Patterns of fish movement at a desert river confluence

Abstract

Quantifying fish movements in river networks helps identify critical habitat needs and how they change with environmental conditions. Some of the challenges in tracking fish movements can be overcome with the use of passive integrated transponder (PIT) tagging and antennas. We used PIT technology to test predictions of movement behaviour for four fish species at a mainstem-tributary confluence zone in an arid-land river system. Specifically, we focused on the McElmo Creek tributary confluence with the San Juan River in southwestern Utah, USA. We quantified variation in species occurrences at this confluence zone from May 2012 to December 2015 relative to temporal and environmental conditions. We considered occurrences among species relative to tagging origins (tributary versus mainstem), season and time of day. Generally, fishes tagged in the focal tributary were more likely to be detected compared to fish tagged in the mainstem river or other tributaries. Additionally, adults were most likely to be detected across multiple years compared to subadults. Based on a Random Forests model, the best performing environmental variables for predicting seasonal detections included mainstem discharge during run-off season (razorback sucker Xyrauchen texanus), tributary discharge during monsoon season (Colorado pikeminnow Ptychocheilus lucius) and mainstem water temperature (flannelmouth sucker Catostomus latipinnis and channel catfish Ictalurus punctatus). The variable responses by endemic and introduced fishes indicate tributary habitats provide several key functions within a fish community including spawning, rearing, foraging and refuge. K E Y W O R D SCatostomus latipinnis, confluence, edge effects, movement behaviour, PIT tag, Xyrauchen texanus | INTRODUCTIONQuantifying movements of freshwater fish has been difficult due to logistical challenges of tagging and recapturing highly mobile individuals (Albanese, Angermeier, & Dorai-Raj, 2004;Gowan & Fausch, 1996;Rodriguez, 2002). Accordingly, conceptual frameworks such as the restricted movement paradigm (Gerking, 1959), long distance dispersal (Rodriguez, 2010) and confluence exchange hypothesis (Thornbrugh & Gido, 2010) that predict patterns of movement in riverine systems need testing with empirical studies. Despite the challenges studying riverine movement, advances in tagging methods now allow for freshwater fish populations within diverse communities to be studied at greater spatial and more continuous temporal scales (Cooke et al., 2013;Gowan, Young, Fausch, & Riley, 1994;Young, 2011).Sampling continuously allows increased detectability of diverse movement behaviours within and among species compared to discrete sampling events (Fausch, Torgerson, Baxter, & Li, 2002;Schlosser & Angermeier, 1995;Wiens, 2002). Intensive temporal sampling can be optimised by selecting detection sites that maximise our ability to capture the diverse inter-and intraspecific movement behaviours across time. types (Bottcher, Walsworth, Thiede, Budy, & Speas, 2013;Kiffney, Green, H...

A Tribute to Tributaries: Endangered Fish Distributions within Critical Habitat of the San Juan River, USA

“…Movement distances of Colorado Pikeminnows were best explained by season (e.g., downstream in nonsummer) and to some extent size, similar to other findings that indicate greater movement in main‐stem and tributary habitats during nonsummer periods by subadult individuals (Durst and Franssen ; Cathcart et al. ). Since our analyses relied on rare fish being both detected and captured, our small sample sizes (e.g., low number of McElmo Creek samples for Colorado Pikeminnows) may prevent higher confidence in results compared with a study with a larger sample size over a broader spatial scale.…”

“…Razorback Suckers provide a different example whereby—despite homogenous demographics—the absence of mixing among tributary groups, maturity of individuals, and limited seasonal ranges potentially indicate these tributary mouths are within home ranges that include off‐channel refugia (Cathcart et al. ), main‐stem spawning habitat (Farrington et al. ), and feeding arenas peripheral to the main stem (Tyus and Karp ).…”

“…This array involved five antennas fastened to the streambed that spanned the width of the stream in two rows (Cathcart et al. ).…”

“…), and provide refugia or foraging outside of main‐stem environments (Cathcart et al. ). While tributary systems are recognized as crucial habitats for native desert fishes (Fraser et al.…”

Flannelmouth Sucker: The Ironhorse of the Colorado River Basin

“…In McElmo Creek, these February and March migrations of thousands of individuals occur when temperatures exceed 5°C and can cover in excess of 35 km (Cathcart et al 2015(Cathcart et al , 2018. In McElmo Creek, these February and March migrations of thousands of individuals occur when temperatures exceed 5°C and can cover in excess of 35 km (Cathcart et al 2015(Cathcart et al , 2018.…”