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Scientists carrying out a population and species survey using electrofishing equipment
Electrofishing is a common scientific survey method used to sample fish populations to determine abundance, density and species composition. When performed correctly, electrofishing results in no permanent harm to the fish, which return to their natural mobility state in as little as two minutes after being caught.[1]
Electrofishing relies on two electrodes which deliver direct current at high-voltage from the anode to the cathode through the water.[2] When a fish encounters a large enough potential gradient on this path, it becomes affected by the electricity. Usually pulsed direct current (DC) is applied, which causes galvanotaxis in the fish. Galvanotaxis is uncontrolled muscular convulsion that results in the fish swimming towards the anode. Teams of at least two people are recommended for an effective electrofishing crew: one to operate the anode, and the other to catch the stunned fish with a dip net.
Types
Electrofishing by boat
There are three types of electrofishers: backpack models, tote barge models, and boat mounted models, sometimes called a stunboat.[2]
Backpack electrofisher generators are either battery or gas powered. They employ a transformer to pulse the current before it is delivered into the water. The anode is located at the end of a long, two meter pole and is usually in the form of a ring. The cathode is a long, three-meter braided steel cable that trails behind the operator. The electrofisher is operated by a deadman's switch on the anode pole. There are a number of safety features built into newer backpack models, such as audible speakers that sound when the unit is operating, tilt-switches that incapacitate the electrofisher if the backpack is tilted more than 45 degrees, and quick-release straps to enable the user to quickly remove the electrofisher in the event of some emergency.
When boat electrofishing, the boat itself is the cathode, and the anode(s) are generally mounted off the bow.[2] The stunned fish swim toward the anode, where they are caught alive using a dip net.[3] Towed barge electrofishers operate similarly to backpack electrofishers, with the exception that the generator is located on a floating barge instead of on a backpack. Often the barge can be left stationary on the shore and longer cathodes and anodes allow the crew to sample large areas. Barge electrofishers often employ gas-powered generators since a user does not have to carry the extra weight on his or her back.
A method of electrofishing using illegally diverted electricity from overhead electric lines is prevalent in parts of the Indian State of Kerala. This can result in accidental deaths due to electrocution.[4]
Effectiveness
The effectiveness of electrofishing is influenced by a variety of biological, technical, logistical, and environmental factors. The catch is often selectively biased as to fish size and species composition. When using pulsed DC for fishing, the pulse rate and the intensity of the electric field strongly influence the size and nature of the catch. The conductivity of the water influences the shape and extent of the electric field and thus affects the field's ability to induce capture-prone behavior in the fish.
It can also cause injury to the fish. The electricity causes muscle spasms that damage the vertebrae. For unknown reasons,[5] this is more common and severe in longer fish.[6]
Due to the conductivity of saltwater, electrofishing is not an effective tool for catching saltwater fish, as the electricity travels through the water, rather than through the fish.[7]
Legality
While electrofishing is used by multiple government agencies, it may be illegal to use it as a form of recreational fishing. This method can be considered poaching. For example, in Florida, as in many other states, it is illegal for recreational use.[7]
Electrofishing is potentially dangerous, or even lethal.[9] The high voltages and currents used, compounded with the presence of water, present serious safety risks. The typical dangers of electrocution, such as electrically-induced unconsciousness and the paralysis of the heart and lungs,[10] are compounded by the risk of drowning, which may result from the aforementioned hazards. In light of this, many safety precautions are taken for those handling electrofishing equipment and those nearby.[2][7][11]
^ ab"FISHNET SHOCKINGS" 2016-12-20 at the Wayback Machine. Toronto Star, December 3, page IN3. Paul Hunter
^ abcd"Tools of the Trade: Electrofishing". news.maryland.gov. Retrieved 2021-06-07.
^. September 2003. Archived from the original on 2007-04-03. Retrieved 2007-08-09.
^Balachandran, Ajay; Krishnan B; Lizha John (2 December 2013). "Accidental Deaths Due to Electrocution During Amateur Electro-Fishing". Journal of Evolution of Medical and Dental Sciences. 2 (48): 9376–9379. doi:10.14260/jemds/1625.
^2003 study: Immobilization Thresholds of Electrofishing Relative to Fish Size, biologists Chad Dolan and Steve Miranda
^Steven R. Dalbey; Thomas E. McMahon; Wade Fredenberg (1 August 1996). "Effect of Electrofishing Pulse Shape and Electrofishing-Induced Spinal Injury on Long-Term Growth and Survival of Wild Rainbow Trout". North American Journal of Fisheries Management. 16 (3): 560–569. doi:10.1577/1548-8675(1996)016<0560:eoepsa>2.3.co;2. S2CID 35356334.
^ abc"Electrofishing FAQ". Florida Fish And Wildlife Conservation Commission. Retrieved 2021-06-07.
^"Dutch pulse-fishing ban upheld by the European Union". 20 April 2021. Retrieved 21 July 2021.
^"Fisheries Safety Handbook | American Fisheries Society". fisheries.org. Retrieved 2021-06-07.
^"Electrical shock: First aid". Mayo Clinic. Retrieved 2021-06-07.
^"241 FW 6, Electrofishing Safety, Fish and Wildlife Service Manual". www.fws.gov. Retrieved 2021-06-07.
External links
Wikimedia Commons has media related to Electrofishing.
electrofishing.net Serving the Global Fisheries Community with Training | Tools | Research 2019-02-12 at the Wayback Machine
Delaware Division of Fish and Wildlife, Fish Monitoring via Electrofishing 2011-02-21 at the Wayback Machine
Electrofishing Effects on Endangered Fishes
International electrofishing email forum 2016-03-04 at the Wayback Machine
Efish Solutions (Equipment to assist with electrofishing, survey work and fisheries management
March 23, 2023
electrofishing, this, article, expanded, with, text, translated, from, corresponding, article, chinese, july, 2022, click, show, important, translation, instructions, machine, translation, like, deepl, google, translate, useful, starting, point, translations, . This article may be expanded with text translated from the corresponding article in Chinese July 2022 Click show for important translation instructions Machine translation like DeepL or Google Translate is a useful starting point for translations but translators must revise errors as necessary and confirm that the translation is accurate rather than simply copy pasting machine translated text into the English Wikipedia Do not translate text that appears unreliable or low quality If possible verify the text with references provided in the foreign language article You must provide copyright attribution in the edit summary accompanying your translation by providing an interlanguage link to the source of your translation A model attribution edit summary is Content in this edit is translated from the existing Chinese Wikipedia article at zh 电力捕鱼 see its history for attribution You should also add the template Translated zh 电力捕鱼 to the talk page For more guidance see Wikipedia Translation Electrofishing is a fishing technique that uses direct current electricity flowing between a submerged cathode and anode This affects the movements of nearby fish so that they swim toward the anode where they can be caught or stunned 1 Scientists carrying out a population and species survey using electrofishing equipment Electrofishing is a common scientific survey method used to sample fish populations to determine abundance density and species composition When performed correctly electrofishing results in no permanent harm to the fish which return to their natural mobility state in as little as two minutes after being caught 1 Contents 1 Method 2 Types 3 Effectiveness 4 Legality 5 Safety 6 See also 7 Notes 8 External linksMethod EditElectrofishing relies on two electrodes which deliver direct current at high voltage from the anode to the cathode through the water 2 When a fish encounters a large enough potential gradient on this path it becomes affected by the electricity Usually pulsed direct current DC is applied which causes galvanotaxis in the fish Galvanotaxis is uncontrolled muscular convulsion that results in the fish swimming towards the anode Teams of at least two people are recommended for an effective electrofishing crew one to operate the anode and the other to catch the stunned fish with a dip net Types Edit Electrofishing by boat There are three types of electrofishers backpack models tote barge models and boat mounted models sometimes called a stunboat 2 Backpack electrofisher generators are either battery or gas powered They employ a transformer to pulse the current before it is delivered into the water The anode is located at the end of a long two meter pole and is usually in the form of a ring The cathode is a long three meter braided steel cable that trails behind the operator The electrofisher is operated by a deadman s switch on the anode pole There are a number of safety features built into newer backpack models such as audible speakers that sound when the unit is operating tilt switches that incapacitate the electrofisher if the backpack is tilted more than 45 degrees and quick release straps to enable the user to quickly remove the electrofisher in the event of some emergency When boat electrofishing the boat itself is the cathode and the anode s are generally mounted off the bow 2 The stunned fish swim toward the anode where they are caught alive using a dip net 3 Towed barge electrofishers operate similarly to backpack electrofishers with the exception that the generator is located on a floating barge instead of on a backpack Often the barge can be left stationary on the shore and longer cathodes and anodes allow the crew to sample large areas Barge electrofishers often employ gas powered generators since a user does not have to carry the extra weight on his or her back A method of electrofishing using illegally diverted electricity from overhead electric lines is prevalent in parts of the Indian State of Kerala This can result in accidental deaths due to electrocution 4 Effectiveness EditThe effectiveness of electrofishing is influenced by a variety of biological technical logistical and environmental factors The catch is often selectively biased as to fish size and species composition When using pulsed DC for fishing the pulse rate and the intensity of the electric field strongly influence the size and nature of the catch The conductivity of the water influences the shape and extent of the electric field and thus affects the field s ability to induce capture prone behavior in the fish It can also cause injury to the fish The electricity causes muscle spasms that damage the vertebrae For unknown reasons 5 this is more common and severe in longer fish 6 Due to the conductivity of saltwater electrofishing is not an effective tool for catching saltwater fish as the electricity travels through the water rather than through the fish 7 Legality EditWhile electrofishing is used by multiple government agencies it may be illegal to use it as a form of recreational fishing This method can be considered poaching For example in Florida as in many other states it is illegal for recreational use 7 The European Union banned pulse trawling in 2006 and again in 2019 the European Court of Justice upheld the ban in 2021 after being challenged by the Dutch government 8 Safety EditElectrofishing is potentially dangerous or even lethal 9 The high voltages and currents used compounded with the presence of water present serious safety risks The typical dangers of electrocution such as electrically induced unconsciousness and the paralysis of the heart and lungs 10 are compounded by the risk of drowning which may result from the aforementioned hazards In light of this many safety precautions are taken for those handling electrofishing equipment and those nearby 2 7 11 See also EditElectric pulse fishingNotes Edit a b FISHNET SHOCKINGS Archived 2016 12 20 at the Wayback Machine Toronto Star December 3 page IN3 Paul Hunter a b c d Tools of the Trade Electrofishing news maryland gov Retrieved 2021 06 07 Electro Fishing Summary September 2003 Archived from the original on 2007 04 03 Retrieved 2007 08 09 Balachandran Ajay Krishnan B Lizha John 2 December 2013 Accidental Deaths Due to Electrocution During Amateur Electro Fishing Journal of Evolution of Medical and Dental Sciences 2 48 9376 9379 doi 10 14260 jemds 1625 2003 study Immobilization Thresholds of Electrofishing Relative to Fish Size biologists Chad Dolan and Steve Miranda Steven R Dalbey Thomas E McMahon Wade Fredenberg 1 August 1996 Effect of Electrofishing Pulse Shape and Electrofishing Induced Spinal Injury on Long Term Growth and Survival of Wild Rainbow Trout North American Journal of Fisheries Management 16 3 560 569 doi 10 1577 1548 8675 1996 016 lt 0560 eoepsa gt 2 3 co 2 S2CID 35356334 a b c Electrofishing FAQ Florida Fish And Wildlife Conservation Commission Retrieved 2021 06 07 Dutch pulse fishing ban upheld by the European Union 20 April 2021 Retrieved 21 July 2021 Fisheries Safety Handbook American Fisheries Society fisheries org Retrieved 2021 06 07 Electrical shock First aid Mayo Clinic Retrieved 2021 06 07 241 FW 6 Electrofishing Safety Fish and Wildlife Service Manual www fws gov Retrieved 2021 06 07 External links Edit Wikimedia Commons has media related to Electrofishing electrofishing net Serving the Global Fisheries Community with Training Tools Research Archived 2019 02 12 at the Wayback Machine Delaware Division of Fish and Wildlife Fish Monitoring via Electrofishing Archived 2011 02 21 at the Wayback Machine Electrofishing Effects on Endangered Fishes International electrofishing email forum Archived 2016 03 04 at the Wayback Machine Electrofishing Archived 2013 09 17 at the Wayback Machine What If xkcd Electrofishing for Whales Efish Solutions Equipment to assist with electrofishing survey work and fisheries management Retrieved from https en wikipedia org w index php title Electrofishing amp oldid 1136634490, wikipedia, wiki, book, books, library,
