The performance and efficacy of a two‐person operated portable PIT‐antenna for monitoring spatial distribution of stream fish populations

• Published in: River Research and Applications
• Main Authors: Linnansaari, Tommi P., Cunjak, Richard A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2007
• Subjects: Atlantic salmon
• Online Access: http://dx.doi.org/10.1002/rra.1003; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Frra.1003; https://onlinelibrary.wiley.com/doi/pdf/10.1002/rra.1003

Abstract Passive Integrated Transponder (PIT) technology has enabled the tracking of individual fish by using data‐logging stations and one‐person operated portable tracking units. Whereas data‐logging stations are fixed at a certain location, the portable units have traditionally been used in studies that require tracking operations at small spatial scales (<1000 m 2 ) due to the time investment necessary to fully scan the stream channel. We developed a two‐person operated portable antenna that is stretched between the operators and the area in between is scanned for PIT‐tags. The antenna was five metres wide but can be customized to fit stream‐specific needs. The antenna can be used with existing Texas Instruments Series 2000 tracking units, and the detection distance ranged between 46 and 61 cm when using 23‐ or 32‐mm PIT‐tags, respectively (tag held parallel to the plane of the open coil inductor loop). To assess antenna performance in field trial, we compared the efficacy (% tags found) and time‐efficiency (time used to track a study site) between one‐ and two‐person antennae in three separate stream sites. The new antenna type proved to be very efficient (95.2–100%) for locating tags in all trials. However, the new antenna type might not perform adequately in areas with high structural complexity (e.g. logjams, overhanging vegetation) and a follow‐up with one‐person operated antenna is recommended in such complex habitats. The time consumption was always lower (10–53%) with the new antenna and significant time savings can be assumed especially in areas with a low density of PIT‐tagged individuals. Further, we have successfully used the new antenna type to track juvenile Atlantic salmon both in winter conditions (ice‐free) and warmer water (14°C) without causing fright responses. The new antenna type makes the use of PIT‐technology feasible not only at the micro/mesohabitat scale but also at the segment/reach scale and can thus be used to monitor behavioural responses of fish at the population level in ...