Things happen in the field, particularly when we are using complicated sampling gears (= electrofishing equipment).  Malfunctions can occur in the electrodes, branch circuits (conductors running from the control box or power source to the electrodes), the power source, or the control box.  Biologists build a lot of their own equipment, wiring boats, electric seines, and the like.  From what I’ve seen, most problems appear in our wiring or construction, but generator problems, and sometimes control box issues do occur.  Fisheries biologists are a resourceful lot.  If given direction, they usually can diagnose the problem at hand and get back to sampling.  With this in mind, Midwest Lake Electrofishing Systems, based in Polo, Missouri, has developed a list of items for a basic field tool kit (see below).  Although the intent is a tool kit for electrofishing boats, this kit applies to any electrofishing gear type.

Many thanks to the crew at MLES.

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In Part A of this blog, it was calculated from a lab study that the effective conductivity of Grass Carp was 62 uS/cm. In Part B, let me show you a simple way of using that information in the field to improve the capture success of Grass Carp based on those results. You may want to download the Electrofishing Tool or App from the Tool section of this site.

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What is your electrofisher ammeter telling you? The obvious answer is that it is indicating amperes of electrical current flow, the movement of electrical charges past a point or surface. But not all electrofisher ammeters display the same measure of current, and that can and does lead to confusion.

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Sometimes, things just don’t work as expected. You go to a new sampling site, determine ambient water conductivity, estimate a good starting point for standardizing by power and conduct a quick pretrial to fine tune the voltage, current or power levels for successful fishing.  But, either the starting point is incorrect, or the sampling begins successfully and then something changes to reduce effectiveness.  Below are three examples of unusual circumstances in electrofishing.  Two of these were my direct experiences; the other was reported to me.Continue Reading..

Jim Reynolds and I just taught a boat electrofishing course in Redding, California at Whiskeytown Lake. That provided some threshold fishing data for voltage, current and power for each of four electrofishing boats. One can standardize by power using any of the three parameters. Which parameter is less variable among a fleet of boats?

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Electrical fields around electrofishing anodes are critical to fish capture effectiveness. The size, shape and intensity of those electrical fields are determined by the anode design and deployment in the water as well as by the electricity applied to them.  There were two main questions to answer in this little study: (1) Could accurate electrical measurements be made from approximately ¼ scale model electrodes in a small body of water, and (2) Would those measurements provide useful information about the effect of anode ring size on their electrical fields?

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Dr. Alan Temple posted a blog on December 9, 2015 entitled “Setting Doses for Lab Experiments.” He suggested that I submit a blog on other aspects of lab studies in tanks. This blog covers the setup of tank studies for electrofishing research, and I plan to submit a companion blog on procedures for tank studies. Important aspects to consider for lab studies are the test tank, the electrodes, the power supply and the electrical field.

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Here’s a few pics of electrofishing porn from the American Fisheries Society meeting in Portland, OR, 2015. Lots of new goodies. Enjoy!

Most boat electrofishing pulsators (control boxes) are powered with portable generators that provide 240-V, single-phase AC. These generators are available from common commercial sources such as hardware stores or electrical supply houses. (Note: a notable exception is the GPP pulsator made by Smith-Root, Inc., that requires a specially-constructed generator; it will not be discussed further here.) This short blog explains the electrical outlet of a generator, how to test for the safety of a generator if used for boat electrofishing, and what to do if the test indicates that a generator is not safe for electrofishing.

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Electrofishing is a primary sampling method for near-shore fish species in lakes and rivers, and for fish species and assemblages in streams. We must admit, however, that it is a sampling technique with inherent risks. People, water and electricity are in close proximity. This blog describes the potential for human injury or death if someone falls into water having an electrical field. It specifically involves boat electrofishing, but the same idea can be used for tow/push barges, shore-based units and backpack electrofishing.Continue Reading..