Fish and Wildlife Service

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Tagging/Marking of Fish

Currently the Center uses four different methods. These methods are used as an identification tool. Biologists both in the field and on-site are able to identify fish that are reared at a facility versus those that are wild:

Calcien Marking: Immersion fluorescent marker that adheres to boney parts of the fish. The fins and cranium seem to be the most susceptible parts of the fish. When placed under blue light, the marked areas exhibit fluorescence.
Visible Implant Elastomer (VIE): Colored fluorescent elastomer material is injected into tissue with a hypodermic syringe. The material then cures into a pliable, solid well-defined mark, which fluoresces under blue light.
Passive Integrated Transponder (PIT): Small microchips (about the size of a grain of rice) that are injected with a hypodermic syringe and read with a hand-held scanner.
Wire Tagging: The Mark IV Tagging device emits a small magnetic wire tag that is injected just below the surface skin in various locations on the fish. Tags are read using a hand-held wand detector.

Tagging/Marking sessions are coordinated in advance; volunteers, sister agencies and staff tag/mark over 150,000 endangered & threatened fish per year. Some fish remain on station while others are transported and returned to their natural habitat.

Last updated: July 17, 2008