One of my more fun days in the field recently was doing fish surveys...tromping around in Goose Creek armed with a backpack shocker, net, and bucket. As part of a management indicator species monitoring program, we were tasked with capturing and identifiying the fish present in a creek on our forest. Managers want to know what kind and how many fish there are, specifically how many are native and how many are exotic. This can help them determine the health of native fish populations and help indicate environmental conditions.
Two 'shockers' are outfitted with backpack shocking units while everyone else is strategically placed in the creek, ready to pounce on the the fish. An electric 'wand', of sorts, probes the water, sending out an electric current that temporarily stuns fish and makes them float to the surface. Fish are netted and put into live wells until they are ready to be processed.
Once the stream has been sufficiently shocked, the fish are worked over, and we collect important biological information such as species, size, weight, age, etc. The entire process is a slime fest, but great fun, and very informative. After data collection, fish are released back into the creek to finish out their happy little fish lives.