Im gonna play the devils advocate here.

There has been tons of research that looked at the effects of recreational fishing during the spawn to the recruitment (nest success) of bass populations. Tournament fishing has garnered particular attention. A wealth of scientific literature exists showing no effects. Anybody can find this literature if they want to. With that said, many states ban fishing for bass during the spawn. CA obviously isnt one of them.

As far as seeing abandoned nests. How do you know they are abandoned? My observations through the years is that many lakes that get tons of pressure during the spawn causes the bass to spawn at night. Ive seen this many times. I fish during the day and see empty nests, then when its dark I run with a spotlight. Those empty nests will have bass in them at night, and Ive observed lots of them spawning at night (you know, rolling on there sides and that whole thing).

And like Don pointed out, we can only see a small percentage of bass nests, so logical thinking says we may only be affecting that small percentage that we can see. When you factor in the survival rate of bass fry per nest (small), its easy to come to the conclusion of no effect.

Just a different perspective.

PS: I had no idea Don was that old, no wonder he has poopy pants all the time.