It may be a case of seeing tie up corks in the river and not a net. I have had many clients exclaim,"Hey I thought the nets were out?" when they see these corks. The tie up corks hold the lead line and cork lines on top of the water so that the fisherman can get to them. The way to tell is that the corks will be about a foot apart. Tie up corks are about 6 feet apart. I'm not sure that this is the case here but may be?