I can't speak from personal experience but I believe there were some PB Magazine articles that hit on the topic. One article, I believe by Bob Lusk, warned against putting obstructions in front of anywhere water overflows. If debris gets clogged in the net, wire mesh, etc then the water will find the next path of least resistance which might be washing out the dam. As far as fish escaping, I believe I have read that LMB (assume your trophy are LMB) tend to actually stay at home if the water is moving fast. They will escape if the water is still. So at my place if the water is moving fast through the overflow they will likely stay in the pond but if the water breaches around the dam the water is covering much more area and therefore moving slower so they might head out that way. I believe that was also PB Magazine article.
There are folks here that are probably more help and might even be able to provide a link.
