Raft and Floating Radio Frequency Identification (RFID) Antenna Systems for Detecting and Estimating Abundance of PIT‐tagged Fish in Rivers

Abstract

Portable radio frequency identification (RFID) PIT tag antenna systems are increasingly being used in studies examining aquatic animal movement, survival, and habitat use, and their design flexibility permits application in a wide variety of settings. We describe the construction, use, and performance of two portable floating RFID PIT tag antenna systems designed to detect fish that were unavailable for recapture using stationary antennas or electrofishing. A raft antenna system was designed to detect and locate PIT‐tagged fish in relatively long (i.e., ≥10 km) river reaches, and consisted of two antennas: (1) a horizontal antenna (4 × 1.2 m) installed on the bottom of the raft and used to detect fish in shallower river reaches (<1 m), and (2) a vertical antenna (2.7 × 1.2 m) for detecting fish in deeper pools (≥1 m). Detection distances of the horizontal antenna were between 0.7 and 1.0 m, and detection probability was 0.32 ± 0.02 (mean ± SE) in a field test using rocks marked with 32‐mm PIT tags. Detection probability of PIT‐tagged fish in the Cache la Poudre River, Colorado, using the raft antenna system, which covered 21% of the wetted area, was 0.14 ± 0.14. A shore‐deployed floating antenna (14.6 × 0.6 m), which covered 100% of the wetted area, was designed for use by two operators for detecting and locating PIT‐tagged fish in shorter (i.e., <2 km) river reaches. Detection distances of the shore‐deployed floating antenna were between 0.7 and 0.8 m, and detection probabilities during field deployment in the St. Vrain River exceeded 0.52. The shore‐deployed floating antenna was also used to estimate abundance of PIT‐tagged fish. Results suggest that the shore‐deployed floating antenna could be used as an alternative to estimating abundance using traditional sampling methods such as electrofishing. Received December 19, 2013; accepted July 1, 2014

Incorporating GPS and Mobile Radio Frequency Identification to Detect PIT‐Tagged Fish and Evaluate Habitat Utilization in Streams

“…The use of PIT tags to estimate fish growth, movement, and mortality has become an important tool for biologists due to their relatively low cost, longevity, ability to identify unique individuals, ease of application, and minimal effects on fish survival, growth, feeding behavior, and swimming performance Newby et al 2007;Ficke et al 2012). Radio frequency identification (RFID) systems have been used in small, wadeable rivers to detect PIT-tagged fish via both stationary (Horton et al 2007;Connolly et al 2008;Fetherman et al 2015;Ficke 2015;Fox et al 2016) and mobile designs (Roussel et al 2000;Cucherousset et al 2005;Hill et al 2006;Lokteff et al 2013;Fetherman et al 2014;Holmes et al 2014;Hodge et al 2015). Stationary antennae have been used to analyze fish survival and movement patterns in rivers (Compton et al 2008;Connolly et al 2008;Fetherman et al 2015) and to examine habitat use on inundated floodplains (Conrad et al 2016).…”

“…Mobile RFID systems have been used to analyze fish survival, movement, and habitat utilization. Fetherman et al (2014) deployed river-spanning mobile antennas to estimate abundance and determine the fate of PIT-tagged fish within relatively short river reaches (<2 km) and used raft antennas to determine the location and fate of PIT-tagged fish in longer river reaches (>10 km). Holmes et al (2014) synchronized a mobile RFID system with GPS to evaluate fish emigration and mortality in a New Zealand headwater tributary, and RFID-GPS systems are being applied to evaluate vital rates for endangered fishes in the San Juan River, Utah (M. McKinstry, Bureau of Reclamation; P. MacKinnon, Utah State University; and B. Stout, Utah State University, unpublished data).…”

“…Application of RFID studies in streams can be limited by a number of factors, including damage to arrays during floods (Holmes et al 2014), antenna distortion (Ficke 2015), tag loss, predation, and site access. The detection efficiency (detection probability) for stationary and mobile arrays can be affected by stream discharge, tag size, tag orientation, power source, proximity to other antennae Fetherman et al 2014), tag collision (Axel et al 2005;O'Donnell et al 2010), and electromagnetic interference (Greenberg and Giller 2000;Bond et al 2007;Horton et al 2007). Hodge et al (2015) utilized a backpack PIT tag detector with internal GPS (manufactured by Biomark) and suggested that the utility of that system in mountain streams might be limited to lowflow, ice-free seasons and relatively small study reaches due to limited detection distance and time constraints.…”

“…Retention rates of PIT tags are highly variable and can be influenced by tagging location; tagger experience; and the age, size, sex, and species of the tagged fish (Bateman et al 2009;Dieterman and Hoxmeier 2009;Meyer et al 2011;Ficke et al 2012). Failure to account for ghost tags can lead to incorrect interpretations regarding fish location and fate (Fetherman et al 2014). Regardless of these limitations, RFID technology provides a variety of useful applications for both fisheries research and management.…”

Application of Passive Integrated Transponder Technology to Juvenile Salmon Habitat Use on an Experimental Agricultural Floodplain

“…Innovations that apply PIT technology, such as the recent design for floating raft antennas (Fetherman et al 2014), will continue to be critical for evaluating salmonid use of off-channel habitats. The seasonal use of agricultural land for salmon nursery habitat is just now beginning to be investigated, and small PIT tags can be useful for evaluating the viability of this land as habitat, including the potential for increased contaminant and predation exposure.…”