Field Tool Kit


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.


To Kill a Fish Egg

How much electricity does it take to kill a fish egg, or unhatched embryo? We have mentioned that in classes but have only discussed it in generalities. The purpose of this blog is to look more closely at the question and to quantify it as best we can with the limited information available. It makes sense to look at this from the perspective of egg, or embryo, diameter. Bohl et al. (2010), Electroshock-induced mortality in freshwater fish embryos increases with embryo diameter: a model based on results from 10 species, Journal of Fish Biology 76:975-986 is the source of information for this investigation.

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New Boat Pulsator seen at Kansas City AFS Meeting

While attending the Annual Meeting of the American Fisheries Society in Kansas City in August, I visited the vendors, especially the electrofisher manufacturers. It is good to visit with those I know and to see new products. I don’t attend a lot of such meetings, but this was the first time for me to see a booth by ETS Electrofishing Systems LLC.  Burke O’Neal of ETS Electrofishing retired and sold the company to his sons.  Mark O’Neal now operates the company, which had a slight name change, and moved it to Madison Wisconsin. Burke and I never met, though we had corresponded by email and had talked on the phone over the years. We even collaborated on some testing of voltage gradient probes and of backpack electrofisher anodes.  In August, it was my privilege to meet Mark.

ETS now manufacturers an 82 peak amp, high-conductivity version called the MBS-82. It is an upgrade from their former 72-amp high-conductivity version and also has a larger internal circuit breaker. The 82-amp version has been their standard high-conductivity model since August 2015. The new development is a high-voltage version for use in lower conductivity water. This new version, which was in beta format for the AFS meeting, has three voltage ranges – 1000, 600 and 300 volts – to cover a very wide range of water conductivity.  The expected current outputs were reported as 30, 40 and 82 peak amps for the 1000, 600 and 300 volt ranges, respectively. While advertised performance is somewhat informative, I wanted to see actual performance data. So, I talked Mark into doing some extensive testing of his new unit over a wide range of resistance to simulate a wide range of water conductivity. This blog shows those results.

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