RE: NANFA-- Collecting Equipment - electrofishing

Dave Neely (
Tue, 11 Jan 2000 22:00:09 CST

>'Course that doesn't address the question of how electrofishing >compares
>to seining, dipnetting or castnetting. I almost never use >traps, because
>I have limited time at the site and I want to get in >and see what's there
>right now. I can see how fishes in a trap >could become stressed and
>injured while trying to escape over a long >period. If I'm careful, I
>usually have very low mortality on netted >fishes.

Agreed. Some fish taxa are much more vulnerable to electrofishing than
others, and are hit harder (many catostomids and percids have a higher
mortality rate). This does not seem to be entirely a function of size-
obviously the larger the fish, the larger the field they generate across
their body (depending upon the wavelength/frequency being generated). Often
small cyprinids will swim right through a field that would stun larger fish,
seemingly without adverse effects. When using electrofishing gear, you need
to be VERY aware of what taxa you are likely to encounter, and if that means
running a lower voltage/frequency in areas with sensitive taxa (and
sacrificing efficiency), then so be it.

I'm somewhat skeptical of their results, especially given the lack of proper
experimental methods. Having used just about everything from cyanide to boat
shockers to gill nets to slurp guns, I'd hypothesize that the most critical
thing to reduce mortality is to reduce handling time. Period. That said,
this would be a good excuse to do some fun experimental science, if anyone
is interested...


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