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

Abstract

The use of mobile radio frequency identification (RFID) systems to detect PIT tags has increased in support of research on fish movement, population dynamics, and habitat use. We describe the development and application of a mobile RFID system that incorporates GPS to detect PIT‐tagged fish and evaluate habitat utilization in streams. The study was conducted in two distinct phases. First, development and testing of the RFID–GPS system were conducted using georeferenced, PIT‐tagged rocks to evaluate detection probability and GPS accuracy. Second, the system was field deployed to estimate the abundance of PIT‐tagged fish and evaluate habitat utilization. Detection probability was negatively influenced by stream width, distance from the stream center, and water depth, whereas detection probability increased with the number of passes. The GPS error between detected and surveyed positions averaged 4.5 m, with greater error observed in longitude than in latitude. Because of high capture and recapture probabilities, abundance estimation of PIT‐tagged fish was not only possible but also relatively precise. All detections during field deployment were assigned habitat types using the “intersect,” “closest,” and “buffer” methods in ArcGIS. Analysis of habitat utilization was limited to two bedform classes, riffles and pools, because the average area of runs and glides was smaller than the average GPS error. More Brown Trout Salmo trutta were detected in pools (76–80%) than in riffles, and all Rainbow Trout Oncorhynchus mykiss and cutbow trout (Cutthroat Trout O. clarkii × Rainbow Trout) were detected in pools. The detection field covered more cross‐sectional area in pools than in riffles, which could have influenced the analysis of habitat utilization. The influence of GPS error on habitat evaluations will depend on stream size, as erroneous habitat associations should diminish as stream size increases. The flexibility of the RFID–GPS system makes it useful for a variety of studies related to habitat utilization, fish migration, and population trends. Received March 31, 2017; accepted August 19, 2017 Published online October 20, 2017

Keeping it classy: classification of live fish and ghost PIT tags detected with a mobile PIT tag interrogation system using an innovative analytical approach

“…Data are from the San Juan River study area in 2016 and 2017. Mobile PIT tag interrogators have been developed to supplement low recapture rates and reduce negative effects of capture and handling of organisms (Paukert et al 2005;Hunt et al 2012;Reynolds et al 2012), but the inability to separate ghost tags from live fish based on detection data are one of the recurring points of discussion in studies using mobile systems (e.g., O'Donnell et al 2010;Fetherman et al 2014;Richer et al 2017). Extensive use of PIT tags has led to large numbers of potential ghost tags in aquatic systems, and in other work, extensive movement of ghost tags has been observed (from 2.0 km in Bond et al 2019 to 4.1 km in Stout et al 2019), which highlights the need for a classification system.…”

“…However, PIAs rely on the fish swimming past a fixed point, which can limit the numbers of fish detected to fish that are inclined to move (Snook et al 2016). Different forms of mobile PIT tag antennas (Fischer et al 2012;Hodge et al 2015;Richer et al 2017) have been created to address some of the limitations of PIAs.…”

“…While the mobile PIT tag antennas can improve detection probability, increase spatial coverage of PIT tag sampling, and answer questions about habitat association, there are limitations and analytical issues to be resolved. In other studies where mobile PIT tag antennas have been used (Fetherman et al 2015;Richer et al 2017), an emerging concern is the prevalence of ghost tags. Ghost tags are created when tag loss, predation, and natural mortality leave a PIT tag in the environment (O'Donnell et al 2010).…”

We Ain't Afraid of No Ghosts: Tracking Habitat Interactions and Movement Dynamics of Ghost Tags under Differing Flow Conditions in a Sand‐Bed River

“…The use of PIT tags has increased dramatically since their introduction, in part because of the relatively low cost of the tags. Passive integrated transponder tags have been used widely to explore fish behavior (Fetherman et al 2015), describe habitat use (Bottcher et al 2013;Conner et al 2016;Richer et al 2017), quantify movement patterns (Zydlewski et al 2001;Homel and Budy 2008;Cathcart et al 2018), assess fish passage (Lokteff et al 2013;Pennock et al 2018;Baker et al 2019), estimate survival (Osmundson and Burnham 1998;Budy and Schaller 2007;Conner et al 2015), and estimate abundance (Fetherman et al 2015;Richer et al 2017). Collaborations across spatial scales and the creation of databases to share data allow for the tracking of fish beyond individual study goals.…”

“…Boat-mounted antennas have been used to survey mussels in non-wadeable habitats (Fischer et al 2012), and backpack antennas have been used to sample fish in wadeable streams (Hill et al 2006;O'Donnell et al 2010;Hodge et al 2015). Some systems combining a PIT tag interrogation system with a raft and GPS unit have been developed (Fetherman et al 2014;Richer et al 2017), with the ability to cover long reaches (>5 km). Our system, the PIT Portable Antenna System (PITPASS), is capable of floating much greater distances (>32 km in 1 d depending on flows).…”