Electricity in Fish Research and Management

Acknowledgements, viii
1 Introduction, 1
2 The history of electricity in fish research, 3
3 Electric fishing, 7
3.1 Health and safety, 13
3.1.1 Electric shock, 14
3.1.2 Drowning, 16
3.1.3 Tripping or falling, 16
3.1.4 Trauma, 16
3.2 General issues, 16
4 Electrical terms, 17
4.1 Circuit, 19
4.2 Voltage, 19
4.2.1 Voltage gradient, 22
4.3 Voltage waveforms, 26
4.3.1 Alternating current, 27
4.3.2 Direct current, 28
4.3.3 Pulsed direct current, 30
4.3.3.1 Pulse frequency, 35
4.3.3.2 Pulse width, 38
4.4 Electrical current, 41
4.5 Power, 42
4.5.1 Power factor, 44
4.6 Resistance and resistivity, 44
4.6.1 Electrode resistance, 47
4.6.2 Kirchoff's Law, 49
4.7 Conductance and conductivity, 51
4.7.1 High?]conductivity water, 52
4.7.2 Low?]conductivity water, 52
4.8 Fish conductivity, 53
4.8.1 Water-fish conductivity ratio, 55
4.8.1.1 Graphic depiction, 57
4.8.1.2 Circuit theory, 57
4.8.1.3 Power Transfer Theory (PTT), 58
5 Electric fishing equipment, 63
5.1 Generators, 64
5.1.1 Use of multiple generators and control boxes, 65
5.2 Control boxes, 66
5.2.1 Generator?]based control boxes, 67
5.2.1.1 Control boxes with no facility to control output, 68
5.2.1.2 Control boxes with limited ability to control output, 68
5.2.1.3 Control boxes where many parameters of the output can be controlled, 70
5.2.2 Battery?]powered control boxes, 71
5.3 Electrodes, 72
5.3.1 Anodes, 73
5.3.1.1 Anode shape, 75
5.3.1.2 Anode size, 77
5.3.1.3 Twin and multiple anodes, 79
5.3.1.4 Anode ergonomics, 81
5.3.2 Pre?]positioned area samplers (PPAS), 82
5.3.3 Point abundance sampling using electricity (PASE), 83
5.3.4 Electric nets, 84
5.3.5 Cathodes, 85
5.4 Hand nets, 87
5.4.1 Banner nets, 90
5.5 Stop nets, 90
5.6 Protective and safety equipment, 92
5.6.1 Waders, 92
5.6.2 Gloves, 92
5.6.3 Other protective clothing, 93
5.6.4 Lifejackets, 93
6 Practical factors affecting electric fishing efficiency, 94
6.1 Manpower requirements, 94
6.2 Streambed: conductivity and substrate type, 95
6.3 Weather, 96
6.4 Water temperature, 96
6.5 Fish size, 97
6.6 Fish species, 98
6.7 Fish numbers, 99
6.8 Water clarity, 100
6.9 Site length, 100
6.10 Water depth, 101
6.11 Site width, 101
6.12 Time of day, 102
7 Electric fishing working techniques, 103
7.1 Operator skill and fishing and processing methods, 103
7.2 Fishing using wading, 106
7.2.1 Wading fishing using boats, 108
7.3 Fishing from boats, 110
7.3.1 Boom?]boats, 111
8 Electric fishing 'best' practice, 116
9 Fish population assessment methods, 122
9.1 Estimating relative abundance, 124
9.2 Estimating actual population size, 126
9.2.1 Capture-mark-recapture estimates (CMRs), 127
9.2.2 Catch depletion estimates, 128
10 Fish barriers, 132
11 Fish counters, 138
12 Electroanaesthesia, 142
13 Fish welfare, 145
13.1 Fish handling, 146
13.2 Stress, 146
13.3 Anaesthesia, 148
13.4 Fish density in holding bins, 151
13.5 Oxygen and carbon dioxide, 153
13.6 Ammonia, 154
13.7 Temperature, 155
13.8 Osmotic balance, 155
13.9 Sensitive or robust fish, 155
13.10 Fish eggs, 156
13.11 Bio?]security, 156
14 Record keeping required, 158
15 Summary, 159
Glossary, 161
References, 166