Quote:
Originally Posted by HunterDave
I'm all for leaving the biggest fish in the lake, I just don't understand where genetics has anything to do with it. There could be thousands of smaller fish in the lake that have his genes that are just as healthy, etc as the big one except they just haven't grown to his size yet. There might even be smaller fish that have genes superior to the bigger fish but they just haven't gotten as big as him yet.
I don't buy into the theory that just because a fish is big it's genes are superior to the smaller fish in the lake. Now, if his genes made him grow bigger faster than the other fish in the lake, then that would be a different story.
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You're absolutely right Dave, the small fish can have the same genes as the larger fish, they just haven't had the chance to grow yet. The main factor that needs to be considered is genetic diversity. In any naturally reproducing population, there will always beo some genetic diversity. This includes within the genetics that affect growth rates and in turn size. There will always be some genes that allow some fish to grow larger.
Here's a simplified example to what can happen to the genetics of a population if only large fish are kept. Say we have a lake with a large population of pike, and within this population we have two categories of fish based on growth rates. One is slow growing and reaches sexual maturity around 24 inches and maxes out around 36 inches by the end of its lifespan. The other grows quickly and reaches maturity around 36 inches and maxes out around 50 inches.
Now say that fishermen keep the fish around 25-30 inches most of the time, they are going to end up taking some fish with the "slow growth" genes, and some with the "fast growth" genes. So absolutely some of the fish in that size range are going to have the stronger genes, and in turn some of them will get killed, but overall the proportion of the two gene types will remain about the same since both are being harvested. Hence the population will maintain are similar size-class distribution.
Now on the other hand, if only the 36 inch plus fish were being harvested, then the fish with genes for faster growth would be the only ones harvested, and that would affect the genetic balance of the lake.
Sorry I just read through your post again and did notice that you commented on genes that affect growth rates. What it boils down to is that genetics will affect growth rates so an extent, sometimes more than others. So a large fish won't necessarily have better genetics than some of the small fish, but chances are it will have better genetics than the overall average of the fish in the population.