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Re: Electroshock procedures


Glenn Parsons <[log in to unmask]>


Academic forum on fisheries ecology and related topics <[log in to unmask]>


Wed, 4 Dec 1996 08:11:58 -0600





text/plain (1 lines)

Fish Folk,

I have a question that is related to the discussion of electrofishsing. We
use electroshocked crappie (Pomoxis annularis and P. nigromaculatus) for
strip spawning
in my lab. Is anyone aware of any effects of electroshock on egg viability,
that is, could our problems with successfully strip spawning crappie be due
to the fact that the female was electroshocked?

Glenn Parsons
University of Mississippi
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>>Date: Mon, 2 Dec 1996 14:40:55 -0800
>>From: Craig Fusaro <[log in to unmask]>
>>Subject: Electroshock procedures
>>"Do (sic) to the irregular or rocky conditions electrofishing may be
>>required... Fish will be collected using pulsed direct current with
>>voltage set at 200-300 volt and 0.1 to 2.0 amps output... Pulse frequency
>>and pulse width will be set to induce involuntary swimming action with
>>minimum harm to fish."
>>1. Is electrofishing really effective in five to ten foot water depth?
>>2. Are the pulse voltage and current settings specified appropriate for
>>these water depths?
>>3. Would mortalities reasonbly be expected under the regimen described
>>above, and, if so, what could be expected in terms of percent deaths?
>Pulsed direct current electrofishing from a boat is definitely the safest
>method from the fish's point of view. We have had considerable success
>using our boat-mounted electroshocker (Model 7.5 GPP, Smith-Root, Vancouver,
>Washington) in river water 5-10 feet deep. In fact we were pulling 6-8 lb
>steelhead out of the Columbia River a couple of years ago. The key to
>effective electrofishing is knowing the conductivity of the water you will
>be fishing. We have fished with 900 W (300 volts at 3 amps) without any
>significant mortality to larger fish. Keep in mind, however, that many of
>the potential adverse effects of electrofishing are manifested over a
>relatively long period of time. Since most of our work has been
>catch-and-release, we have been unable to calculate a true mortality rate.
>Good luck!
>Tad Deshler
>Tetra Tech, Inc.
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