ABSTRACT
The catadromous fish are mainly eels, freshwater mullet of southern Africa, golden perch, and Australian bass. These fish are for the most part faced with low dams in Europe, and Australia, so that there is no great problem involved in their traveling downstream when they mature. Downstream passage over low weirs does not present a hazard. The fish losses due to hydroelectric plants vary according to the route taken by the fish on their journey downstream. It has been found that the best way to reduce fish mortality in existing installations is to operate them at maximum efficiency during the period of downstream migration. At downstream barriers, fish that enter the electrified field too deeply become narcotized and are carried by the even deeper into the electrical field, from which there is little hope of escape. On the West Coast of North America, partial screens have been tested and found satisfactory for diverting many of the migrant to safe passages.
