Oregon Revised Statutes Commercial Fishing and Fisheries § 506.610

(1) The possession or custody of food fish on, near, adjacent to or in the vicinity of any waters of this state, during the closed season on such waters, is prima facie evidence that such fish were unlawfully taken during the closed season on such waters.

(2) In all cases where such possession or custody by accused persons on, near, adjacent to or in the vicinity of any of such closed waters is proven, the burden of proof is shifted to the persons found having such possession or custody, to establish that the fish were lawfully taken during an open season and from waters from which it was at such time lawful to take such fish.