RAH, I agree with your statement, for the overall numbers of fish in a pond. But, for certain species, like the trout that Cecil raises, each fish has a high $$ amount associated with it, so even if the fish lived, it would have a spear mark in it and it would not be marketable for Cecil.
I've had them sit on top of the fish cages and fill their crop. If that happens day after day, there can be some appreciable losses. Same during spawning season. GBH can do a number on the spawning fish.
But not to the extent that Cormorants can do to a pond!!
Like Scott said my ponds aren't really recreational ponds. The trout take two years to get them to harvest size and at that time can be worth up to $100.00 each depending on their condition, species, and size.
The trout unlike large bass and bluegill can cruise shallower and be more naive when it comes to the GBH. I've seen the trout dart into water only a few inches deep for a pellet, which makes them very vulnerable.
Additionally the grubs, of which the GBH is part of a cycle can reduce the value of my fish if they are visible.
