Introduction to Electrofishing

INTRODUCTION TO ELECTROFISHINGBASIC ELECTRTCITYSeries and Parallel CircuitsVery few actual circuits are as simple as theillustrations in the preceding section. Commonly,resistances are found connected in avariety of ways. The two fundamental waysof connecting circuits are series and parallelor the two can be combined into series-parallelcombinations.Total VoltageTotal CurrentTotal ResistanceERl + ER2 + ER3 ...etcIRI = IRz = IR3Rl+R2+R3r+#E B"tt.24.0 VoltsElectron flow--->SERIES CIRCUITR3=6 OhmsR1 =12 OhmsPARALLEL CIRCUITR2=6 OhmsThe total resistance of a Series Circuit isthe sum of the individual resistances. In theSeries Circuit, shown above, the electronflow (current) is from the negative terminalof the battery (voltage source) through thefirst resistance, (Rl), then through the second,R2, and then R3 and then back to the positiveterminal of the battery. Because theseresistors are connected in series the currenteverywhere around the closed circuit has thesame value. Although the current is the samethrough all resistors in the example, the totalvoltage divides between them. The voltageappearing across each resistor (voltage drops)can be found with Ohm's Law formulas:Find the voltage and current for each resistorabove. E Rl = (I Rl * Rl) and E R2 = (I RZ xR2) and ER3=0R3xR3)Total Voltase = ERl =ER2 = ER3r+t?l-E B"tt.12.0 VoltsElectron flow--++__E B"tt.120 VoltsR4= 30 OhmsElectron flow* Rl= tQ OhmsTotal ResistanceRror"r = nt+ R2 ffi +ncR1= R2=24 Ohms 24 Ohms+ ISERIES.PARALLEL CIRCUITR2= +60 Ohms ITotal CurrentI Tot"r=E totalR totalR3=12 OhmsR3=120 OhmsTotal Current = IRl + IR2 + IR3Total Resistance = 1/ (1/R1 + 1lR2 + 1/R3 )orFor Two Resistors = RlxR2/ (Rl + R2)In a Parallel Circuit the total resistance isless than the lowest value resistor presentin the circuit. This is because the total currentis always greater than the current in anyindividual resistor. Two formulas for findingthe total resistance are shown above. Thefirst one works for any number of resistors,4while the second will work for two resistors. The batteryvoltage is applied to all three resistors, so they all have thesame applied voltage. Find the Total Resistance, the currentthrough each resistor and the Total Battery Current.Series-Parallel CircuitsMost actual circuits have resistances both in parallel andseries and are called Series-Parallel Circuits. The drawingat left shows a Series-Parallel circuit. The circuit issolved the same as the previous circuits by combing whatwe have learned thus far. The best method of solving thiscircuit is to consider R2 and R3 in parallel as though theyformed a single resistor. Find their equivalent resistance.www. smith -root.com

INTRODUCTION TO ELECTROFISHINGBASIC ELECTRICITYpower Efficiency. In devices such as batteries, generators. transformers and transistors used in electrofishing,the object is to deliver power into water, rather than converting the power into heat. Power used in heatingis a loss, because it is not useful power. The efficiency of any device is the actual output power, dividedby the input power to the device. That is:Eff' x (100)=Po/PiWhere: Eff.= Efficiency (expressed as a percent)Po= Power output (watts)Pi= Power input (watts)Intheelectrofishercircuitbe1ow,whatistheinputpower?-__--__--*1dG1qolelflo1q q.1rl.1q q-1What is the output power ?WhatistheEfficiencyoftheelectrofisher'expressedasa7o?Note; Observe how the meters are connected to make these readings.6Reading =17.5 AmpsE g"tt.Reading =23.0 VoltsElectrofisherwww.smith-root.comReading =805 MilliampsANODEl -IIII\ -CATHODE- l.l.,1c'liF]tsiFiFiFiFv7vFFFFFFFFv.|'IF0{c e47

INTRODUCTION TO ELECTROFISHINCBASTC ELECTRICITYThe Ohm's Law Circle below can be used to solve all relationships between Voltage, Current, power andOhms. To use the Ohm's Law Circle, cover the unknown parameter ei. (P, I, E or R at the center of thecircle) and use any combination of two known parameters, (the outer sections of the circle). to solve theequation.Ohm's Law for Electrofishing The Ohm's Law parameters, above are equivalent when considered in a watermedium. They become:Current Density (amperes) = Voltage Gradient (Volts/cm)Resistivity (Ohms-cm)E=Voltage Gradient (volts/cm) =Current Density (Amps/cm^2) X Resistivity (Ohms-cm)Resistivity (Ohm-cm) = Voltage Gradient (Volts/cm)Current Density (Amps/cm^2)P -Mho =watts / cm3 = current Density (Amps/cm^2) X voltage Gradient (vlcm;Conductivity (Mhos/cm) = l/Resistivity (Ohms-cm)pMho - l/Resistivity (Ohm-cm)x10^-6Note: In a purely resistive circuit, such as electrodes in water, ohm's Law applies to DC,Pulsed DC and AC at any normal electrofishing frequency.Photos of m,agnetic field, pattenls ptoduced bU ilon fi.lirtgs.(a) Field bctueen opposite Ttoles. The N and S poles c

INTRODUCTION TO ELECTROFISHINGwww. smith-root.comI

INTRODUCTION TO ELECTROFISHINGETECTROFISIIIilG SAFETYSAFE FISHINGElectrofishing equipment uses voltages and currents thatcan be lethal to humans. The operators must always keepin mind that the chance of receiving an electrical shock ismultiplied in or near water. Using an electrofisherlikeusing a firearm: if used properly and with good judgmentit is perfectly safe; lose respect for it and you can loseyour life!Electrical equipment used in a moist field environmentis always subjecto deterioration that could lead todangerous electrical shock. Field equipment is alsosubjected to vibration and impact during transporting andwhile in operation. Often equipment shared by differentcrews does not receive proper maintenance or a completeFollow the safety guidelines, and use good commonsense to handle unforeseen circumstances.All personnel involved in electrofishing should be taughtthe fundamentals of electricity, and have an understandingof the safety requirements.The most important factor in electrofishing efficiencyand safety is the training and experience of the crew. Atleast two members of the crew should be qualified toadminister cardiopulmonary resuscitation. As opportunitiesarise, all crew membershould attend a course inbasic I ife-support training.ELECTRICAL SHOCKIt is the currenthat passes through the human body thatdoes the damage. The voltage is relevant, because it isthe force that "pushes" the currenthrough the body.Experiments show that 20 to 500 Hz AC current is moredangerous than DC, or higher frequencies of AC.The voltages used by electrofishing gear cause death byone of three means:Ventricular FibrillationVentricular fibrillation is uncoordinated contraction ofthe muscles of the heart. The heart quivers rather thanbeats. Electrical currenthrough the chest can cause thiscondition. Once a person goes into ventricular fibrillation,the only way to stop the quivering is to use a defibrillatorthat applies a pulse shock to the chesto restore heartrhythm. Cardiopulmonary resuscitation may help to keepa victim alive until he can be defibrillated.Respiratory ArrestThe respiratory center is at the base of the skull. Thus,shocks to the head can cause the breathing to stop.Artificial respiration by the mouth-to-mouth methodshould be used in this case.AsphyxiaAsphyxia is caused by contraction of the chest muscles.When a current is above a certain level, a person cannotlet go of an electrically hot wire. Currents above thislevel may not cause ventricular fibrillation, but maybe enough to cause contraction of the chest muscles. Ifthe current is not stopped, or the victim is not removedfrom the point of electrical contact, asphyxia will result.Artificial respiration or cardiopulmonary resuscitationmav be necessary.www. smith - root.com 11

INTRODUCTION TO ELECTROFISHINCELECTROFISIIIilG SAFELYPREVENTING ELECTRICALSHOCKElectricity needs to have a complet electricalcircuit in order for current to flow. The only I . Never electrofi sh alone ! A minimum of two properly trainedway that you can get shocked is if you become people are required for every electrofishing crew.the electrical conductor to complete the circuit. 2. A crew leader shall be appointed for all electrofishing. TheThe current flows from the cathode to the anode crew leader is responsible for the safety ofthe crew, and thethrough the water. The water is the electrical enforcement of all safety regulations.conductor. If you touched both the anode and 3. The crew leader, and at least one additional crew member,the cathode you would become an electrical shall receive training in cardiopulmonary resuscitationconductor and complete the circuit path and get a (CPR), and First Aid.sever electrical shock. If you were to touch only4. All electrofishing personnel shall receive training inone of the electrodes, you would not completefundamentals of electricity and safety.the electrical circuit and not get shocked.5. Check your electrofisher before each operation. to ensureWARNING z Touching any electrode is notthat it is in good working order.recommended. Unless all conductive obiectsyou come into contact with are connected to the 6. Turn off your electrofisher before making any connectionssame electrode, you will be shocked to find a or part replacements.current path that is not obvious, e,9., the water, 7. When not in use, and when transporting the unit, disconnector the boat.the power supply.Preventing electrical shock means preventing 8. Check that the electrofisher gives an audible signal whenelectrical current from entering and flowing there is voltage present at the anode.through parts of the body. The skin is a partial 9. Do not make any field modiflcations to your electrofisherbut variable barrier, because it offers resistance without written approval from the manufacturer or ato the passage of electrical current. Tough skin qualifi ed electrical engineer.has more resistance than tender skin, and dry skin 10. Use only dip nets with insulated handles.more then wet skin. But tough dry skin alone doesI l. Wear personnel flotation devices.not offer enough protection for electrofishing.12. Wear lineman's gloves, rated 5,000V minimum.Rubber lineman's gloves, rated 5,000V minimum13. Never reach into the water in vicinity of an electrode, evenshould always be worn.if rubber gloves are being worn.Even while wearing rubber gloves and waders,14. Take frequent breaks. Stress and fatigue endanger the crew.never touch an electrode while the circuit is15. Practice the quick release system as shown on page C-6.energized.Do not work on the electrical system while thegenerator is running. Do not enter the waterwhile the current is on during boom shockingoperations.A severe electrical shock from electrofishingearmay result in the need for artificial respiration;therefore it is imperative that no one ever worksalone.To prevent electrical shock all electricalequipment should be carefully inspectedbefore each field operation. With all electricalequipment in good operating condition, andall insulation, junction boxes, bonding, andconnections intact, there is much less danger ofreceiving an electrical shock.1IxIIo1f1qolo1olq qqolq]1ttlqq1111qrlqr'1IqqqqGlG1t1cl112 www. smith- root.com

INTRODUCTION TO ELECTROFISHINGELECTROFISHIIIIG SAFELYBACKPACK SAFETYl. Before each operation, check that the frame emergencyrelease is in working order and check that the tiltDo's:switch shuts off power if the unit is tipped more than l. Always be sure that all personnel are clear of the45"electrodes before turning on the power.2. Wear hip boots or chest-high waders, with non-skid 2. Know how to administer first aid treatment forsoles.electrical shock.3. Wear polarized sunglasses to help you detect subsurfacehazards and obstacles. Beware of turbid water 4. Have electrical circuits checked only by qualified3. Wear flotation devices.that can hide unseen sub-surface obstacles and sudden technicians.drop-offs.5. Disconnect the power supply when the electrofisher4. Shut off your electrofisher before entering or leaving a not in use.stream.Don'ts:5. Do not operate an anode pole when carrying abackpack unit weighing more than 20 pounds when in l. Don't electrofish alonelhazardous conditions.2. Don't continue to electrofish if your boots or gloves6. If you get water in boots, waders, or gloves, stop work get wet inside.immediately and get dry clothing3. Don't operate an electrofisher if you have had any7. Operate slowly and carefully. Footing in most streams prior heart ailments.is poor, and most falls often occur when operators are 4. Don't operate generators without covers or screens.hunying.5. Don't operate generators without a spark arrester.Ground the generator to the boat hull.Be sure that all the metal parts on the boat are bondedto each other electrically.3. Run all cables through electrical conduit, or use aheavy-duty rubber-covered cord recommended forwet locations.4. Make all electrical connections in water-tight junctionboxes.5. Each dip netter should have his own foot switchto control the output. The switch should be wiredin series with the emergency off switch of the boatoperator.6. When wading with a boat, even in shallow water,chest waders should be worn. An operator may trip,end up in a kneeling or sitting position in the waterand receive a shock.-All crew members must be alert Operators whocontrol the power switch must be constantly aware ofthe netters in the electrical field.www.smith- root.comr3

INTRODUCTION TO ELECTROFISHINGETECTROFISHI]TG SAFELYIt may be necessary in some circumstances to remove the electrofisher backpack quickly.The LR-24 has an integral quick release pack frame. Just press the latch tabs on the waist belt and shoulderstraps and the entire LF.-24 falls away.CAUTION: Always unlatch the chest strap of the pack before entering or crossing water. If left latchedthis strap may prevent the user from quickly removing the LR-24 in the event of an emergency, such asfalling into deep water.This should only be done in an emergenc]-situation! The backpack may be damaged fromcontact with the ground andlor water when usingthe quick release system.4 7lx4qqqqqq71The following procedure illustrates how thequick release system is designed to work.1. Squeeze the release tabs on hip belt buckle toremove hip belt.2. Squeeze the release tabs on on either cheststrap.3. With strap detached, shrug off opposite strap.This will allow the pack to fall away from youvery quickly!4. Move away from pack as it falls..14 www.smith- root.comqqudjaF;FFFF7FFFFFFIF;FFltFt',!d

FFFFFFEFllll-?l-l-t-f-f-t-l-f.f-f-l-i-r------aaSAFETY NOTESINTRODUCTION TO ELECTROFISHINGETECTROFISHIIUG SAFETY,www. smith-root.comp15

INTRODUCTION TO ELECTROFISHINGELECTROFISHTIUG PRIIUCIPLESE LECTROFISHIIUG PRIIIICIPLESINTRODUCTION TOELECTROFISHINGINTRODUCTION TO ELECTROFISHINCWATER CONDUCTIVITYFor many years it has been known that fish reacto electric The conductivity of the water and that of the fish's fleshcurrent passed through water. Electricity was first used are the factors that affect electrofishing most.for fishing in 1863 when a British patent was granted. The conductivity of water depends on the quantity ofMajor efforts to apply electricity as a tool in fisheries dissolved salts and mineralsthe water. The conductivitymanagement did not occur until after 1950. Since then of potable waters in the United States ranges from 20 todetailed studies have been made on the physiological2,000 microSiemens/cc. Sufficient current at realisticeffects of electricity on aquatic organisms.power levels will flow through water in this range toelectrofi sh successfully.RESPONSE OF FISH TOFigure 2 illustrates the field patterns caused by theELECTRICITYpresence of a fish in water. In (a) no distortion is causedTo collect fish by electrical means we must create an by the presence of the fish. In low conductivity water,electrified zone of sufficient amplitude to stun fish. In the (b), the distortion of the electric field is such that thebasic electrofishing circuit, shown in Figure 1, a current voltage near the fish is less than it was before the fishis passed between submerged electrodes. A fish between was present. The reverse is true in (c) where the waterthese electrodes forms part of a closed circuit and some conductivity is more than that of the fish. In this casecurrent flows through its body.the distortion is caused by the current concentratingThe effectiveness of the electrofisher is affected by nine the water sunounding the fish. In both (b) and (c) not asfactors: voltage, electrode shape, water conductivity, much power is transfened into the fish's body as in (a).water temperature, conductivity of the stream bed, fish'sdistance, size, species, and time in the field.Figure 1.If these environmental factors are too far out of line, poorThe basic electrofishing circuit.electrofishing will result. To some extent, the effects ofchanges in water conductivity may be compensated forby changing the output voltage.a. Eoual conductivities b. Fish more conductivec. Water more conductiveFigure 2.Electric field patternscaused by fish.Axtq]'lqqat'{q qqqqiiiqqrliqf1qqt f,1r6www.smith- root.com

INTRODUCTION TO ELECTROFISHINGELECTROFISHIIUG PRIITICTPTESLOW CONDUCTIVITY WATERDistilled water is a very good insulator. It has aconductivity range of 0.5 to 5.0 microSiemens/A fish will receive the maximum shock through its body whencc. If a normal voltage is applied in distilledthe conductivity of the water is the same as the conductivity ofwater, very little cunent will flow. Power flow isthe fish's flesh. Unfortunately, this is rarely the case.too low to be effective for electrofishing.Fish flesh conductivity ranges from 500 to 1,500 microSiemens/The current passing through a fish decreasescc. Each species has a different conductivity. This affects theiras the power flow decreases. To get the samesusceptibility to electric cunent.response from fish, the cunent can be maintainedConductivities for some fish species are:by either increasing the voltage, or by keepingTrout I,220 microSiemens/ccthe resistance low.Perch I,089 microSiemens/ccIf a higher voltage is used, up to 1,200 volts mayCarp 870 microSiemens/ccbe necessary. High voltages create three problems,Grudgeon 814 microSiemens/ccspecial electrical equipment is required, safetyE. Halsband - Vilbert 1967is reduced for the operators, and conditions are FISH SIZElethal for fish close to electrodes.Among fishTheof the sameresistancespecies,canthe largerbe keptfishlow by increasingare more sensitivetheto electrical currents. Fishsizeabsorb powerof the electrodes. Theasonly limitationsa functionto thisof bodysurface area. This isare the availabilityimportanto rememberof largerif youelectrodes,areand theshockingfor small fish and largeweightfish areof electrodealso present.thatThecan be handledlargebyfishthearegoing to receive a much greateroperator.shock than the small fish.HIGH CONDUCTIVITY WATERFISH CONDUCTIVITYTEMPERATUREWater conductivityHighandconductivityeffective fishisconductivityover 2,000 microSiemens/increase withhigher temperature.cc. If a high voltage is applied, most cunent willConductivities reportedflowforeasily throughCarp:the water and the fish will50 372hardlymicroSiemens/ccbe affected. The electric current follows10" 543the pathmicroSiemens/ccof least resistance and bypasses the15'7r4 microSiemens/ccfish completely. Therefore use low voltages and20'1,026highmicroSiemens/cccurrents. Currents as high as 60 amps are25" 1,969 microSiemens/cccommon, the limiting factor being the rating ofWhitney andthe power-supply.Pierce 1957Some brackish water and industrial waste water SUBSTRATEhave conductivities over 10,000 microSiemens/Certain bottom substrates will conduct electrical cunent. Thesecc. Here smaller power-supplies are unable to weaken the electric field in the water, making fish capture lessdeliver enough power to stun fish. Waters in thiseffective.range can only be electrofished effectively withthe larger model GPPs.ADJUSTING THE VOLTAGEThe Smith-Root 7.5 GPP outputs 62 amps By adjusting the output voltage, the effects of the water'sthrough 8 gauge stranded cables. This unit can conductivity on electrofishing can be reduced.stun large fish in the interface between fresh and The current flowing through the water is directly related to thesalt water. For example, Striped Bass can be voltage applied. The higher the voltage, the greater the cunentstunned for taking brood stock.will be.Theoretically high conductivity could be dealt When adjusting the output voltage the major consideration is thewith by using smaller electrodes, but this would power being used. This is especially true for battery poweredreduce the range and also create damaging current electrofishers. Power is equal to the voltage multiplied by thedensities near the awww. smith -root.com ,17

INTRODUCTION TO ELECTROFISHINGELECTROFISHIIUG PRIIUCIPLEScurrent. When figuring the power for an electrofisher, The switch gives several on-off pulses per second. Thethe fact that it is usually putting out pulsed DC must number of pulses per second (pulse frequency) and thebe taken into consideration. The instantaneous power on time (pulse width) have different effects on differentduring a pulse may be quite high, but if the electrofisherspeciesfish.is only producing pulses ata257o duty cycle, the averageIn a pulsed DC field a fish's body flexes with each pulse,power would be approxim ately 257o of the instantaneous and returns to normal between pulses. This flexing andpower.straightening accentuates the involuntary swimmingtowards the anode. called galvanotaxis.ALTERNATING CURRENT6 " 0z2'FAlternating Current (AC) is an electrical current in whichthe direction of current flow reverses a number of timesGalvanotaxis: In pulsed DC a fish's bodyper second.flexes with each pulse.In an AC field, the fish takes a position transverse tothe electrical field lines and attempts to face the anode Smith-Root Programmable Output Waveforms give youand cathode successively, in rhythm with the AC cycle. complete control over your electrofisher output. ThisWhen the field strength increases, tetany occurs, and the patented method of synthesizing waveforms makes itfish is stunned. Strong contractions of the body musclespossibleto produce virtually any waveform, so you canmake the fish feel rigid.select the one that is safest for the fish. POW allows youAt high voltages, the larger fish may be killed, the to create nanow pulses to achieve the same results asmuscular contractions being so severe that vertebrae are wide pulses. Narrower pulses put less power into thefractured and the brain damaged. HenceAC electroflshingwater.This has three benefits: you have less chance ofis only successful with small fish in low conductivitydamageto the fish, your battery or fuel lasts longer, andwater.you can work in very conductive water that overloadsconventional electrofi shers.DIRECT CURRENTstraight strarght straight ''"'RESPONSE OF FISH TO DC FIELDSDirect Cunent (DC) is the term given to electrical currentthat flows only in one direction. The current flows from An electric field in water can be considered to have threethe negativelectrode (cathode) to the positive electrodeseparateareas. The outer peripheral area is a weak field(anode).that the fish is indifferento. The next area, closer to theThe reaction offish to direct current is quite different from electrodes, has a stronger electrical field, but not enoughtheir reaction to alternating cunent. The first reaction of to stun the fish. In this area, the involuntary swimmingthe fish is to turn toward the anode and start to swim action will occur and the fish will swim towards thetoward it until it reaches an electrical field strong enough anode. The innermost area has the strongest electricalto stun it. Being stunned is called galvanonarcosis. The field, and the fish within it are immobilized.severe muscle contractions caused by AC do not occur,and the fish recover much faster. Mortality rate is much Zone of Indifferencelower with direct cunent.When electrofishing first starts fish are usually hiding upto three meters away, so high power is required to attractPULSED DIRECT CURRENTthem out of hiding. But as the fish nears the anode, highEven greater anode attraction is possible with pulse direct power can injure it.current. Pulsed direct current is made by intenuptingsteady DC with an electronically controlled switch.18 www.smith- root.com1Iflqtqrlq rlc1q qqqqolqt''1qo1rlrlqGlGlclFtFtFtGl14de4G1clC1r,1

INTRODUCTION TO ELECTROFISHINGETECTROFISHTIUG PRITTICTPTESVoltage across fish .- 6.25 +

INTRODUCTION TO ELECTROFISHINGETECTROFISHIIUG PR|n|CIPLESelectrodes. Note that the 20cm electrode reaches outfafther, producing 7 volts head-to-tailbetween 1.0 and 1.2l. Larger electrodes have lower resistance, need moremeter from the electrode; as opposed to only 4 volts forcurrent at given voltage, reach out farther, and havethe smaller electrode at the same distance. Note also thatlower maximum voltage gradient.the voltage the fish receives closer to the electrode is less2. Small electrodes pose a hazard to fish because offor the larger electrode (100 volts instead of 144 volts).high cunent density and voltage gradient.Larger electrode thus offers two advantages: greaterange,3. Electrodes placed farther apart use less current, butand lower maximum gradient.the savings are not large.One drawback is that a larger electrode also has greater4. The resistance of an electrode varies in directcircuit loading, and thus draws more cunent for the same proportion to water resistivity.voltage (twice as much for the double size electrode).Thus, a larger electrode requires a larger generator. This RING ELECTRODESdictates a practical upper limit on electrode size for a 1. Once spacing exceeds 10 radii, the distance betweengiven generator and water conductivity. Except for this electrodes is insignifi cant.limitation, the larger the electrode, the better the fishingeffectiveness and the easier it is on the fish.Figure 7 shows that larger electrodes increase the fish'lOcmcollection area. The shaded areas have a voltage gradientbetween 0.12 and 1.2 volts per cm, and are suitable forelectrofishing. The applied voltage is 300 volts.o(sIooouJFigure 4. The field pattern, and the variation of gradientbetween two electrodes.20 www.smith- root.comELECTRODE BEHAVIOR0.0 0.2 0.4 0.6 0.8 1.0 1.2Distance from electrode centers (meters)Figure 5. Gomparison of two sizes of anode.11 2r100 66144 >' I'-il,l;I100 )'.,+II1oo:1r44 'ft 16 +-1+ 10i volts i66 502rlttvolts8rtzkrt -II- t -III400.0 0.2 0.4 0.6 0.8 1.0 1.2Distance from electrode centers (meters)Figure 6. Comparison of effects of two sizes of anode.I3rlllI4(I{ rI4r-l11Fl4F1qadV'IV';FIv.FFFFFFFFFFFFFFvGGGUtFtFGGGGGGJrGG

INTRODUCTION TO ELECTROFISHINGETECTROFTSHIiIG PRIIUCIPTES6.il6rh2) 10,18rn')2.tt7ril 2Il6.S3nt'0.00.20.4 0.60.8 1.01.2 1.4 1.61.82.O 2.2Distance from electrode centers (meters)Figure 7. Larger anodes increase the fishing area.2. The region affected by the electrode islimited to 5 to 10 radii.3 Electrode resistanceprimarily dependenton electrode radius, and varies in inverseproportion to radius.4. Forring electrodes, the cros section diameterof the ring material is of little importance.If the ratio of cross section diameter to ringradius is held constant. resistance variesinversely with ring radius.CATHODESIn electrofishing it is desirable to have a highvoltage gradient around the anode, and a lowvoltage gradient around the cathode.Figure 8 shows variation of voltage, as a functionof the distance from the fishing anode, for threetypes of cathode. It shows that it is advantageousto have the potential of the water as near aspossible to that of the cathode.The required voltage is reduced by diminishingthe resistance of the cathode field. Thiscompensates for the reduced resistance so that thecurrent does not vary. The power consumption isdirectly proportional to the voltage used.One advantage of a large cathode is that the riskof accidental electrocution is much reduced. Alarge cathode has very low potential with respectto the soil and the water around it. The resistancebetween the cathode and the water is halvedeach time the surface of the cathode is doubled. For example,a 100 square foot cathode would need another 100 square footadded to pass from g to 4.5 ohm. However a cathode larger than100 square feet would be inconvenient to handle for shore-sideelectrofishing.Figure 9 comparesmall and a large cathodes. With a standardgrid cathode, the anode voltage falls distinctly from 324 to 265volts when using two anodes. However with a very large rvirenetting cathod efficiency falls only slightly from324 ro 302volts when using two anodes.For shore-side operations, the cathode surface presents the leastresistance when it is divided into several parts placed severalmeters apart. An electrode is more effective when its form isleast concentrated. For example , a 3'Yl2' strip is more effectivethan a square of 6'Y6'.Figure 10 illustrates the variation in both voltage and gradientbetween the electrodes.Whenever possible, the cathode should be placed in parts of thestream that you do not wish to fish, or even in parts completelyseparated from the stream itself. The anode should never beallowed to come close to where the cathode is located.o(!= o(d500450400350200150o)N=(It\... Cathode Indentical to anode: 6OOV, 6.3kW=\\\\\\\\\\NN\\.o'\ro \ .EU)1000.5m2 grid cathode: 350V, S.7kW\llr..ooN5010m2 wire netting cathode: 310V,3.2kW\slss*s*.-...*.rr,.,.\00c) 2 4 6 4 4 4 6 4R O'ttoc(g Distance from center of anode (meters)Figure 8. Variation of voltage for three kinds of anode.www. smith-root.com21E oo o

INTRODUCTION TO ELECTROFISHINCETECTROFISHT]UG PRIIUCTPTESBoat CathodesMany aluminum electrofishing boats use the boathull as the cathode and the boom electrodes as theQ ( ^c^n (Janode. This is perfectly safe as long as you never a 300I=come in contact with the anode and complete the2q oelectrical circuit. The National Safety Council in-lE 200^^ iz-v ctheir data sheet #1-696-85 does not recommend -0)0)1 F ;Iusing the boat hull as the cathode, but we have o 100-.11.0 o,yet to hear of any accidents occurring because6v'wcof it.c)Figure 1l shows a Smith-Rootote barge(Lo 2 4 4 6 4 8 6 )designed for stream wading operations. NoteItttp Distance from center of anode (meters)the large cathode plate attached to the bottomEof the fiberglass hull. The anode is a pair of ringand gradientelectrodes about 28cm (1I") in diametermountedon fiberglass poles. With this arrangement, the associated with the larger cathode.resistance of the anode pair is four times the The SR-6 field tested with two 28cm anodes and a voltagecathode resistance. Thus, four times as much of 240 volts, showed good fishing effectiveness in 400voltage appears in the anode field as in the microSiemens/cc conductivity with a current of 3 to 4 amperes.cathode field, and consequently 80Vo of the In lower conductivities of 40 microSiemens/cc, a cunent of Iapplied voltage appears at each electrode. to 1.5 amp is effective. This data may serve as a useful benchmarkto judge whether a unit is operating under conditionsuchThe situation could be further improved byenlarging the cathode, but a point of diminishing that fish should be caught. If the electrical performance is closereturns is reached. Doubling the cathode size to this reference point, and fish are not being caught, it is safe towould halve the cathode resistance and give an 8 conclude there are few fish in the area.to I ratio between anode and cathode resistance.Now 887o of the voltage would appear at theanode. This is only an 87o improvement, andis not worth the additional physical problemsResistance ohmsof cathodeof anode fieldbetween anode and cathodePotential ditlerence voltsbetween cathode and waterbetween anode and watertotalCurrenl ampsPower kilowattsResislivity of the water in all cases=143Fmho/cmStandard 0.5#grid cathodes a.one$ anode35901251263244503.61.62b. twoanodes5085185265450592.38c. oneanodeI90993232432636128Figure 9. Gomparison of two sizes of cathode.d. twoanodesI50593023s6602.1522 www. smith-root.com'\Large wirenettingcathode\;-\ 'l\ Cathode plate\-l . iPulsatorFigure 11. Boftom mounted cathode plate on SR-6.t')eqfflqq(FGG(FGlaGG(FGGJ'J'GGGGGGGJ'J'GGGlFGu,]FGlt]FlFJlrF|Frlc'111

INTRODUCTION TO ELECTROFISHINGETECTROFISHI]IIG PRIIUCIPLESAn operator engaged in electrofishing must wade or float,depending upon the depth and swiftness of the water.WADINGIn shallow slow-moving waters the operators can wadeand probe the anode into likely fish habitat. Wadingupstream eliminates the effects of turbidity caused bybottom sediment. Furthermore, if collections are for foodhabitat study, stunned prey are not swept downstreamand consumed by predators. Fish that manage to escapeare often captured a short distance downstream. Closinga stream with seine nets at each end of the study areahelps prevent the loss of stunned and frightened fish.BOATSNIGHT FISHINGElectrofishing at night with lights is five to ten timesmore effective than daytime fishing, especially in lakes.In streams the reflection of the spotlight on the ruffledsurface makes the fish difficult to see. Boats have floodlights on the bow to attract the fish and to help locatestunned fish.SURPRISECollecting can be enhanced by introducing the elementof surprise through intermittent fishing. The intensity ofthe anode's peripheral field often frightens fish, causingthem to bolt and hide. Do not work with the power oncontinuously, but turn it on only in likely habitats. Fishcan be enticed from under areas of heavy cover or iceby inserting a portable anode, turning the power on, andwithdrawing the anode slowly and smoothly. Fish willfollow the anode, under the influence of galvanotaxis,into the open where they can be netted.CLARITY AND DEPTHClarity of the water limits the ease of capturing fish. TheBoat electrofishers are used in lakes and in streamslengththatof the dip net handles and the visibility of the fishare too deep or swift to wade. Boats have the advantagelimit the depth of effective electrofishing. In general,ofbeing able to carry large generators and holdingwaterstanksover ten feet deep cannot be sampled effectively.for the stunned fish. Electrofishing boats typicallyForhavedaytime fishing polarized sunglasses help in locatingtwo insulated booms extending from the bow. Fromstunned fish.the end of the booms electrodes hang into the water. VEGETATIONUsually one boom is used as the anode and the otheras theAquaticcathode.vegetationThegrowsboat operator guidesbetter fromthe boatcertainwhilesubstratesthe electrofishingand can hindercrew activateselectrofishingthe electrofisherby foulingwhenelectrodes andapproachingentanglinglikely habitat.stunned fi sh.WATER VELOCITYElectrofishing in flowing water is not as effective as instill water, since fish are swept away from the electricfield and netting is more difficult. Also, it is moredifficult to see a fish in fast flowing water, and operatorscan loose their footing. Flows greater than 5 feet persecond usually produce poor electrofishing efficiencies.www. smith -root.com23

INTRODUCTION TO ELECTROFISHINGELECTROFISHIIIIG PRIIIICIPIESModel 12-Bl15-D Settings ChartUse this chart to convert settings used with the 12-B or l5-D to settings on the LF.-24.Example: If F4 were used with the model 12-B, the corresponding settings for the LR-24 would be 30Hzat l27o Duty cycle. Note that as you set the duty cycle the LR-24 display shows the pulse width (4ms inthis case).ABcDEFGHIJKLMNoStandard PulsesABcDEF1 2 3 4 5 61Hz I 2ms 3ms 4ms 6ms 7ms 8ms5Hz | 1ms 2ms 3ms 4ms 6ms 8ms10Hz | 500ps 1ms 2ms 4ms 6ms 8ms15Hz | 500ps 1ms 2ms 4ms 6ms 8ms2OHzl500ps 1ms 2ms 4ms 6ms 8ms3OHz I 500ps 1ms 2ms 4ms 6ms 8msaOHzl50Ops 1ms 2ms 4ms 6ms 8ms50Hz I 500ps 1ms 2ms 4ms 6ms 8ms60Hz | 500ps 1ms 2ms 4ms 6ms 8ms7OHzl500ps 1ms 2ms 4ms 6ms 8msSOHz I 500ps 1ms 2ms 4ms 6ms 8ms90Hz | 500ps lms 2ms 4ms 6ms 8ms100H2 | 100ps 500ps 1ms zms 4ms 6ms110H2 | 100ps 500ps 1ms 2ms 4ms 6ms12OHz I tOOps 500ps 1ms 2ms 3ms 4msHigh to Low Varying FrequencyGHIJKLMNoh--:-,--r 12 13 14 15 168G€ Hz6G€ Hz4O4Hz80-€ Hz6G€ HZ4o4Hz8G€ Hz6G€ Hz4O4Hz2sec 4sec 6sec Ssec 10sec1ms 'lms 1ms 1ms 1ms1ms 1ms 1ms 1ms 1ms1ms 1ms 1ms 1ms 1ms2ms 2ms 2ms 2ms 2ms2ms 2ms 2ms 2ms 2ms2ms 2ms 2ms 2ms 2ms4ms 4ms 4ms 4ms 4ms4ms 4ms 4ms 4ms 4ms4ms 4ms 4ms 4ms 4ms6ms 6ms 6ms 6ms 6ms6ms 6ms 6ms 6ms 6ms6ms 6ms 6ms 6ms 6ms8ms 8ms 8ms 8ms 8ms8ms 8ms 8ms 8ms 8ms8ms 8ms 8ms 8ms 8msABcDEFGHIJKLMNoWide to Narrow Varying WidthD^^i-/E^i7 8 I 10 112sec 4sec 6sec Ssec 10sec15Hz 15Hz 15Hz 15Hz 15Hz15Hz 15Hz 15Hz 15Hz 15Hz15Hz 15Hz 15Hz 15Hz 15Hz84.4ms 30Hz 30Hz 30Hz 30Hz 30Hz6-O.3ms 30Hz 30Hz 30Hz 30Hz 30Hz4{).2ms 30Hz 30Hz 30Hz 30Hz 30Hz8{.4ms 45Hz 45Hz 45Hz 45Hz 45Hz6-O.3ms 45Hz 45Hz 45Hz 45Hz 45Hz4{.2ms 45Hz 45Hz 45Hz 45Hz 45Hz8{.4ms 60Hz 60Hz 60Hz 60Hz 6OHz6{.3ms 60Hz 60Hz 60Hz 60Hz 60Hz4-O.2ms 60Hz 60Hz 60Hz 60Hz 60Hz80Hz 80Hz 80Hz SOHz 80Hz80Hz 80Hz 80Hz 80Hz 80Hz80Hz 80Hz 8OHz 80Hz 80Hz::ln lF h rE h! !sM0DEL 12-B |"*dr xift{ srYr{ffirn",,'f,#J"ll!0"I smrru-noor lNc.POW l-J L.LrELEcTR0FISHERF"I $\ARwERwau$Li'rG s6'1r-a'iFG;FFts(i€dFFFFFFrtet6 A24 www.smith-root.com

INTRODUCTION TO ELECTROFISHINGELECTROFISHIITG PRIiICIPTESwww. smith - root.com25

INTRODUCTION TO ELECTROFISHINGELECTROFISHIi|G PRITUCIPLESREFERENCIThe following are books, research papers. and otherreferences on various aspects ofelectrofishing. The ideas andfindings presented in them form the basis for much of thecurrent practice in electrofi shing.1ANAIqaqa4qqqqt4141. Bryan R. Cowdell and Richard A. Valdez, 1994"EffectsofPulsed DC Electrofishing on Adult Roundtail Chub fromthe Colorado River in Colorado." North American Journalof Fisheries Management. Vol. l47. D. E. Snyder and S. A. Johnson, 1991"lndexedBibliography of Electrofishing Literature," Larval FishLaboratory, Colorado State University, Fort Collins,Colorado."Fishing2. I. G. Cowx and P. Lamarque, 1990, WithElectricity- Applications in Freshwater FishenesManagement," Fishing News Books, Blackwell ScientificPublications Ltd. ISBN 0-85238- 167-03.L. G. Cowx, 1990"Developments in Electrofishing,"Fishing News Books, Blackwell Scientific PublicationsLtd. lsBN 0-85238-l 66-2^+.N.G. Sharber and S.W. Carothers, 1988"InfluenceofElectrofishing Pulse Shape on Spinal Injuries in AdultRainbow Trout." North American Journal of FisheriesManagement. 8: 1l'7 -122Michael A. Bozek and Frank J. Rahel, 1991"Comparison5.of Streamside Visual Counts to Electrofishing Estimatesof Colorado River Cutthroat Trout Fry and Adults," NorthAmerican Joumal of Fisheries Manasement. Vol. 118. M. Burridge and G. Goodchild, 1988"A Bibliography ofElectrofishing," Ministry of Natural Resources, FisheriesBranch, Queen's Park, Toronto, Ontario, Canada.9. Alec G. Maule and Matthew G. Mesa, 1994"Efficacy ofElectrofishing to Assess Plasma Cortisol Concentration inJuvenile Chinook Salmon passing Hydroelectric Dams onthe Columbia River." North American Journal of FisheriesManagement. Vol. 1410. N.G. Sharber, S.W. Carothers, J.P. Sharber, J.C. DeVos,D.A. House, 1994"Reducing Electrofishing-InducedInjury of Rainbow Trout," North American Journal ofFisheries Management. 1411. Jeffery C. Barnet and Gary D. Grossman, 1988"Effectsof Direct Cunent Electrofishing on the Mottled Sculpin,"North American Joumal of Fisheries Manasement. Vol. 8qqc1///qe dddJ46."D. W. Novotny and G. R. Priegel,1971 AGuideline forPortable Direct Current Electrofi shing Systems," TechnicalBulletin No. 51, Department of Natural Resources,Madison. Wisconsin26 www. smith- root.com/edc111d1

INTRODUCTION TO ELECTROFISHINGELECTROFISHIIUG PRIIUCIPLESAdequate : suffi cient, satisfactory, proportionate.GLOSSARY OF ELECTROFISHING TERMSAlternating current: an alternating current or cyclic characteristic by a sequence of positive and negativewaves which are equal, usually sinusoidal, and follow each other alternately at regular time intervals.Anode: the positive electrode.Anode (or cathode) Field: in electric fishing, field around the electrode, beyond which the values ofpotential gradient are unimportant.Anodic (cathodic) Curvature: curving of fish body towards the anode (cathode) under the influence of aunidirectional current, when the fish is perpendicular to the current lines.Backpack Electrofishing: Electrofishing in which an electrofishing unit is carried on a person's back witha backpack.Boat Electrofishing: electrofishing in which an electrofishing unit is mounted in a boat.Body Voltage: measured potential difference, between head and tail of a fish in an electric field.Boom Electrofishing: boat electrofishing using a front mounted electrode boom.Bonding: a perrnanent joining of metallic parts to form an electrically conductive path which assureselectrical continuity, with the capacity to safely conduct current.Branch Circuit: the circuit conductors between the final overcurrent device protecting the circuit and theelectrical load(s).Cathode: the negative electrode.Circuit: complete path of an electric current including the source of electric energy.Circuit Breaker: a device designed to open and close a circuit by a non-automatic means, and to open thecircuit automatically on the predetermined overcurrent without damage to itself when properly appliedwithin its rating.Competent: having necessary or adequate ability to perform a task and correctly respond to hazardoussituations.Condenser Dischargs:s: current composed of a steady sequence of exponential discharges.www. smith-root.com27

INTRODUCTION TO ELECTROFISHINGELECTROFTSHIIUG PRIilCIPLESConductance: the reciprocal of resistance measured in ohms.Conductivity (of water): conductance of 1 cube of water of side 1cm. Practical unit: umhos/cm3(microsiemens/cm3)1fl1 ex14q14Critical Zone of Current Density: in electric fishing, current density area around the electrode, in which afish is shocked.Current: quality of electrical charge per unit of time; usually measured on Coulombs/second or Amperes.Current Lines (syn. flow lines, equffiux): imaginary lines which represent direction of current flowperpendicular to equipotential surfaces.Current Shape ( syn.wave form): geometrical shape of the current during one cycle. Usually refers to therate of growth and decay of an impulse.Cycle: one revolution of a period phenomenon back to its starting point.Deadman Switch: a switch requiring constant pressure to supply electrical current to the circuit.Density (of current): current intensity passing through one unit of cross-sectional area perpendicular tothe current lines of an electric field. Unit: mA per cm2 (mAlcm2).Dionetter: see netter.;1rlrlt4q4 qqqrlDirect Current (syn. continuous, galvanic): unidirectional constant or fairy constant current.Discretion: the ability to make responsible decisions.Duty Cycle: ration of time-on to total time within one cycle.Electrical Charge: fundamental positive or negative charged particles measured on Coulombs.4n qa;17Electrofishing: the use of electricity for the capture and/or control of fish.Electrotaxis: fish swimming induced by any kind of electric current.Energy: electrical power measured in watts multiplied by unit time (e.g., wattsec).Ensure: to take all reasonable and necessary measures to make certain that activities are properly28 www. smith-root.com1

INTRODUCTION TO ELECTROF]SHINGELECTROFISHIITG PRIITICIPTESconducted and desired results obtained.Equipotential Surface: a surface all the points of which are at the same potential. Equipotential surfacesare perpendicular to the direction of current flow.External Resistance: electrical resistance between electrodes. Unit: ohm.First Aid Certificate: the appropriate certification as required by the Industrial First Aid Regulations, andwith respecto hazards on the job (i.e. electric shock).Fixation: state of immobility of fish resulting from tetanus under the action of electric current. Distinctfrom galvanonarcosis.Forced Swimming: kind of very fast swimming towards the anode, induced by a constant continuousculTent.Frequency: total number of cycles per time unit. Unit: hertz. I Hz = I cycle per sec.Fright Reaction: avoidance of the electrical field by a fish.Galvanonarcosis: state of immobility of fish resulting from muscular slackening, under the action of aconstant and descendine continuous current.Galvanotaxis: swimming artificially induced by a constant continuous current.Gestaltspannung: body voltage of a determined reaction, constant for a species and independent of fishsize.Good: competent, skillful.Ground: a conducting connection, whether intentional or accidental, between and electrical circuit orequipment and the earth, or to some conducting body that serves in place of the earth.Half Wave Rectified Current: current composed of a sequence of half sine waves in the same direction,separated by pauses of equal duration. Obtained by passing an alternating current through a rectifier.Heterogeneous Field: field in which current density and potential gradient are constant, whatever thedistance from electrodes.Impulse: electric phenomenon of short duration compared to the period.www. smith -root.com29

INTRODUCTION TO ELECTROFISHINGELECTROF ISHIIiIG PRIITCIPLESInhibition of Swimming: slowing down of swimming movements, produced by a low and constantcontinuous current, when a fish faces the anode.Instructor: a person who meets the required training standards for backpack andlor boom(boat)electrofishing.Intemrpted Direct Current: unidirectional current intemrpted by periodic pulses.Isolation Transformer: a transformer inserted into a system to separate one section of the system fromundesirable influences with other sections.Isolines: lines of equal potential gradient.Multiphase Current: n being the number of phases: the whole of n alternating currents originating fromthe same source and out of phase with each other.Narcosis: state of immobility resulting from muscular slackening.Netter: the individual who nets the captured fish during electrofishing operations.Oscillotaxis: swimming artificially induced by an alternating current.Period: time interval between two identical stages in an electrical sequence.Potential Gradient: potential difference in an electric field per unit length in the direction perpendicular tothe equipotential surfaces. Unit: volt per centimeter (V/cm).Power: energy per unit time measured in watts.Pseudo-forced Swimming: out of balance swimming produced by a strong and constant continuouscurrent, when a fish faces the anode.Pulse Duration (syn. pulse length): duration of an impulse.Pulsed Current (syn. pulsating direct current): unidirectional current composed of a sequence of cyclicimpulses.Ouarter Sine Wave Cument: a special kind of current electronically obtained from alternating, usuallyfrom V max. to zero.Rectified Alternating Current: current composed of an unintemrpted sequence of half sine waves in the30 www.smith- root.comq qGJaJafaflFF;GfljlF;tfrf,GGGGG7G;GG;;;GGGlFGGGGitFt114rl

INTRODUCTION TO ELECTROFISHINGELECTROFISHI]UG PRIITCTPLESsame direction, and obtained from an alternating current by means of a 4-way bridge rectifier.Resistance: electrical friction measured in ohms.Resistivity (of water): resistance of one cube of water of side 1 cm. Practical unit: ohm-cm, ohm/cm orohm.cm. Resistivity is the inverse of conductivity.Shore-Based Electrofishing: electrofishing in which an electrofishing unit is stationed on the shore.Smooth Rectified Current: direct current derived from alternating current by using rectifiers and asuitable capacitance-inductance filter. When insufficiently filtered, the current shows weak sinusoidalvariations and is called "partly smoothed rectified current", or ripple current, or undulating current.Spatial summation: cumulative effect produced on a neuron by means of several simultaneous stimuli.Square Wave (syn. rectangular pulses): cyclic waveform with steep rise and fall-time with flat top andbottom.Superior: of higher rank, quality or importance; excellent of its kind.Supervisor: a person employed at any level of the organization who instructs, directs and appraises theperformance of an employee.Taxis: swimming artificially induced by a stimulating agent.Temporal Summation: cumulative effect produced on a neuron by a series of stimuli.Tetanus: state of muscular rigidity.minimal value of current parameter inducing a determined reaction.Tilt Switch: a switch which automatically shuts output power off when the electrofisher is tipped beyondits allowable operating angle.Variable Voltage Pulsator Electrofisher: device used to deliver the pulsed electric current to the water.Voltage: energy per charge measured in volts.Watertight: constructed so that moisture (rain, spray, condensation) will not enter the enclosure.www. smith -root.com3t