As the Susquehanna's population has declined, the Allegheny's smallmouth population has taken off.
So, what lessons can we garner from this? The Susquehanna has all that rediculous habitat. The Allegheny has nothing like this at all. This hasn't changed, of course. However, the water quality and possibly the water stability of the Allegheny has gotten much, much better. Most water in the Allegheny that I fish comes from resiviors (Tionesta and Kinzua). I don't have any information about the river flows from 15 or 20 years back, but one thing that I have heard MENTIONED was that the Army Corps would shut the flows way down to keep water in the resiviors for water skiing over Memorial Day and what ever else. Perfect, right? So this water drop would leave a lot of spawning beds, which I found to be in about 18 inches of water, high and dry, killing all the eggs. So, like the Delaware, it's a water management issue.
The next big issue for the Allegheny was sewage pollution from all the cabins, camps and houses along it's banks. Anyone who's traveled along this river, especially the upper parts, will recognize it as a nearly continuous residential city, miles long, stuck in the middle of relative wilderness. All the sewage from these residences put a great hurtin' on the river's ecosystem. As a child, I remember it as being choked with that milfoil or coon tail weed and it smelled like dead carp. To the chargrin of the "Gumment cain' tell me what ta do" crowd, new regs made modern sewage systems and treatment the law. Since then, EVERYTHING has gotten better. What I believe, and it's only a hypothesis, is that the 1st year survival rates got a lot better. A reason for this is that the improved water conditions allowed more mayflies to thrive and provide baby smallies food back in the areas they live. There are loads of little mayflies sitting on the water throughout the season an I see baby smallies picking them off in the eddies and deep rock water. While smallies are fairly pollution tolerant, the mayflies are not. Cleaning the river intiated this survival chain that has the smallmouth population growning.
Now,the Susquehanna is so HAMMERED with effluent and runoff, it jumps right out of my paradigm. Have you frequenters of the Susquehanna noticed a drop-off in mayflies? This could be one reason, but if you dump enough chemicals and sewage into a river system, it ruins everything.
Syl