8171

• UCREFRP Catalog Number: 8171
• Author: U.S. Fish and Wildlife Service.
• Title: A Study to Determine the Biological Feasibility of Pit Tags for Endangered Fishes in the Upper Colorado River Basin.
• USFW Year: 1990.
• USFW - Doc Type: Grand Junction, Colorado.
• Copyright Material: NO

one that might reduce or eliminate the problems associated with previous tagging and
identification systems used for these fishes.
In 1987, the Grand Junction station of the Colorado River Fishery Project (CRFP)
began studies to evaluate the passive integrated transponder (PIT) tag. The PIT tag is a
cylindrical, glass-encapsulated tag (about 11 mm X 2.1 mm) that can be implanted or
attached. The tag is completely passive, does not emit energy, and is activated by an
external electromagnetic exciter that transmits a uniquely identifiable signal. This signal
is detected by the exciter and decoded by a reader device.
This tag has been used for Pacific salmon (OncorhUchus spp.) (Prentice et al.
1987) and largemouth bass (Micropterus salmoides) brood fish (Harvey and Campbell
1989 with promising results. Salmon smolts (65 mm) have been successfully PIT tagged
with minimal (0.5%) mortality and high (99%) tag retention (Scott McCutcheon,
personal communication). Initially developed to identify livestock, the PIT tag has great
potential for marking Colorado River endangered fishes if proven biologically
compatible. However, before PIT tags could be implemented as identification markers
for endangered fishes in the UCRB, it was felt prudent to experimentally evaluate the
tags and associated sensing and decoding equipment in a controlled environment. Its
miniature size makes it probable that this tag could be implanted in endangered fishes as
small as 100 mm. This tag could be essential to integrated operations involving wild and
hatchery stocks, brood fish management, production, experimental augmentation,
monitoring, and recovery.
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