Efficacy and accuracy of portable PIT-antennae when locating fish in ice-covered streams

• Published in: Hydrobiologia
• Main Authors: Linnansaari, Tommi, Roussel, Jean-Marc, Cunjak, R.A., Halleraker, J.H.
• Other Authors: Canadian Rivers Institute and Department of Biology, University of New Brunswick (UNB), Écologie et santé des écosystèmes (ESE), Institut National de la Recherche Agronomique (INRA)-AGROCAMPUS OUEST, Stiftelsen for INdustriell og TEknisk Forskning Digital Trondheim (SINTEF Digital)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2007
• Subjects: HIVER; GLACE; TRANSPONDER; PIT; JUVENILE; EXACTITUDE; EFFICACITE; salmon; atlantic; measurement; saumon de l'atlantique; salmo salar; rivière; méthode de mesure; [SDV]Life Sciences [q-bio]; Salmo salar
• Online Access: https://hal.science/hal-01453631; https://doi.org/10.1007/s10750-006-0546-9

Active tracking of passive integrated transponder (PIT)-tags using portable antennae is becoming an increasingly common technique in fish habitat studies in shallow rivers. We carried out “blind testing” to test the efficacy (% tags found) and accuracy (distance between predicted and true tag location) of a portable antenna system (Texas Instruments) in winter conditions using 23-mm PIT-tags. Up to 90 cm reading range was achieved and signals penetrated ice, rock, wood and water. In the “blind test” trials, a majority of the hidden tags (N = 12–30) were found indicating high tracking efficacy. PIT-tags that were oriented with their cylindrical axis parallel to the plane of the antenna coil inductor loop resulted in a bimodal detection field that had low detection range in the centre of the loop. The utilization of this bimodal detection field proved to be a very accurate method for identifying tag position (mean ± SE distance from predicted to true tag location 10.9 ± 1.4 cm) and thus well suited for microhabitat and activity studies in winter conditions. Aggregations of tags (multiple tags within 1 m2) and obstacles for the antenna maneuvering (e.g., boulders, logjams) reduced the pinpointing accuracy (mean ± SE 13.3 ± 1.8 cm), but the reduction in accuracy was statistically non-significant between the single and aggregated tags.