Passive Integrated Transponder
(PIT Tag)The PIT tag consists of a small glass-encapsulated electromagnetic coil and microchip. The smallest full-duplex PIT tags can be inserted into the body cavity of a fish using a veterinary syringe and the slightly larger half-duplex PIT tag can be surgically inserted into the body cavity. The tag does not contain a battery and is inert until an inductive pulse is sent by the antenna/reader. When the tag has charged, it responds with a short radio message that contains the unique serial number. Tags are available as read-only tags containing unique factory set alpha-numeric code or as read-write tags that can be changed to any value. Tag readers can consist of a hand held wand, pass through antenna, or even a plate that can be placed on the bed of a stream.
Advantages:
- Can identify individuals as well as groups
- Tags can last through the life cycle of fish
- Can be detected and decoded in fresh and salt water
- Data from the tag can be recovered without the need to anaesthetize, handle, restrain or kill the fish
Disadvantages:
- Fish must pass close to antenna/reader for data to be detected