Judging by the fact that all the fish were the same size, had been filleted the exact same way, were all basicly in the same state of decay, and were all at a boat launch I would have to go with it being a small scale commercial fish shop or smoker using that launch as a dump site. Its fine though, its good for the river, ALL hatcheries dump the carcasses of the roe salmon they recover back into the rivers they came from... I feind for the day I get ticketed for throwing a fish frame back in the river... the state breaks its own law all fall and winter, just go to gnat creek here in about two weeks.. mounds of fish dead right under the bridge-
