If the lack of OXYGEN is killing fish, We may want to think about removing fish(if we find any) from to area we catch them, likely there is OXYGEN there and not any or enough where we release them ! Stress may be a factor in this case as well. As Fishermen,Sportsmen,(as well as LADIES),and Conservations we all want the Rivers to Recover as quickly as possible from what ever is killing our fish, Maybe think about trying other Rivers,Lakes, Ponds this may help give these Rivers a little help in the recover ! This is just something to THINK about ! Andfor a fast recover !