On the Klamath River a few hundred yards up stream of the junction of I-5 and CA-96 are a pair of rafts with current driven, funnel shaped drums. The drums have helical fins inside very like transit mix cement truck bodies and turn about 8-10 rpm when lowered into the current. The drums have half inch or larger holes, so I suspect that they collect fish of reasonable size/maturity. At times, the drum is pivitoted upward out of the water on a hinge at the down stream end of the axis. The drum is about 6 feet in diameter at the upstream end, the raft roughly 8 16 feet.
What is it???
