I'm not sure that the gravel infill either helps or harms over the long term, it has been happening a long long time, that's part of the karst geology as I understand it; most of the gravel is sucked into the streams from hilltop sink holes, isn't it? There are sink holes where there were none fifty years ago and more numerous holes where they were back when, do the hundreds of earth tremors that we experience each year have something to do with this? I own about a quarter mile of limestone bluff and the leaching of minerals/formation of stalactites etc. is visually obvious over time, how does this chemically affect the streams?
When I look at a creek and see no mounds of mussel shells, no hellgrammites , no numbers of crayfish I don't expect to see numbers of large fish and I don't believe catch and release will improve the food base. I suspect that over a long period the catch and release and the size limits won't make a real difference.
During the last sixty, or perhaps the last thirty, years (or maybe this is a thousand year trend) there has been some change in the water chemistry that is harming the life forms? Frogs, there are more in my yard and field than on the creek and I've not heard a bull frog in decades. So is it unnatural that selection that predators are adapting to a less bountiful prey base?