River Dargle Flood Defence Scheme.
These images were taken during the second full week of July, 2016.
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 fish, which return to their natural state in as little as two minutes after being caught.
Electrofishing relies on two electrodes which deliver direct current at high-voltage from the anode to the cathode through the water. 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 toward the anode. At least two people are required for an effective electrofishing crew: one to operate the anode, and the other to catch the stunned fish with a dip net.
Just like the warnings on hair driers, combining electricity and water can be fatal to both humans and fish. To prevent harm, professionally constructed equipment must be used by properly trained personnel.
Safety gear is an important component of electrofishing. Some important gear for boat electrofishing includes: life jackets, rubber gloves, rubber soled shoes, and nets with fiberglass or wooden handles. For backpack electrofishing, non-breathable waders are also a must.
Life jackets, gloves, heavy duty shoes, and nets with fiberglass handles are a must.
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, 2 meter pole and is usually in the form of a ring. The cathode is a long, 3 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.
Inland Fisheries Ireland
Posted by O Suave Gigante on 2016-08-16 16:48:16
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