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 go over some safety rules and then someone puts on the backpack electrofisher, which generates 25W 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 this salamander, and we’ll put them in a separate bucket so 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 fish are released back into the river after their brief stay… in spa bucket.   

And that’s how we measure nature.

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