Introduction to Electrofishing

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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
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