What do your pet and my study fish have in common?

By Patrick Cooney

Question: What do Jackson, my mutt dog, and my research fish all have in common?

Besides both being incredibly photogenic,
what do Jackson and this Brook Trout have in common?

Answer: They are all implanted with Passive Integrated Transponder (PIT) tags that transmit a unique identification number when exposed to a magnetic field.  Jackson is tagged so that a veterinarian can help him get back home if he is lost, but why would PIT tags be used in fish?

PIT tags are small microchips
used to track individual animals.

Developed originally to track cattle on farms, PIT tags are now being used in animals, like my fish, for research purposes.

Being able to identify individual fish from the rest of a population can reveal vast amounts of knowledge.  For example, if I know the length and weight of a fish at the time of tagging, I can then recapture, reweigh, and remeasure the fish at a later date, allowing me to know the growth of that fish over the given time period.

Another common use of PIT tags in fish, besides growth determination, is monitoring of movement and survival.

An antenna used to monitor the
movement of PIT tagged trout.

Freshwater fisheries biologists are constructing passive antennas at dams and along river bottoms.  As PIT tagged fish swim over or through these antennas, the unique identification number is received and recorded along with a time stamp on a computer on shore allowing the researcher to know how far the fish has moved.

Fisheries biologists are also developing and using active antennas that float on the water surface and attach to a raft to paddle downstream to determine the types of habitat that fish are selecting (see picture at end of article).

The use of this technology to understand the movements and migrations of fish in rivers and at dams, as well as the types of habitats that fish select, is revolutionizing the decisions being made for the long term viability of fisheries across the globe.

Examples of projects where PIT tags are being used:

● Vast numbers of salmon in the Pacific Northwest of the United States are implanted with PIT tags to help understand the impacts of dams on fish migration (link).

A sturgeon being PIT tagged.

● Striped Bass on the East Coast of the United States are being PIT tagged to help determine reporting rates of reward tags by commercial and recreational anglers (link).

● Gulf Sturgeon can live as long as humans, and are being PIT tagged from Mississippi to Florida to help determine movement and population sizes (link).

● Mountain trout are being tagged in North Carolina to determine trout movement, survival, and habitat selection to help optimize the trout stocking program.

For an in depth look at how PIT tags and associated antenna technologies work, please see this link.

'Like' the photos and links from The Fisheries Blog on Facebook and Twitter.

Last weeks post: What are more important, cruise ships or coral reefs?  You decide.

A floating PIT tag antenna used to determine trout habitat selection.