7784

• UCREFRP Catalog Number: 7784
• Author: Snyder, D. E.
• Title: Impacts of Electrofishing on Fish.
• USFW Year: 1992.
• USFW - Doc Type: \
• Copyright Material: NO

LIST OF TABLES

Table 1. Reactions identified in homogeneous
fields of direct current . . .. .......... 22

Table 2. Ranges of voltage-gradient (V/cm)
response thresholds . . .. ............ 24

Table 3. Summary of electrofishing mortality
and injuries . . . . . . . . . . . . . . . . . . . .. 32

Table 4. Procedures and criteria for
documenting damage to the spine. . .. .. 58

LIST OF FIGURES

Figure 1. Electrofishing-induced injuries to the
spine and associated hemonhages . . .. ., 2

Figure 2. Bent back in rainbow trout caused
by electrofishing. . . . . . . . . . . . . . . . ., 6

Figure 3. Bent backs and abnonnal growth in
westslope cutthroat trout . . .. ........ 7

Figure 4. Brands (bruises) in rainbow trout
caused by electrofishing. ............ 8

Figure 5. Changes in voltage gradient and
current density relative to water
conductivity . . .. ................. 10

Figure 6. Changes in current density and
power pensity relative to voltage
gradient . . .. .................... 11

Figure 7. Hypothetical two-dimensional maps
of heterogeneous electric fields . . . . 12

Figure 8. Distortion of electrical fields around
fish in water . . .. ................. 14

Figure 9. Selected wavefonns used in
electrofishing. .................... 16

Figure 10. Major intensity-dependent
electrofishing responses zones. ........ 20

Figure 11. Peak-voltage-gradient thresholds
for narcosis in 6- to 9-cm goldfish . . .. . 26

Figure 12. Peak-power-density thresholds for
narcosis in 6- to 9-cm goldfish . . .. .... 27

Figure 13. Dorsal-view and lateral-view X
rays of the same spinal misalignment. . .. 52

Figure 14. Hemonhage and associated tissue
and vertebral damage . . . as revealed by
necropsy. ........................ 53

Figure 15. Fractured vertebrae from an
electrofished rainbow trout. .......... 54

Figure 16. X rays of spinal anomalies in
rainbow trout. .................... 56

LIST OF APPENDICES

Appendix I. Indexed Bibliography of
Electrofishing Literature. .... iv + 57 pages

Appendix n. Requests for Infonnation and
Surveys on Electrofishing. ........ 3 pages

Appendix m. Threshold Values of Field Intensity
for Characteristic Reactions. ....... 7 pages

iv

Appendix IV. Aftereffects of Electric Fields on
Fish. . . . . . . . . . . . . . . . . . . . . . . . 3 pages

Appendix V. U.S. Fish and Wildlife Service. . .
Requirements . . . Guidelines . . .. . 16 pages

Appendix VI. Suggestions for Future Development
of Boat Electrofishing Gear . . .. .., 4 pages

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