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

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

2 Outline Electrical Theory Electrofishing Equipment Operation and Safety Applied Electrofishing Methods Written Exam 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. 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.  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? 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.  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 electrons/sec = 1 Amp Amperes or Amps - flow of electric current. “Free electrons” - flow easily from one ion to another. 6.3 x 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  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  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.  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 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 Voltage = Current / Conductivity Current = Conductivity * Voltage Conductivity = Current / Voltage

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 Power (watts) = Voltage * Current and Ohm’s Law states Current = Voltage * Conductivity therefore Power = Voltage * Voltage * Conductivity

15 Main Components of the Electrofisher 1.Power Source 2.Control Unit 3.Electrodes

16 Control Units Backpack Boat

17 Boat Electrodes Anode Cathode

18 Backpack / Shore-based Electrodes Anodes Cathodes

19 Power Sources Direct Current Direct Current Alternating Current Alternating Current

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

21 Catches a lot of fish Easy to produce Low power loss High level of injury Catches a lot of fish Easy to produce Low power loss High level of injury AC Catches fewer fish Easy to produce High power requirement Low level of injury Catches fewer fish Easy to produce High power requirement Low level of injury DC Catches many fish Hard to produce Mod. power requirement Intermediate level of injury Catches many fish Hard to produce Mod. power requirement Intermediate level of injury Pulsed DC Types of Electrical Waveforms Pros and Cons Burst of Pulses Catches many fishCatches many fish Hard to produceHard to produce Low power requirementLow power requirement Indications are low level of injuryIndications 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. 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 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 Pulse Width Pulse Period Pulse Width Pulse Period * 100% = % Duty Cycle 20 ms 40 ms 20 ms 40 ms * 100% = 50% Duty Cycle % Duty Cycle The percentage of “on” time within one pulse period.

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

27 Exploring the Effects on Fish Time (ms) volts 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: 5 a b 1 3

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

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

30 “Duty-cycle” is the percent of on-time “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 Pulse width Frequency Pulse width = 4 ms Frequency = 20 Hz Duty-cycle = (4 x 20)/10 = 8% Duty-cycle = 24%

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

34 Power Density Power Density = Voltage Gradient * Current Density Power = Voltage * Voltage * Conductivity

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. 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 Reynolds, 1996

38 Review How do changes in water conductivity affect power requirements? How do changes in fish conductivity affect power requirements? 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 1.Control Unit 2.Power Source 3.Electrodes

44 Power Sources BatteryGenerator

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.

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 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.

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. 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.

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. 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 1.Fright Zone 2.Taxis Zone 3.Tetanus Zone 4.Kill Zone

58 Fish Behavior Definitions  Fright/Escape: fish swim away  Taxis: Fish swims toward anode  Tetany/Narcosis: fish immobilized  Kill  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. 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?  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  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.  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 Level Two Level Three Fish Hemorrhaging

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.  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 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 1. Settings on the Electrofisher 2. Equipment Choices 3. Electrofishing Technique

69 Setting Up the Electrofisher 1.Know conductivity of the water. 2.Select a waveform. 3.Set a voltage. 4.Select a frequency. 5.Select the pulse width (or duty cycle) 1.Know conductivity of the water. 2.Select a waveform. 3.Set a voltage. 4.Select a frequency. 5.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. 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 Catches a lot of fish Easy to produce Low power loss High level of injury Catches a lot of fish Easy to produce Low power loss High level of injury AC Catches fewer fish Easy to produce High power requirement Low level of injury Catches fewer fish Easy to produce High power requirement Low level of injury DC Catches many fish Hard to produce Mod. power requirement Intermediate level of injury Catches many fish Hard to produce Mod. power requirement Intermediate level of injury Pulsed DC Types of Electrical Waveforms Pros and Cons Burst of Pulses Catches many fishCatches many fish Hard to produceHard to produce Low power requirementLow power requirement Indications are low level of injuryIndications 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 Step 1: Volts Need enough volts to get fish to twitch. If fish twitches and escapes, voltage is high enough! USFS,Boise ID

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

75 Unpublished Data: Do Not Cite Hemorrhage Data

76 Unpublished Data: Do Not Cite Vertebral Injury Data

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

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

79 Equipment Choices  Electrodes: size, shape, condition, orientation  Dip Nets: shape, depth and mesh size  Electrofisher: appropriate one for the conditions  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. 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? 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? 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.  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. Make adjustments accordingly. Reduce frequency. Reduce duty cycle. Reduce voltage. First, evaluate your technique. Make adjustments accordingly. Second, evaluate your settings. Make adjustments accordingly. 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? 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 milliampJust a faint tingle. 5 milliampsSlight shock felt. Disturbing, but not painful. Most people can “let go”. However, strong involuntary movements can cause injuries 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” milliampsExtremely 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. Centers for Disease Control and Prevention, 2002

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

89 “How Do I Electrofish Safely?” 1.Training 2.Proper Equipment 3.Crew Preparation 4.Emergency Planning 5.Operational Safety 1.Training 2.Proper Equipment 3.Crew Preparation 4.Emergency Planning 5.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.  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 1.Non-breathable Waders or Hip Boots. 2.Non-slip Boots 3.Lineman’s Gloves Optional 1.PFD or Wading Belt 2.Brimmed Hat 3.Polarized Sunglasses

92 Proper Equipment - Backpack Electrofisher Tilt Switch Anode Pole (Power Output) Switch Audible Signal Quick Release Harness Emergency Kill Switch 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) 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. 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. 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. 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.  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. 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. 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.  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.  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 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. 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? 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”  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 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)  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.  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  Species abundance  Population structure  Population dynamics - catch curve/mark-recapture

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