Proposal of a 'hot lock' as a barrier to fish invasion: an afterthought

Engineers may indeed prevail and a connection between the two river systems may be established. Some means, however, must be found to prevent invading fish species passing from one river to the other. The authors propose a barrier to fish movement in the form of a non-polluting lock of warmed water strategically placed in the canal system linking the two natural water-ways. Perusal of upper lethal temperature data of fish (Coutant 1973) reveals that temperatures slightly below 40 degree C are acutely lethal at brief exposure to most species. This temperature, one or two degrees over normal body temperature, does not pose a danger to humans. In addition, fish will display avoidance reactions to the two attenuated warm boundaries of the heated reach of the canal.