What is this in the river?

[SDHNTR]

Part of a gaging station to measure CFS? A salmon/fish counter?

 

[MudBugVa]

Looks like an a PIT tag array for monitoring fish movement. Basically the fish have an RFID implanted in them and when they cross the array/antenna that individuals movement gets logged. Similar to the easy-pass or fast-track RFID used for toll roads.

 

[SDHNTR]

That would make sense. There is a hatchery a few miles upstream.

 

[blicero]

I helped out with an electroshocking project on a river here (Northern Colorado). They electroshocked about 2 miles of river to collect all the brown trout, tagged them with RFIDs, and then relocated them downstream like 10 miles or something.

Their intent was to stock whirling disease resistant rainbows in that stretch instead, and they wanted to get the browns out so they wouldn't compete for resources.

Last time I fished that stretch, the only thing I caught were browns, so I don't think it worked, but I'd bet your contraption in the river is for a similar purpose.

 

[TheTone]

Looks like an a PIT tag array for monitoring fish movement. Basically the fish have an RFID implanted in them and when they cross the array/antenna that individuals movement gets logged. Similar to the easy-pass or fast-track RFID used for toll roads.

This is the right answer