no effect on who is breeding anyway. Natural selection pressures are more likely to be seen in our warmwater species since they mainly do require natural reproduction to survive.
Reference on Lahontan cutts; Trout and Salmon of North America, Robert Behnke pg 211-216.
Yeah, I guess I didn’t really look at your question very close.
I don’t know about the gene pool or any other scientific stuff. I just go out and hope something bites my line. Big or small, a fish is a fish and I like fishing.
[;)]
It may not chang the genetics but after so long you will have a lot of the upper end of the fish at that size do to age of the fish and the number of fisherman taking fish…
And in some types of fish it shows more then others, not all types of fish will grow to the same size in the same time with the same amount of food…
Don’tcha wish you were a fish sometimes? We humans are always fussing about weight and most of us should eat less. When we reach a certain height, we stop growing upward, but not outward.
Do you think one fat fish ever told a skinny one “It’s a gland problem”?
