Actually I was told by a conservationist that jack springs should be killed and not allowed to spawn because they carry a defective gene which is carried on thorough the offspring. The reason they return early is because they carry that defective gene.
I don't know how much truth there is to that, but that's what he said. Just sharing the info.
A conservationist that advocates 'genetic cleansing' does not make sense to me. IMHO, they are exterminationist that are trying to fool people that may not know any better.
There are some genetic characteristics that are bad for the individuals concerned, but good for the whole population. An example of this is sickle cell anemia. It is bad for individuals where it was expressed, but good for those who are just carrier --it gave them imunity to malaria. Hence, the populations' survival is somehow safeguarded as far as malaria is concern.
Now, as far as the jack spring is concern --they have the ability to get through obstacles that a large chinook cannot. I think this is specially important characteristics in cases where streams are partially blocked. They will be able to get through and fertilize the eggs. Their offsprings may or may not be expressing and/or carrying the genetic characteristics. So I believe that they are important in the populations' survival.
As a conservationist, I seek to understand the reason why things are the way they are naturally. This way I would not destroy things that nature and/or God has created.