I saw the same thing down on the Wilson river a few years ago while steelhead fishing. I stood on a bluff overlooking the water and watched a bunch using a casting net and they successfully landed a steelhead. I got them to look up at me and acted like I was impressed with their success. Then wrote down the license of the only vehicle in the area and went to call ODFW. A State Trooper met me and we tried to find them unsuccessfully. The Officer called me later that evening to let me know that they had been tracked to an apartment in Beaverton where they had a freeze full of fish that they admitted catching with the casting net...... Book 'em Dano.