A Modification of the Electric Fish Shocker for Lake Work

stunning fish was demonstrated almost two decades ago in Europe (Hager, 1934), but only during the past ten years have American biologists developed the for their particular needs. This device has been used principally in population studies of small streams, especially the trout streams of northern and north-eastern United States. In Illinois and other states throughout the mid-west and south, artificial impoundments support an important part of the sport fishery. Securing live specimens for food habit studies or marking, from the shallow weed or stump-filled waters of these areas, presents a difficult problem. A search for an efficient collecting method led us to modify the fish shocker for use from a rowboat. This development of the electric shocker provides a labor-saving means of sampling lake populations in areas where seining and wading are impossible. An old abandoned strip-mine, lying in the flood plain of the Middle Fork River in east-central Illinois and supporting a large and varied fish population, has been the principal site for testing the rowboat shocker. When strip-mining for coal was discontinued in this area and the deep channels between spoil banks filled with water, a private fishing club purchased the mine properties. Flood water from the Middle Fork has reduced the acid from