IN SITU EXPERIMENTS WITH COASTAL PELAGIC FISHES 

 TO ESTABLISH DESIGN CRITERIA FOR ELECTRICAL FISH 



HARVESTING SYSTEMS^ 



WiLBER R. Seidel^ and Edward F. Klima^ 



ABSTRACT 



In situ experiments to test the efficacy of a scale electrical harvesting system were conducted off 

 Panama City, Fla. with both captured and wild coastal pelagic fishes. Six species of fish were 

 exposed to preselected combinations of pulse rate, pulse width, and voltage by either attracting 

 wild fish or placing captured fish between electrodes. Both captured and wild fish could be 

 effectively controlled with a minimum field strength of 15 V/m, 20 to 35 pulses/s, and a pulse width 

 of more than 0.5 ms. Voltage, pulse width, and pulse rate were equally important for controlling the 

 species tested. Based on these results, resistance measurements were calculated and a potential 

 netless harvesting system specified which would require a minimum energy output of 120 kVA 

 dissipated into an electrode configuration 10 x 5 x 5 m with a load resistance of 0.01558 ohms. 

 The basic design specifications for a prototype pulse generator are provided for netless fish 

 harvesting applications and mid- water trawling. 



Commercial fishing for the small, fast-swimming 

 fish schools characterizing much of the pelagic 

 fishery resource in the Gulf of Mexico has been 

 hampered due to a lack in harvesting technology 

 (Bulhs and Thompson, 1970). The Southeast 

 Fisheries Center, Pascagoula Laboratory, Na- 

 tional Marine Fisheries Service has been engaged 

 in the design and development of an electrical 

 harvesting system capable of economically exploit- 

 ing this resource. Results from laboratory experi- 

 ments (Klima, 1972) provided design criteria for 

 a 12-kVA (kilovolt ampere) pulse generator which 

 was used to field test and validate the electrical 

 control parameters and to provide design criteria 

 for a pulse generator capable of commercially 

 harvesting marine fishes from the Gulf of Mexico. 

 This paper describes the results of the electrical 

 in situ experiments using captured and wild fish. 

 Fishing with electricity was first used in fresh 

 water during the latter part of the 19th century by 

 Ishan Baggs, who was granted a British patent in 

 1863. Electrical fishing remained in obscurity 

 until after World War I, when McMillan (1928) 



'Contribution No. 249, Southeast Fisheries Center, Pas- 

 cagoula Laboratory, National Marine Fisheries Service. 



^Southeast Fisheries Center, National Marine Fisheries 

 Service, NOAA, P.O. Drawer 1207, Pascagoula, MS 39567. 



^Southeast Fisheries Center, National Marine Fisheries 

 Service, NOAA, Pascagoula; present address: Plans and Policy 

 Development Staff, National Marine Fisheries Service, NOAA, 

 Washington, DC 20235. 



began to use electricity to systematically guide 

 and lead fish. The use of electrical fishing in the 

 sea has lagged considerably behind that in fresh 

 water because of the high conductivity of salt 

 water, which results in extremely low load 

 resistance and therefore very high current and 

 power requirements for generation of significant 

 field strengths. Kreutzer (1964) showed pulsed 

 direct current could be utilized economically to 

 harvest fish in the sea provided that the field 

 voltage gradient and shape, duration, and rate of 

 impulses are suitable. Electrical stimulation 

 produces either fright, taxis, tetanus, or even- 

 tually death, depending upon the electrical field 

 pulse characteristics (Viber, 1967; Halsband, 

 1967; Lamarque, 1967). 



The reaction to various combinations of char- 

 acteristics varies with species, fish size, and 

 probably other factors (Riedel, 1952; Collins, 

 Volz, and Trefethen, 1954; Bary, 1956; Higman, 

 1956; Monan and Engstrom, 1963; Kessler, 1965; 

 Halsband, 1967; Klima, 1968); hence, a combina- 

 tion of electrical factors which will induce 

 electrotaxis in one species may induce a fright 

 response or no response in another. As a result, 

 it is critical to know the combination of electrical 

 field characteristics which will produce the de- 

 sired reaction for each species of interest. 



Success of electrical fishing equipment depends 

 upon use of optimum electrical combinations for 



Manuscript accepted November 1973. 

 FISHERY BULLETIN: VOL. 72, NO. 3, 1974. 



657 



