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Introduction to Electrofishing

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1 Introduction to Electrofishing
Lisa Harlan Smith-Root, Inc.

2 Outline Electrical Theory Electrofishing Equipment
Operation and Safety Applied Electrofishing Methods Written Exam

3 “What is electrofishing?”
The use of electricity to capture, guide, and block the movement of fish. An effective biological sampling tool. When done correctly injury to fish is minimal. This requires knowledge.

4 History of Electrofishing
Started in the late nineteenth century. Became fishery science tool in 1950’s and 60’s. Technology and knowledge have improved over the years. There are still many unknowns.

5 “Why is it Important to be Knowledgeable?”
Electrofishers have enough power to kill you. How many people have been shocked before? Electrofishers have enough power to kill fish. How many people have seen injured fish before?

6 What is electricity? The presence or movement of free electrons.
Protons, electrons, and ions Electrofishing is concerned with electrons and ions.

7 Current “Free electrons” - flow easily from one ion to another.
6.3 x 1018 electrons/sec = 1 Amp Amperes or Amps - flow of electric current.

8 Conductors, Insulators, Semi-conductors
Conductors - Lots of free electrons Metals, particularly Copper Stainless Steel Aluminum

9 Conductors, Insulators, Semi-conductors, cont.
Insulators - Substances with very few free electrons, flow of electrons is slow and arduous. Rubber Dry air Glass Fiber-reinforced plastics Distilled water

10 Conductors, Insulators, Semi-conductors, cont.
Semi-conductors - Substances that are in-between conductors and insulators. Silicon Sea water Rain water City water Germanium Silicon and Germanium used in diodes and transistors.

11 Why is this important? You need to know where the electricity will flow and where it won’t flow.

12 Basic Electrical Theory
Amperage - current, flow of free electrons Voltage - electrical pressure Resistance - amount of blockage or drag resisting the current Conductivity - the inverse of resistance

13 Ohm’s Law Calculates for Current (Amps).
Voltage = Current / Conductivity Current = Conductivity * Voltage Conductivity = Current / Voltage Note* Conductivity is the inverse of resistance. Ohms Law is V=I*R “Conductivity” is measured in uS. “Specific Conductivity” is measured in uS/cm.

14 Watt’s Law Calculates for Power (watts).
Power (watts) = Voltage * Current and Ohm’s Law states Current = Voltage * Conductivity therefore Power = Voltage * Voltage * Conductivity (AMP). A unit of electrical current or the rate of flow of electrons through a conductor. One volt across one ohm of resistance causes a current flow of one ampere. One ampere equals 6.25 x 1018 electrons per second passing a given point in a circuit; abbreviated amp. For example, a 1,200 watt, 120-volt hair dryer pulls 10 amps of electric current (watts divided by volts).

15 Main Components of the Electrofisher
Power Source Control Unit Electrodes

16 Control Units Backpack Boat

17 Boat Electrodes Anode Cathode

18 Backpack / Shore-based Electrodes
Anodes Cathodes

19 Power Sources Direct Current Alternating Current

20 Voltage The amplitude (or height) of the waveform. Measured in volts.
E.g. 120V

21 Types of Electrical Waveforms
AC DC Pulsed DC Burst of Pulses Pros and Cons Catches a lot of fish Easy to produce Low power loss High level of injury Catches fewer fish Easy to produce High power requirement Low level of injury Catches many fish Hard to produce Mod. power requirement Intermediate level of injury Catches many fish Hard to produce Low power requirement Indications are low level of injury

22 Pulse Period The duration of time for one complete cycle.
A cycle is measured from the start of one pulse to the start of the next pulse. Measurement includes both “on” and “off” times.

23 Frequency The number of pulse periods per second (hertz or Hz.).
The inverse of pulse period. 1/pulse period

24 Pulse Width The duration of “on” time within one pulse period.

25 % Duty Cycle The percentage of “on” time within one pulse period.
Pulse Width Pulse Period * 100% = % Duty Cycle Note* Frequency & Percent Duty Cycle has more effect on fish behavior AND fish injury. So use of minimal settings and proper technique is paramount. 20 ms 40 ms * 100% = 50% Duty Cycle

26 How do these things affect fish ?
Standard Pulse Waveform DEFINITIONS Pulse width : The length of time the current is ON period width Frequency : Number of pulses in a second volts How do these things affect fish ? time

27 a b 1 3 5 Exploring the Effects on Fish NOTE: volts The shorter
Pulse width : The length of time the current is ON The shorter the on-time, the less power you put into the water and into the fish NOTE: volts b 1 3 5 Time (ms)

28 a b 1 3 5 Exploring the Effects on Fish NOTE: volts The fewer the
Frequency (Hz): Number of pulses per second a The fewer the pulses, the better. Frequency is a major factor in fish injury !! NOTE: volts b 1 3 5 Time (ms)

29 To minimize fish injury: use lowest pulse width and frequency
Time (ms) 5 1 3 on off

30 “Duty-cycle” is the percent of on-time

31 Duty-cycle = “pulse width” X “pulse frequency” (divided by 10)
Example: Pulse width = 4 ms Frequency = 20 Hz Duty-cycle = (4 x 20)/10 = 8%

32 Duty-cycle = (4 x 20)/10 = 8% Duty-cycle = 24% Pulse width = 4 ms
Frequency = 20 Hz Pulse width Frequency Duty-cycle = (4 x 20)/10 = 8% Duty-cycle = 24%

33 Electric Field Intense near electrodes Dissipates with distance
Reynolds, 1996

34 Power Density Power Density = Voltage Gradient * Current Density
Power = Voltage * Voltage * Conductivity *Note voltage gradient (v/cm) and current density (A/cm2) as well as water conductivity (uS/cm). V/cm*A/cm2= watts/cm3. Sort of combining of Ohm’s Law and Watt’s Law Based on Volume. *Note quadrupling effect on Power Density when voltage is doubled.

35 Specific Water Conductivity

36 Conductivity of Water Low Conductivity < 100 S/cm
Requires higher voltage. High conductivity > 1, S/cm Requires high current. Power requirement lessens as the conductivity of the water matches the conductivity of the fish. Conductivity of the water and fish increase as temperature increases.

37 Power Transfer Theory Use “behavior” of electrical current to explain this interaction. Reynolds, 1996

38 Review How do changes in water conductivity affect power requirements?
How do changes in fish conductivity affect power requirements?

39 Electrofishing Equipment
There are a variety of electrofishers systems out there…

40 Backpack electrofishing

41 Tote-barge electrofishing

42 Boat electrofishing

43 Main Components of the Electrofishing System
Control Unit Power Source Electrodes

44 Power Sources Battery Generator

45 Function of Control Units
Accepts input from power source Controls and allows control of the output Instrumentation monitors input and output Has power on/power off control Has connectors for anode and cathode Timers to measure electrofishing time

46 2.5, 5.0, 7.5, 9.0 GPP Electrofishers Produces pulsed forms of AC and DC. AC at 60Hz, DC at 7.5, 15, 30, 60 and 120 Hz. Control of pulse width and frequency on DC.

47 VVP - 15B Electrofisher Produces DC, pulsed DC and AC.
Pulsed DC- Freq Hz, Duty cycle 10-80%. Burst of Pulses - groups of 3 or 6 at Hz. AC - 60 Hz. Will Service Coffelt Products Except MK-10 & MK-18 (backpack shockers) MK-50-B (Boat/Shore unit)

48 LR-24 Electrofisher Produces DC, pulsed DC, and Burst of Pulses.
Pulsed DC - Freq Hz, Duty cycle %. Burst of Pulses Hz

49 Electrodes - Backpack and Shore-based
Anodes Cathodes

50 Boat Electrodes Anode Cathode

51 Important Electrode Parameters
Size Shape Condition Orientation

52 Anode Size Reynolds, 1996

53 Cathode Size The cathode should have ~3 times the surface area as the anode. The larger surface area decreases the electric field intensity near the cathode.

54 Electrode Shape The electric field is affected by the shape of the electrode. Show examples on white board.(Ask Rick)

55 Electrode Condition Electrolysis of the aluminum occurs over time creating a hard ceramic insulating surface. Aluminum electrodes need to be cleaned regularly. Netting impedes cleaning (and…). Stainless steel electrodes do not oxidize. Stainless steel will eventually rust due to the fact that the nickel content gets “zapped” out of it from electricity being run though it (aka: electrolysis).

56 Electrode Orientation
The electric field is affected by the position of the electrodes in relation to each other. The closer they are together the more intense the field.

57 Four Behavioral Zones Fright Zone Taxis Zone Tetanus Zone Kill Zone
Note that not all “zones” are equally spaced away from anode. Site specific changes in electric field (voltage, electrode issues, conductivity, fish orientation, etc.).

58 Fish Behavior Definitions
Fright/Escape: fish swim away Taxis: Fish swims toward anode Tetany/Narcosis: fish immobilized Kill

59 Like a puppet on a a string!
This is taxis. Lead fish to netters. Increase efficiency. Decrease injury Ready to net that fish… No.

60 Fish Injury What are the potential injuries to fish?
How can I tell if fish are being injured? What can I do to reduce fish injury?

61 Potential Fish Injuries
Stress Syndrome Hemorrhaging Vertebral Injury Death Egg Viability and Reproductivity

62 Stress Syndrome Physiological and behavioral changes
Acidosis and reduced respiratory efficiency Can take hours to days to recover If death occurs, it’s usually within a few hours, and is respiratory failure.

63 Fish Hemorrhaging Level Two Level Three
Represents ONE actual hemorrhage. Level Three

64 External “Branding” Caused by capillaries under skin hemorrhaging.
Usually chevron-shaped. Can be long-lasting and be a site for infection. Likely has internal injuries as well. Unbruised fish might also have internal injuries. Dark splotches can appear which are not bruising and will disappear in a short time.

65 Vertebral Injury

66 Injuries to Fish Fisheries Techniques, Chp 8 Slideshow

67 Death of Fish Egg Viability and Reproductivity
Consider filleting dead fish to look for hemorrhaging. Fillet along both sides of spine, looking for bloody spots near spine corresponding to spots on fillet. Egg Viability and Reproductivity Not much is known about the effects of electrofishing in this area. Avoid spawning females and active spawning areas.

68 Factors that Affect Fish Injury
1. Settings on the Electrofisher 2. Equipment Choices 3. Electrofishing Technique

69 Setting Up the Electrofisher
Know conductivity of the water. Select a waveform. Set a voltage. Select a frequency. Select the pulse width (or duty cycle)

70 Conductivity of Water Low Conductivity < 100 S/cm
Requires higher voltage. High conductivity > 1, S/cm Requires high current. Power requirement lessens as the conductivity of the water matches the conductivity of the fish. Conductivity of the water and fish increase as temperature increases.

71 Types of Electrical Waveforms
AC DC Pulsed DC Burst of Pulses Pros and Cons Catches a lot of fish Easy to produce Low power loss High level of injury Catches fewer fish Easy to produce High power requirement Low level of injury Catches many fish Hard to produce Mod. power requirement Intermediate level of injury Catches many fish Hard to produce Low power requirement Indications are low level of injury

72 “What Settings Should I Use?”
Use the lowest voltage, frequency, and duty cycle combination that elicits “taxis” but minimizes “tetanus”.

73 If fish twitches and escapes, voltage is high enough!
Step 1: Volts Need enough volts to get fish to twitch. If fish twitches and escapes, voltage is high enough! USFS,Boise ID

74 power density quadruples.
A note about voltage…. Power density = (Volts/cm)2 x conductivity If you double voltage, power density quadruples.

75 Hemorrhage Data Unpublished Data: Do Not Cite

76 Vertebral Injury Data Unpublished Data: Do Not Cite

77 Behavior and Vertebral Damage (Frequency)
Unpublished Data: Do Not Cite

78 % of Marked Fish Showing Vertebral Damage
Unpublished Data; Do Not Cite

79 Equipment Choices Electrodes: size, shape, condition, orientation Dip Nets: shape, depth and mesh size Electrofisher: appropriate one for the conditions

80 Electrofishing Technique
Minimize fish exposure time to electric field. Keep distance between electrode & fish consistent (if possible). Be quick about netting the fish. “Hey Buddy! Don’t break a sweat!”

81 Electrofishing Technique, cont.
What would you change? Resist “pointing” with anode. Reduce exposure. Site variables? “Hey! That was my fish!”

82 What would you change? Safety first. Water level/velocity.
Position of netters. Differences in netting techniques. Levels of efficiency. How deep is still safe?

83 Care of Fish Remove fish immediately from electrical field and into holding buckets. Avoid netting rocks also. Refresh water frequently or use an aerator. Work up fish often. If holding fish in netted area make sure they are always out of electrical field after capture.

84 “What should I do if I observe fish with external marking?”
First, evaluate your technique. Make adjustments accordingly. Second, evaluate your settings. Reduce frequency. Reduce duty cycle. Reduce voltage.

85 Review List the 3 main components of an electrofisher.
How does electrode size affect the electric field? What are the potential injuries to fish? How should you set up an electrofisher?

86 “Why Should I Bother With Safety?”
All electrofishers have enough power to kill humans.

87 Effects of Electrical Current on the Human Body
1 milliamp Just a faint tingle. 5 milliamps Slight shock felt. Disturbing, but not painful. Most people can “let go”. However, strong involuntary movements can cause injuries. 6-25 milliamps (women) 9-30 milliamps (men) Painful shock. Muscular control is lost. This is the range where “freezing currents” start. It may not be possible to “let go”. milliamps Extremely painful shock, respiratory arrest (breathing stops), severe muscle contractions. Flexor muscles may cause holding on; extensor muscles may cause intense pushing away. Death is possible. 1,000-4,300 milliamps ( amps) Ventricular fibrillation (heart pumping action not rhythmic) occurs. Muscles contract; nerve damage occurs. Death is likely. 10,000 milliamps (10 amps) Cardiac arrest and severe burns occur. Death is probable. *Effects are for voltages less than about 600 volts. Higher voltages also cause severe burns. *Differences in muscle and fat content affect severity of shock. Centers for Disease Control and Prevention, 2002

88 Life-threatening Condition
Cardiac Arrest Ventricular Fibrillation Respiratory Arrest Lactic Acidosis (delayed onset)

89 “How Do I Electrofish Safely?”
Training Proper Equipment Crew Preparation Emergency Planning Operational Safety

90 Training Minimum of two crew members trained in First Aid/CPR particularly as applied to electric shock. Crew leader, at a minimum, has taken an Electrofishing Course.

91 Proper Equipment - Personal Protection Equipment
Required Non-breathable Waders or Hip Boots. Non-slip Boots Lineman’s Gloves Optional PFD or Wading Belt Brimmed Hat Polarized Sunglasses

92 Proper Equipment - Backpack Electrofisher
Tilt Switch Anode Pole (Power Output) Switch Audible Signal Quick Release Harness Emergency Kill Switch

93 Additional Backpack Electrofisher Safety Features
Immersion Sensor Electrode Out of Water Sensor Visual Signal (Red Flashing Light)

94 Proper Equipment - Fully Functional
Inspect equipment before every use. Don’t work with faulty or malfunctioning electrofishing equipment. Damaged curl cord. Damaged connectors. Broken anode pole switch. Damage strain relief (top of pole). Dead/broken battery or out of gas.

95 Crew Preparation Maintain a crew size of at least 3 preferably 4 people (at least 4 people for shore-based electrofishers). Have an assigned crew leader. Clarify crew leader responsibilities. Clarify crew responsibilities.

96 Crew Preparation - Crew Leader Responsibilities
Ensure overall crew safety, meet sampling objectives, and monitor welfare of the fish. Brief all crew on basics of electrofishing, including dangers and safety requirements. Have emergency plan in place and communicate it to all crew members. Nearest hospital and quickest route to it. Location of vehicle keys, cell phones, radios and how to operate them. Crew leader is only person to order power on. Ensure all crew knows anyone can order power off.

97 Crew Preparation - Crew Responsibilities
Be trained in basics of electrofishing and safe electrofishing practices. Be aware of nearest hospital, evacuation route, location of vehicle keys, cell phones, and radios and know how to operate them. Be alert and attentive, take breaks as necessary. Communicate with rest of crew. Do not electrofish if you have heart ailments, wear a pacemaker, or are pregnant.

98 Crew Preparation - Crew Communication
Effective communication between crew members is essential. Be sure you know the plan before the electrodes are energized. If working in noisy conditions utilize hand signals. Standardized “Power On” and “Power Off” Signals. Power On: Patting hand on top of head with announcement. Power Off: Slicing the hand across the throat with announcement. Hand signals and announcements confirmed by everyone.

99 Emergency Planning Prepare and have a plan ahead of time.
Always carry First Aid kit. In case of accident: Turn off power to electrofisher and remove it from the situation. Evaluate situation and take appropriate action. If a person has been shocked they need to go immediately to nearest hospital.

100 Operational Safety Never electrofish alone. Minimum of three person crew. Remove chest strap before entering water. Shut off power before entering or leaving water. Be sure all crew members are clear of electrodes before turning power on and before energizing electrodes. Do not touch electrodes when power is on, not even while wearing Lineman’s gloves. Turn electrofisher off before connecting or replacing parts.

101 Operational Safety, cont.
Operate slowly and carefully to prevent slips and falls. Electrofish only as far as you can safely wade. Never electrofish with spectators on shore. Stop electrofishing immediately if water gets in waders, hip boots, or gloves. Do not resume electrofishing until completely dry.

102 Crew Safety Accidents happen Be prepared for the worst
Safety equipment Safety procedures

103 Crew Safety - Things to Avoid
Don’t become the conductor. Don’t touch anything in the surroundings. Don’t touch the electrodes. Don’t use uninsulated dip net handles. Don’t work without properly fitting/fully functional personal safety equipment.

104 Review What are the responsibilities of the crew leader?
How do you electrofish safely?

105 Applied Electrofishing
Determine sampling parameters prior to electrofishing: Objectives Amount of effort - distance, time, or sample size. “Consistency and objectivity”

106 Factors that affect Sampling Efficiency
Electrodes Water/ Environmental Conditions Equipment Settings/ Capabilities Fish Variables Human Components

107 Standardized sampling guidelines
Collect all fish possible to avoid bias Standardize voltage output Pulse rate = 5-40 Hz Duty cycle = 25% Standardize season - spring or fall Standardize the water stage in flowing water (not too high or low) Fisheries Techniques,Chp 8 slideshow

108 Lake and Pond Sampling Use boat electrofisher.
Spring and autumn are when adults tend to be close to shore. Night or twilight are when predators move inshore. Sample entire shoreline if possible. If not, more small samples better than few large samples.

109 Data analysis Species composition Species abundance
Population structure Population dynamics - catch curve/mark-recapture Species composition- will be successful with certain species,but not all. Watch for bias. Species abundance- CPUE very good when targeting specific age classes. Population structure - Length-frequency data should be regarded with caution. Electrofishing is size selective. Population dynamics - Very limited possibilites due to size selectivity of electrofishing.

110 Review Electrical Theory Electrofishing Equipment Operation and Safety
Applied Electrofishing Methods

111 Sources Department of Health and Human Services. Electrical Safety: Safety and Health for Electrical Trades Reynolds, James. Electrofishing. Pages B. R. Murphy and D. W. Willis, editors. Fisheries techniques, 2nd edition. American Fisheries Society, Bethesda, MD

112 Stream Sampling Backpack electrofishers good for small streams.
Shore-based or boats for larger streams. Flowing waters limit sampling due to safety issues. Boat-shock usually downstream, wade usually upstream. Sample streams methodically with randomness.

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