introduction to electrofishing lisa harlan smith-root, inc. lisa harlan smith-root, inc

Introduction to ElectrofishingIntroduction to Electrofishing

Lisa HarlanSmith-Root, Inc.

OutlineOutline

• Electrical Theory• Electrofishing Equipment• Operation and Safety• Applied Electrofishing Methods• Written Exam

“What is electrofishing?”“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.

History of ElectrofishingHistory 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.

“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?

What is electricity?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.

CurrentCurrent

“Free electrons” - flow easily from one ion to another.

6.3 x 1018 electrons/sec = 1 Amp

Amperes or Amps - flow of electric 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.

Conductors, Insulators, Semi-conductors

Conductors - Lots of free electronsMetals, particularlyCopperStainless SteelAluminum

Conductors, Insulators, Semi-conductors, cont.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

Conductors, Insulators, Semi-conductors, cont.Conductors, Insulators, Semi-conductors, cont.

Semi-conductors - Substances that are in-between conductors and insulators.

SiliconSea waterRain waterCity waterGermanium

Silicon and Germanium used in diodes and transistors.

Semi-conductors - Substances that are in-between conductors and insulators.

SiliconSea waterRain waterCity waterGermanium

Silicon and Germanium used in diodes and transistors.

Why is this important?Why is this important?

You need to know where the electricity will flow and

where it won’t flow.

You need to know where the electricity will flow and

where it won’t flow.

Basic Electrical TheoryBasic 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

Ohm’s LawCalculates for Current (Amps).

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Voltage = Current / ConductivityCurrent = Conductivity * VoltageConductivity = Current / Voltage

Watt’s Law Calculates for Power (watts).

Power (watts) = Voltage * Current

and Ohm’s Law states

Current = Voltage * Conductivity

thereforePower = Voltage * Voltage * Conductivity

Power (watts) = Voltage * Current

and Ohm’s Law states

Current = Voltage * Conductivity

thereforePower = Voltage * Voltage * Conductivity

Main Components of the Electrofisher

1. Power Source2. Control Unit3. Electrodes

Control UnitsControl Units

QuickTime™ and aTIFF (LZW) decompressor

BackpackBackpack BoatBoat

Boat ElectrodesBoat Electrodes

AnodeAnode

CathodeCathode

Backpack / Shore-based Electrodes

AnodesAnodes

Cathodes Cathodes

Power SourcesPower Sources

DirectCurrentDirect

Current QuickTime™ and aTIFF (Uncompressed) decompressor

AlternatingCurrent

VoltageVoltage

• 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

• Catches a lot of fish

• Easy to produce

• Low power loss• High level of

injury

• Easy to produce

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

Pulsed DC

Types of Electrical Waveforms

Pros and ConsPros and Cons

Burst of Pulses

• Hard to produce• Low power

requirement• Indications are

low level of injury

Pulse PeriodPulse 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.

FrequencyFrequency

• 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

Pulse WidthPulse Width

• The duration of “on” time within one pulse period.

Pulse WidthPulse PeriodPulse WidthPulse Period

* 100% = % Duty Cycle* 100% = % Duty Cycle

20 ms40 ms20 ms40 ms

* 100% = * 100% = 50% Duty Cycle50% Duty Cycle

% Duty Cycle% Duty Cycle

The percentage of “on” time within one pulse period.

Standard Pulse WaveformStandard Pulse Waveform

period

DEFINITIONS

Pulse width :The length of timethe current is ON

Frequency :Number of pulsesin a second

How do these things affect fish ?

Exploring the Effects on FishExploring the Effects on Fish

Time (ms)

Pulse width :The length of timethe current is ON

The shorterthe on-time, the less poweryou put into the water andinto the fish

Exploring the Effects on FishExploring the Effects on Fish

Time (ms)

voltsThe fewer thepulses, the

better.Frequency isa major factorin fish injury !!

Frequency (Hz):Number of pulsesper second

To minimize fish injury:

use lowest pulse width and frequency

To minimize fish injury:

use lowest pulse width and frequency

Time (ms)

off off

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

Duty-cycle =

“pulse width” X “pulse frequency” (divided by 10)

Duty-cycle =

“pulse width” X “pulse frequency” (divided by 10)

Example:

Pulse width = 4 msFrequency = 20 Hz

Duty-cycle = (4 x 20)/10 = 8%

Pulse width

Frequency

Pulse width = 4 msFrequency = 20 Hz

Duty-cycle = (4 x 20)/10 = 8%

Duty-cycle = 24%

Electric FieldElectric Field

Reynolds, 1996

• Intense near electrodes

• Dissipates with distance

Power DensityPower Density

Power Density = Voltage Gradient * Current Density

Power = Voltage * Voltage * Conductivity

Specific Water Conductivity

Conductivity of WaterConductivity of Water

Low Conductivity < 100 S/cm Requires higher voltage.

High conductivity > 1,500 - 2000 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.

Power Transfer TheoryPower Transfer Theory

Reynolds, 1996

ReviewReview

• 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?

Electrofishing EquipmentElectrofishing Equipment

There are a variety of electrofishers systems out there…

Backpack electrofishin

Tote-barge electrofishing

Boat electrofishingBoat electrofishing

Main Components of the Electrofishing System

1. Control Unit2. Power Source3. Electrodes

Power SourcesPower Sources

Battery Generator

Function of Control UnitsFunction 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

are needed to see this picture.QuickTime™ and a

TIFF (LZW) decompressorare needed to see this picture.

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.

VVP - 15B ElectrofisherVVP - 15B Electrofisher

Produces DC, pulsed DC and AC.

Pulsed DC- Freq 5 - 120Hz, Duty cycle 10-80%.

Burst of Pulses - groups of 3 or 6 at 15 - 120 Hz.

AC - 60 Hz.

LR-24 ElectrofisherLR-24 Electrofisher

Produces DC, pulsed DC, and Burst of Pulses.

Pulsed DC - Freq 1 - 120Hz, Duty cycle 1 - 99%.

Burst of Pulses - 1 - 1000Hz

Electrodes - Backpack and Shore-based

AnodesAnodes

Cathodes Cathodes

Boat ElectrodesBoat Electrodes

AnodeAnode

CathodeCathode

Important Electrode Parameters

• Size• Shape• Condition• Orientation

Anode SizeAnode Size

Reynolds, 1996

Cathode SizeCathode 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.

• The cathode should have ~3 times the surface area as the anode.

• The larger surface area decreases the electric field intensity near the cathode.

Electrode ShapeElectrode Shape

The electric field is affected by the shape of the electrode.

Electrode ConditionElectrode 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.

Electrode OrientationElectrode 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.

Four Behavioral ZonesFour Behavioral Zones

1. Fright Zone2. Taxis Zone3. Tetanus Zone4. Kill Zone

Fish Behavior DefinitionsFish Behavior Definitions

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

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.

QuickTime™ and aH.263 decompressor

Fish InjuryFish 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?

Potential Fish InjuriesPotential Fish Injuries

Stress Syndrome Hemorrhaging Vertebral Injury Death Egg Viability and Reproductivity

Stress SyndromeStress 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.

Level Two

Level Three

Fish HemorrhagingFish Hemorrhaging

External “Branding”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.

Vertebral InjuryVertebral Injury

Injuries to FishInjuries to Fish

Fisheries Techniques, Chp 8 Slideshow

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.

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

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)

Conductivity of WaterConductivity of Water

• Easy to produce

injury

• Easy to produce

injury

level of injury

Pulsed DC

Types of Electrical Waveforms

Pros and ConsPros and Cons

Burst of Pulses

• Hard to produce• Low power

requirement• Indications are

low level of injury

“What Settings Should I Use?”

Use the lowest voltage, frequency, and duty cycle combination

that elicits “taxis” but minimizes “tetanus”.

Use the lowest voltage, frequency, and duty cycle combination

that elicits “taxis” but minimizes “tetanus”.

Step 1: Volts

Need enough voltsto get fish to twitch.

If fish twitches and escapes,voltage is high enough!

USFS,Boise ID

A note about voltage….

If you double voltage, power density quadruples.

Power density = (Volts/cm)2 x conductivity

Unpublished Data: Do Not Cite

Hemorrhage DataHemorrhage Data

Vertebral Injury DataVertebral Injury Data

Behavior and Vertebral Damage (Frequency)

Unpublished Data; Do Not Cite

% of Marked Fish Showing Vertebral Damage

Equipment ChoicesEquipment 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

Electrofishing TechniqueElectrofishing 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!”

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!”

What would you change?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?

Care of FishCare 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.

“What should I do if I observe fish with external

marking?”

“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.

ReviewReview

• 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?

“Why Should I Bother With Safety?”

All electrofishers have enough power to kill

humans.

All electrofishers have enough power to kill

humans.

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”.

50-150 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(1- 4.3 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

Life-threatening ConditionLife-threatening Condition

• Cardiac Arrest• Ventricular Fibrillation• Respiratory Arrest

• Lactic Acidosis (delayed onset)

• Cardiac Arrest• Ventricular Fibrillation• Respiratory Arrest

• Lactic Acidosis (delayed onset)

“How Do I Electrofish Safely?”

1. Training2. Proper Equipment3. Crew Preparation4. Emergency Planning5. Operational Safety

TrainingTraining

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.

Proper Equipment - Personal Protection

Equipment

Proper Equipment - Personal Protection

EquipmentRequired1. Non-breathable

Waders or Hip Boots.

2. Non-slip Boots3. Lineman’s GlovesOptional4. PFD or Wading Belt5. Brimmed Hat6. Polarized

Sunglasses

Required1. Non-breathable

Waders or Hip Boots.

2. Non-slip Boots3. Lineman’s GlovesOptional4. PFD or Wading Belt5. Brimmed Hat6. Polarized

Sunglasses

Proper Equipment - Backpack Electrofisher

• Tilt Switch• Anode Pole (Power Output) Switch• Audible Signal• Quick Release Harness• Emergency Kill Switch

Additional Backpack Electrofisher Safety

Features

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)

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.

Crew PreparationCrew 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.

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.

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.

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.

Emergency PlanningEmergency 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.

Operational SafetyOperational 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.

Operational Safety, cont.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.

Crew SafetyCrew Safety

• Accidents happen• Be prepared for

the worst• Safety equipment• Safety procedures

• Accidents happen• Be prepared for

the worst• Safety equipment• Safety procedures

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.

ReviewReview

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?

Applied ElectrofishingApplied 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”

Factors that affect Sampling EfficiencyFactors 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

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

Lake and Pond SamplingLake 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.

Data analysisData 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

ReviewReview

• Electrical Theory• Electrofishing Equipment• Operation and Safety• Applied Electrofishing Methods

SourcesSources

• Department of Health and Human Services. Electrical Safety: Safety and Health for Electrical Trades. 2002.

• Reynolds, James. Electrofishing. Pages 221- 253. B. R. Murphy and D. W. Willis, editors. Fisheries techniques, 2nd edition. American Fisheries Society, Bethesda, MD. 1996.

• Department of Health and Human Services. Electrical Safety: Safety and Health for Electrical Trades. 2002.

• Reynolds, James. Electrofishing. Pages 221- 253. B. R. Murphy and D. W. Willis, editors. Fisheries techniques, 2nd edition. American Fisheries Society, Bethesda, MD. 1996.

Stream SamplingStream 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.

introduction to electrofishing lisa harlan smith-root, inc. lisa harlan smith-root, inc

current voltage slide

current voltage voltage

current conductivity

conductivity slide

voltage conductivity

current free electrons

flow of electrons

current amps

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