7123 (3) - Laserfiche WebLink

Home Browse Search

1610 JOURNAL FISHERIES RESEARCH BOARD OP CANADA, VOL. 29, NO. 11, 1972 2C K t ,< 3f 3 z t~ 7aenu. ~ -' a.5 von. P~ IthyOnN 711M 3.0 VoIL .~ _ ' 1.5 Volt. 1 I- ~ I.o vt, ~ ~--F -+ K c species were on the average longer than the round '° herring and silver anchovy. 1 was unable to capture ° specimens of a larger sire to confirm the above hypothesis. Presumably, larger round herring and silver anchovy would also require only 1.5 v/10 cm stimulation to induce electrotaxis. Inability to capture adequate quantities of live fish limited the experimental tests on the remaining ~° species. The most suitable combinations to induce ° electrotaxis appeared to be 1.5 v/10 cm at 15 pulses/ sec for chub mackerel (Table 4), bumper (Fig. 5), and thread herring (Table 5); and 1.5 v/10 cm at 15-25 pulses/sec for round scad (Table 5) and rough scad (Fig. 6). A 0 It. 50 55 O D ~° ~~ p, J W O 2 0 I- a F t° ~ 0 I 00 so 5 O 15 25 35 +5 55 65 +.5 vat. IC 5 c 3.0 Von. li t 5 t t 1.5 Volt. > t Lo vat. 0 0 +.° Vull. ,° _ -0 Ioc p- . - -o. - 10 ~, ,O ~ ~~ o ° 3.0 Volic .o -o- - la ,v--- --v .' 10 ~ 5( ~~ 0 0 1.5 Volt. 20 10 10 ~ 51 _. o ~ ° ~s a5 55 V ,/ •PUISES / SEG Fishing Applications Fishing systems which attract and concentrate fish could use electricity to lead fish to the anode for economical extraction with pumps. Preliminary in- formation is provided on an electrode configuration and its power requirements. This electrode type, when used with lights•and pumps, should be suitable for commercial harvesting of coastal pelagic fishes in many areas of the world. Guiding or leading coastal pelagic and bottom fish to the anode is most easily accomplished within a uniform electric field. Nonuniform fields, as the name implies, have a gradation of voltage which increases as the fish approach the anode. Thus, fish at the outer edge of a nonuniform electric field undergo a fright reaction because of the low voltage gradient. Fish in the center of the field undergo electrotaxis and swim toward the anode until the voltage drop is sufficient to cause tetanus. Fright and tetanus responses are undesirable for leading fish. 1n a uniform field, however, fish can be led considerable distances to the anode without a tetanus reaction. An ideal fishing situation can be established, therefore, with a uniform electric field combining the proper parameters. The results of this study have been used to cal- culate the power requirements for field electrodes for a harvesting system. The parameters used were I5-30 v/m at pulse rates ranging from 15 to 45, with a capacitor discharge pulse shape at a pulse width of 1.0 msec. It was assumed that this system would operate in sea water with a salinity of 30%0, a temperature of 25 C, and a resistivity of 0.213 ohm-meters (Myers et al. 1969). This configuration should provide approximate uniform fields between Flc. 2. Times to swim one lap (solid lines), percent in tetanus (broken lines) at end of one lap, and optimal response indexes at various pulse rases and voltages for longspine porgy, silver anchovy, and spot. Each plotted value is for an initial loC of 10-31 fish. 4 1 i 1