Summary: Hydrobiologia 371/372: 4752, 1998.
J.-P. Lagard`ere, M.-L. B´egout Anras & G. Claireaux (eds), Advances in Invertebrates and Fish Telemetry.
© 1998 Kluwer Academic Publishers. Printed in Belgium.
A dynamic combined acoustic and radio transmitting
tag for diadromous fish
G. H. Niezgoda1, R. S. McKinley2, D. White2, G. Anderson2 & D. Cote2
1 Lotek Marine Technologies Inc, 114 Cabot Street, St. John's, NF A1C 1Z8, Canada (email@example.com)
2 Waterloo Biotelemetry Institute, Department of Biology, University of Waterloo, 200 University Av. W., Waterloo,
ON N2L 3G1, Canada
Key words: diadromous, conductivity, bio-telemetry, estuary, CART
A combined acoustic and radio transmitting (CART) tag employing a dynamic conductivity switch suitable for
investigating the migratory behavior of diadromous fish is described. The unique feature of the transmitter is its
ability to sense the electrical conductivity of the ambient water and therefore operate in the appropriate signal
mode. Under fresh water conditions the transmitter operates in radio mode; in sea water it operates in acoustic
mode. To optimize range performance the conductivity threshold setting at which the tag switches mode can be
changed to suit the application. This paper describes a proposed criterion for threshold selection, the physical probe
characteristics and the recommended tag attachment procedure.