A Portable System for Reading Large Passive Integrated Transponder Tags from Wild Trout

Abstract

This paper describes a system based on a commercial portable energizer-reader module and antennas and a hand-held programmable calculator for reading large (4 ϫ 23 mm and 4 ϫ 32 mm) passive integrated transponder (PIT) tags. Maximum tag-reading distances in water were 45 cm for ferrite-core stick antennas and 86 cm for a loop (gate) antenna; these distances varied with the size of the tags and their orientation to the antennas. The tags, tested on wild brown trout Salmo trutta and wild rainbow trout Oncorhynchus mykiss, were either inserted into the peritoneal cavity with a hypodermic needle or attached externally at the base of the dorsal fin with a fish hook and monofilament line. The fish were held in artificial channels 1 m wide and 50 m long and in two 3-4 m-wide stream sections, one 70 m long and the other 90 m long. During a 5week period we were routinely able to detect marked fish by (1) walking along the channels and stream sections probing the water with an antenna, and (2) by positioning antennas on the substrate of the channels and recording tags from undisturbed fish as they swam by. We did not conduct a formal study of the long-term suitability of either type of tag placement or of the overall efficiency in detecting marked fish.

Evaluation of Fish Movements, Migration Patterns, and Population Abundance with Streamwidth PIT Tag Interrogation Systems, Final Report 2002.

“…This allowed the researcher to avoid the many possible negative impacts of electrofishing and particularly the higher probability of mortality and injury associated with repeated electrofishing (Gatz et al 1986;Mesa and Schreck 1989). Backpack efficiencies were within previously identified levels for other portable PIT tag detection units, 25 -84% (TI systems, Morhardt et al 2000;Roussel et al 2000;Zydlewski et al 2001). The rate of scanning was based on the feasibility of scanning the entire creek within a two week period.…”

“…Morhardt et al (2000) first suggested the use of pass-through PIT tag antennas (for detection of 23 mm tags) for streams up to 4 m across because of the increased detection range of PIT tags antennas oriented upright (pass-through) versus when they were laid flat on a stream bed (flat plate design: Armstrong et al 1996). Zydlewski et al (2001) were the first to apply the pass-through design in a natural stream 8 m in cross section and achieved detection efficiencies averaging 93%.…”

“…Several studies have presented the use of portable PIT tag detectors for gathering recapture and habitat use information without having to physically capture the fish (Morhardt et al 2000;Roussel et al 2000;Zydlewski et al 2001). This method affords the advantage of not physically harming the fish from repeated electrofishing (Gatz et al 1986;Mesa and Schreck 1989).…”

Assessment of PIT tag retention and post-tagging survival in metamorphosing juvenile sea lamprey

“…Tags are implanted in individual fish and can be read with a handheld scanner or remotely when the fish passes an electromagnetically charged antenna [11,12]. Antennas can be designed to encompass cross sections of a stream and detect tagged individuals that pass the antenna array without physically recapturing the fish [13,14]. Antennas can be constructed to withstand high discharge events and periods of high debris loading that would be likely to dislodge or destroy other sampling gear [12,15,16].…”

Development and evaluation of portable PIT tag detection units: PITpacks

“…Portable PIT tag detection systems were also developed to allow operators to scan wadable waters in search of fish (Morhardt et al, 2000;Roussel et al, 2000;Zydlewski et al, 2001;Cucherousset et al, 2005;Quintella et al, 2005). These portable PIT systems are advantageous because they provide a relatively non-invasive method to assess spatial distributions of local populations, fine-scale movement and microhabitat preferences of individuals, without repeat handling.…”