Importance of Natural Resources

How to Count Fish in a Creek

We want to know how many fish are in
this part of the creek. This is how we do it. First, we put nets upriver and
downriver to pen the fish within the reach. We’ll go over some safety rules,
and then someone puts on the backpack electrofisher, which generates 25 watts
of energy in the ring. We’ll walk in the stream and use the electrofisher to
stun nearby fish which gives us a few seconds to catch them. Did you see the
two fish? Try it again but this time in slo-mo. We sometimes find other critters
that aren’t fish like the salamander and we’ll put them in a separate bucket so
that they don’t get collected again. Then we’ll count identify and measure the
fish. We only caught green sunfish this time, except for this goldfish. Hmm wonder how he got there… We’ll then fish the same part of the creek two more times.
Then we’ll use the Leslie method for estimating populations by depletion to
estimate how many fish are in this stretch of the creek, based on how many
fish we caught on each pass. Today’s estimate is about 160 fish! Then all the
fish are released back into the river after the brief stay in spa bucket. And
that’s how we measure nature.

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