My boy had to do a science artical review and he picked an artical that talked about what happens to the gene pool when only big fish are kept? I didn’t read all of the artical, but the reseachers findings was that over time the size of the fish begain to shrink. With every following generation of fish also shrinking when the largest ones were removed.
I just thought it was interesting and was wondering what you guys think?
I am not making a position for or against catch and release just thought it was a good topic.
As for me I practice both catch and release and keeping a fish or two.
Makes sense to me. To get big, you need the genes to both get big and the intellegence to avoid predetors, including fishing hooks. Removing the large fish would also remove the possibility of passing those genes to future generations.
This principle would only apply to fish who have successful reproduction in that specific lake. Obviously taking bows from Strawberry or the nelle, or hybrids, will not hurt the chances of catching large bows in the future, except that the one fish is not still there. But taking big browns from the nell, big cutts from strawberry or big cutts or browns from DC likely would have future impacts.
I would also guess that such reasoning only works when large fish are taken in huge numbers on big lakes, or the few big fish are taken on smaller lakes.
I wonder how much of a role genes really do play compared to water conditions and available food?
I have always said, if you feed them, they will grow. I think availability of food gives you the best chance of larger fish..example, Henry’s Lake in Idaho. I know game and fish depts. in the west are reluctant to stock food, unless it is a native species.
One of the other thing that happen when you take out the bigger fish, lets use crappie as the fish …
If you keep taking say crappie over 12" from the lake after some time you will find that you are catching only crappie under 12" with very few over, why one thing it takes five years for a crappie to get to 12" and out of a batch of eggs you may only have less then ten% live to the age of five years …
On some lakes when this happens some will say they are stunted but the truth is they just need time to grow, over harvest has taken out all or most of the bigger fish…
In this state we have that with crappie in Pineview and bass in Pelican at times on some lakes we have slot limits to try and prevent this Jordanelle has no bass over 12" can be kepted so the bigger bass can help to keep the lake in balance…
Strawberry allows one fish over 22 inches to be kept. So big fish at Strawberry are being kept and look at how it affects the lake. Yup, you guessed it there are no big fish left in the whole lake.
The DWR knows what they are doing, they know how to manage fisheries. If you simply let all of the fish get big, they will eliminate all of the bait fish and food sources faster and then start eating the rest of the averaged sized fish.
I think what every lake needs is balance. There is a need to practice catch and release in some places, and there also is a need for some harvesting once in a while. I think Strawberry is a perfect example of how fisheries should be managed. Just look at the results.
I would say that there is no doubt that keeping only the largest fish will reduce the size built into their gentics.
In the aquarium hobby, you can breed certain traits into a fish population in just a few generations.
That being said, I think it would take a very long time for anglers to make a noticeable effect on the genetics of a fish population. Genetics, natural selection, and “unnatural” selection can affect the size of the fish, but ultimately, other factors will make a much larger difference.
Strawberry allows one fish over 22 inches to be kept. So big fish at Strawberry are being kept and look at how it affects the lake. Yup, you guessed it there are no big fish left in the whole lake.
You’re joking, right? As I look at the fish in your avatar that I believe you caught at Strawberry?
I guess conditions have changed since 12/29/07? [crazy]
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Genes, not food make bigger fish. Just like parents who are big, chances are their kids will be big. [/reply]
Uh, I think food has something to do with it!!!
Length of growing season is also a big factor. (small mouth in the Gorge only grow for part of the year. Lake trout in Canada only grow part of the year. Etc.)
Strawberry allows one fish over 22 inches to be kept. So big fish at Strawberry are being kept and look at how it affects the lake. Yup, you guessed it there are no big fish left in the whole lake.
You’re joking, right? As I look at the fish in your avatar that I believe you caught at Strawberry?
I guess conditions have changed since 12/29/07? [crazy] [/reply]
I think it was meant as a joke pointing out that he caught a huge fish even after they allowed catch and keep of fish over 22".[;)][;)]
Nope, it dont effect the future size at all so hook em and cook em. If theres to much fish flesh for a single meal stuff them in bottles and stack em on the shelf to be recycled in 20 or 30 years. HA!
Yes thats true, Calico Bass in the ocean grow slow no matter the food source. The bioligist say it takes a Calico to get 20’’ 5 years, there is no problem for food source. Maybe different species grow at different growth rates.
There are a lot of factors to consider . So from what I see here is that if we take the Blacksmith river- which has many many small fish- kill it off and save a few of the small fish and let them spawn- it 5 years we still we only have small fish even if the food base is there ? Not betting on that one.
Fact or myth?–When fishing regulations allow large fish to be harvested, only the small fish survive. Over time, the genetics of the population become altered and the potential to produce large fish is lost.
At first, this sounds very logical. But again, this theory is based on commmon associations most people have with “determinate growth.” We tend to think that fish growth is governed by the same rules as other animals. In contrast, fish have evolved and are genetically programmed to be very plastic and adaptive, a characteristic that serves as a long-term survival strategy. The Pyramid Lake cutthroat trout example, previously noted, where large fish were changed to small fish, then again changed to large fish, just by altering the habitat where they lived illustrates the great range of adaptablitiy that fish can undergo. Many generations of selective breeding of only small Pyramid Lake cutthroat trout had little influence on the final outcome. There is no substantial evidence that selective sport fish harvest genetically alters growth and maximum fish size."
“Birds and mammals are classified as having “determinate” growth. In contrast, fish have “indeterminate” growth. The management implications of this difference is huge. Maximum size and growth of mammals and birds is predetermined and pretty much controlled by their genetics. 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. For example, consider brook trout, one of the smallest of the trout species. In a crowded, environment with relatively little food, maximum size might be 0.25 pounds. On southern Utah’s Boulder Mountain this can be altered to increase potential size to about 6.0 pounds. Fish numbers (density) have to be reduced to allow each individual fish to have a larger share of the total food supply, but overall fish biomass supported by the lake remains the about the same. The reverse can occur just as quickly. Either way, the change represents a difference of 24 times in size (0.25 to 6.0 pounds) in a very short amount of time. Imagine changing the size of an elk by 24 times. It doesn’t happen with elk, but it does happen with fish.”
The thing to remember when considering what happens to the evolution of the gene pool is that there are multiple DIFFERENT factors acting on the population at the same time.
For instance, with a “generic” fish population, all of these pressures could possibly affect fish size. Remember that the bottom line is BREEDING success, not just survivability.
As you noted, if fishing pressure is significant, and anglers kept only the big ones, then the evolutionary pressure would push fish size downward.
However, smaller fish are more easily eaten by fish predators, which would push evolution toward larger size within the species.
Birds and mammalian predators might more easily eat smaller fish, which would push for larger size.
In most instances, larger fish have more successful spawning success and numbers. (Females have larger egg counts and bigger males dominate the “servicing” of those eggs).
Finally, the size of the fish is usually “pressured” to stay in the “niche” the fish species is in. (otherwise new “species” can form.) Usually, a species is ideally able to utilize a suitable food source so changing niche is not good evolutionarily, unless that food source is disappearing. For instance, a minnow species would take a long time to evolve into a large predator. (It does happen however, ie the pikeminnow/squawfish)
There will be more pressures than what I listed.
All of the factors will exert pressure at the same time and is cumulative. The net result can also change, depending on what factor is more important at that time. The factors may cancel each other out, and no change will be seen.
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My boy had to do a science artical review and he picked an artical that talked about what happens to the gene pool when only big fish are kept?
…findings was that over time the size of the fish begain to shrink.[/reply]
In particular, if you don’t want to read the whole document (I highly recommend you do!), then at least read the end section that addresses facts vs. myths. Your exact question of harvesting larger fish and losing the “large” genes is addressed and answered.
