Originally Posted by wt bash
I had always wondered about this when it comes to our small local streams. This is obviously alot heavier as the entire ecosystem in one way or another relies on salmon. Man Ard I'm sorry to hear this, have you speculated as to what next season holds or is it far to early to make any predictions as to fish and wildlife health?
I saw plenty of these type events in the tightly folded mountains of Northern Pennsylvania over the years Bill. As you can imagine flooding has a negative effect on any stream and depending on each individual watershed the rebound time differs. One of the worst things I personally monitored was the occurrence of anchor ice in nearly all of the Francis Branch of Slate Run many years ago. Low water throughout the fall resulted in a drought like condition going into winter. This calamity was followed by a dry winter with virtually no snow covering the ground or stream. Now enter the destroyer; sub zero temperatures that caused the shallow areas including almost every tail out and their gravel beds to freeze deep into the stream bed. The little stream holds a population of brook trout with a spattering of wild brown trout. Both of these species are fall spawner's, and of course they use the shallow upwelling current flows at the tail outs of the deeper runs for the nesting process. I hiked from one tail out after another using a large camp axe to chop through the thin ice revealing the frozen gravel extending below. As the years and fishing seasons went on after that winter it became increasingly obvious that there was a 'hole' in the generations of fish in the branch most likely caused by the freezing of the spawning beds.
Flooding I presume can produce one of these 'holes' in the generational sequence of trout that could be recognized in a stream if you keep records of your fishing on that stream. With indigenous species like trout a loss of young of the year in any degree can be sustained due to the fact that not all of any given years young will perish. In each season following a flood or anchor ice event there will be adult and sub adult survivors. This is in large part due to the fact that trout have relatively long lives and are programed to survive such events as adults.
The problem here is that one can not look to next spring as any measure of what may or may not happen as a result of severe flooding this fall. The species in question enter the rivers as adults in 2012 and by fall have completed the spawning. The eggs from that spawn will not mature into the alvin stage until early spring / spring. Once the alvin have reached the fry stage and left the gravel where they hatched it will take anywhere from 2 - 6 years (depending on species) for any adult examples of that 2012 spawning to return to their natal rivers or creeks.
The larger the river the better the chance for survival during a flood. In the case of fish that spawn in smaller creeks, depending on the gradient of the creek bed they may not be so lucky.