 Uganda Game and Fisheries Department (UGFD) officials denied that they were involved, but circumstantial evidence suggests otherwise and local Africans employed by UGFD have said that they introduced the species in 1954–55 under the directive of senior officials.UGFD officials argued that Nile perch must have spread to Lake Victoria by themselves by passing through the Owen Falls Dam when shut down for maintenance, but this is considered highly unlikely by many scientists.The Nile perch had spread throughout the lake by 1970.