Stocking of Rainbow TroutOncorhynchus mykiss commonly provides seasonal or mitigation fisheries; however, these fish are usually small and ecosystem effects are spatially or temporally limited. Yet agencies receive requests to stock Rainbow Trout in relatively natural settings (i.e., not tailwater or mitigation fisheries), where introductions may have greater ecosystem consequences. The size of introduced fish is an important factor in determining biotic interactions with native species; therefore, our objectives were to assess the seasonal feeding ecology and microhabitat use of large ( 265-530 mm TL) nonnative Emmerson strain Rainbow Trout in a relatively unaltered, groundwater-influenced, warmwater stream of the Ozark Highlands. Rainbow Trout consumed a variety of prey; however, diets differed between cool (winter and spring) and warm (summer) seasons. Cool-season Rainbow Trout exhibited a mixed feeding strategy, with individual specialization on crayfishes and fishes and generalist feeding on Ephemeroptera and Diptera, but Gastropoda were the dominant prey. Feeding strategy in the warm season switched to individual specialization on numerous prey types. Overall, larger prey resources were important components of Rainbow Trout diets. Piscivory was relatively high in both seasons, and crayfishes were one of the most important prey types across seasons. Selection of coarse substrates and deeper-water microhabitats (>0.95 m) was similar between seasons. Rainbow Trout selected the lowest-velocity microhabitats available during the warm season and moderate velocities in the cool season. Rainbow Trout were five times more likely to be associated with cover in the warm season. Due to their higher temperature tolerance, Emmerson strain Rainbow Trout may persist in Ozark Highland streams, where they disrupt local food webs and occupy habitat otherwise selected by native fish, such as Neosho Smallmouth Bass Micropterus dolomieu velox. If native species conservation is a priority for agencies, then caution regarding Rainbow Trout stockings may be warranted.

Stocking Rainbow Trout Oncorhynchus mykiss to create additional angling opportunities is common; however, the spatial and temporal dynamics of such stocking practices are unclear in groundwater‐influenced, warmwater streams. Our objectives were to determine Rainbow Trout dispersal from a stocking location on Spavinaw Creek, Oklahoma and to quantify apparent survival of two cohorts of Rainbow Trout stocked in November 2018 and February 2019. Rainbow Trout were PIT‐tagged prior to autumn (N = 495) and winter (N = 605) stocking and located poststocking using both an active floating array and two passive fixed arrays. We actively tracked a 6‐km extent every 2–3 weeks poststocking and found that PIT‐tagged Rainbow Trout dispersal ranged from 0 to 4 km with ~90% of detected tagged fish remaining within 1 km of the stocking location. Directional movement by stocked Rainbow Trout was evident with upstream movements related to increases in daily water discharge and downstream movements related to decreases in daily discharge. Estimated apparent weekly survival of Rainbow Trout was lowest during the first 2 weeks poststocking (91% and 75% for autumn and spring cohorts, respectively). Apparent weekly survival rates for both autumn and spring stocked fish increased through winter and spring when maximum water temperatures were below 25℃, reaching survival rates of 99% by the end of spring. Rainbow Trout persisted in Spavinaw Creek throughout the summer; however, the weekly apparent survival rate declined for both cohorts (93%) when maximum daily water temperatures exceeded 25°C. Our results can be used to guide stocking decisions in similar warmwater streams and suggest that Rainbow Trout persist through spring and summer poststocking under the conditions encountered during our study.

Advantages of PIT tags are their small size, longevity, and low cost compared to other tags. They are often used in fisheries to study movement patterns and survival or to estimate population size. However, PIT tags are limited by their short detection distance. Mobile PIT antennas may increase the utility of PIT tags in fisheries. In this study, we synthesized current detection efficiency literature for mobile PIT antennas, determined physical factors that decreased PIT tag detection probabilities for our antenna, determined factors that influenced the proportion of PIT‐tagged suckers detected by our mobile antenna, and summarized techniques used to increase detections of PIT‐tagged suckers using mobile antennas in a wadable stream. Our literature review indicated that tag size and orientation were the most important factors affecting detection probabilities. However, our manual testing suggested that the detection probability for our antenna was primarily influenced by water depth of the tag and distance from the antenna. Our sucker detection data showed that detection efficiency in our stream was most influenced by discharge, turbidity, and sample date. Tracking methods that include targeting key habitats (e.g., rootwads) and using natural features to congregate tagged fishes (e.g., riffles or pinch points) may increase detection efficiency in wadable streams. This is the first formal review of factors affecting mobile PIT antenna detection efficiency. The published literature, combined with our study results, indicates that several factors need to be considered prior to mobile PIT antenna tracking.

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