Putting two together

On a recent visit to the Robles Fish Passage Facility in Southern California we noticed that Casitas Municipal Water District (CMWD) had enhanced their VAKI Riverwatcher system. Not only had they constructed an impressive crane to hoist the Riverwatcher and passage chute in and out of the fish ladder, they had also fitted their passage chute with a Passive Integrated Transponder (PIT) tag antenna. A PIT tag is a small radio transponder that will transmit a unique identification code when it is within range of an antenna sending out the correct radio frequency. We recently described a supersized PIT tag antenna array that we designed and constructed for diversion tunnel. When a fish carrying a PIT tag swims through the passage chute at the Robles facility, it isn’t just counted, measured and video taped, it also transmits valuable information about its past. Using the unique identification number, the fisheries biologists at CMWD can determine when the fish was tagged, what size it was when it was tagged, where it was tagged, when it was last detected and other relevant information.  It is always interesting to see how others have set up their fish counting devices, and the dual Riverwatcher-PIT tag system seems like a valuable asset.