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Wider Application of the Electrical Method of Collecting Fish
Author(s) -
Funk John L.
Publication year - 1949
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1577/1548-8659(1947)77[49:waotem]2.0.co;2
Subject(s) - streams , fish <actinopterygii> , environmental science , current (fluid) , population , computer science , fishery , electrical engineering , biology , engineering , computer network , demography , sociology
Limitations of the electrical‐shock method of collecting fish, as commonly used, are reviewed. Among these are the facts that the equipment considered necessary is cumbersome and costly; that the method is effective only on quite narrow, clear‐water streams; that effectiveness varies greatly with chemical content of soil and water; and that it is dangerous. Equipment and techniques that overcome these limitations to a greater or lesser extent are described. It has been found that less and more simple gear can be used effectively and safely. Methods of handling equipment which eliminate many time‐consuming delays have been developed. Equipment and procedures which are fully satisfactory on wider streams and in turbid waters are described. An electric “seine,” effective in streams 90 to 100 feet wide, has been developed. By employing special techniques, it can be used quite effectively in wider streams. In turbid water the method is less efficient but quite satisfactory sampling of the fish population can be made. Preliminary experiments have been made on the amount of electric current needed to stun fish without killing them. Apparently, most species of fish will be stunned but will recover in a few minutes from shock caused by 5 to 6 amperes of alternating current at 110 volts. Larger fish seem to be stunned more readily than those of fingerling size. Experiments on the efficiency of the method have been started. Factors influencing efficiency are believed to be chiefly those related to the recovery of stunned fish. Turbid water, swift current, and rough bottom all seem to decrease efficiency. Experimental evidence to confirm these beliefs is incomplete and inconclusive but it is evident that the method is highly effective in sampling qualitatively areas which otherwise could not be worked.