Although numerous studies have assessed retention and survival of passive integrated transponder (PIT) tags, data are scattered and information gaps remain for many diminutive fishes. Our study objectives were to 1) systematically review PIT tag studies and summarize retention, growth, and survival data for warmwater fishes; and 2) conduct a laboratory study to evaluate the retention, survival, and growth effects of intracoelomic-placed, half duplex PIT tags on six small-bodied species common to warmwater streams. Our systematic review suggested small sample sizes were common within PIT tag retention and survival studies (39% with n 20) and that many experiments (15%, 14 of 97) failed to use control fish as part of their evaluations. Studies focused primarily on short-term changes (15 d to 2 y) in tag retention and survival. Tag retention was equal to or greater than 90% in 85% of the experiments reviewed and median survival was 92%. Growth was reported by fishes in the majority of reviewed studies. We found similar results after PIT tagging (peritoneum tagging using 12-or 23-mm half duplex tags) adult Cardinal Shiner Luxilus cardinalis, Central Stoneroller Campostoma annomalum, Greenside Darter Etheostoma blennioides, Orangethroat Darter Etheostoma spectabile, Slender Madtom Noturus exilis, and juvenile Smallmouth Bass Micropterus dolomieu. Tag retention for all species was high, with only one tag loss recorded after 60 d. Survival was also high (!88%) for all of our species with the exception of Orangethroat Darter (56% survival). No significant difference in mean growth between treatment and control groups was found. Both our results and the findings of the literature review suggested generally high tag retention and low mortality in tagged fishes (across 31 species reviewed). However, within our study (e.g., Orangethroat Darter) and from the literature, examples of negative effects of PIT tagging on fishes were apparent, suggesting methodological testing is prudent before using PIT tags in field studies. We suggest future studies would benefit from addressing the behavioral implications that may be associated with tagging and examination of longer-term tag retention. Furthermore, standard reporting (i.e., sample sizes) in PIT tag studies would be beneficial, and use of control subjects or groups for statistical comparisons is needed.Citation: Musselman WC, Worthington TA, Mouser J, Williams DM, Brewer SK. 2017. Passive integrated transponder tags: Review of studies on warmwater fishes with notes on additional species.

Temporal and spatial variability in streams result in heterogeneous gear capture probability (i.e., the proportion of available individuals identified) that confounds interpretation of data used to monitor fish abundance. We modeled tow-barge electrofishing capture probability at multiple spatial scales for nine Ozark Highland stream fishes. In addition to fish size, we identified seven reach-scale environmental characteristics associated with variable capture probability: stream discharge, water depth, conductivity, water clarity, emergent vegetation, wetted width–depth ratio, and proportion of riffle habitat. The magnitude of the relationship between capture probability and both discharge and depth varied among stream fishes. We also identified lithological characteristics among stream segments as a coarse-scale source of variable capture probability. The resulting capture probability model can be used to adjust catch data and derive reach-scale absolute abundance estimates across a wide range of sampling conditions with similar effort as used in more traditional fisheries surveys (i.e., catch per unit effort). Adjusting catch data based on variable capture probability improves the comparability of data sets, thus promoting both well-informed conservation and management decisions and advances in stream-fish ecology.

Aim: Crayfish are globally diverse and one of the most important taxa in North American streams. Despite their importance, many species are of conservation concern and efforts to improve conditions are limited. Here, we address two major impediments to improving conditions: (a) our lack of knowledge of the interplay among natural landscape and human-induced changes; and (b) a very limited understanding of how species interactions affect overall crayfish distributions.Location: Ozark Highlands ecoregion, USA. Methods:We used both existing data and field-collected data to examine the relationships between 12 Faxonius species and physicochemical variables at multiple spatial scales. Data were analysed using a generalized linear mixed model. After fitting our environmental variables, we also considered possible relationships between species considered strong competitors and species occurrence. Results:Our results indicated that elevation, lithology, an interaction between drainage area and anthropogenic disturbance, and the presence of strong competitors were associated with Faxonius occurrences. Faxonius occurrences were associated with assemblage-structuring variables: lithology and elevation. More interestingly, we found several patterns of interactions between drainage area and disturbance.The most common pattern among several species was a decline in occurrence in larger drainages when disturbance was high; however, longpincered crayfish (Faxonius longidigitus) was more likely to occupy large drainages as disturbance increased.Additionally, the presence of species considered strong competitors resulted in lower occurrence probability for many species, including two of the species classified as competitors. Main conclusions:In addition to identifying the relationships between native species and assemblage-structuring variables, we show how the probability of species occurrences relate to interactions between disturbance and natural landscape features.Further, our results suggest competitor presence also plays a role in structuring distributions at the stream segment scale. Our findings emphasize the value of considering both competitor presence and interactions among landscape variables and disturbances in structuring crayfish assemblages. K E Y W O R D S

Subterranean habitats represent focal habitats in many conservation strategies; however, these environments are some of the most difficult to sample. New sampling methods, such as environmental DNA (eDNA), show promise to improve stygobiont detection, but sources of sampling bias are poorly understood. Therefore, we determined the factors affecting detection probability using traditional visual surveys and eDNA surveys for both cavefishes and cave crayfishes and demonstrated how detection affects survey efforts for these taxa. We sampled 40 sites (179 visual and 183 eDNA surveys) across the Ozark Highlands ecoregion. We estimated the detection probability of cave crayfishes and cavefishes using both survey methods under varying environmental conditions. The effectiveness of eDNA or visual surveys varied by environmental conditions (i.e., water volume, prevailing substrate, and water velocity) and the target taxa. When sampling in areas with average water velocity, no flow, and coarse substrate, eDNA surveys had a higher detection probability (0.49) than visual surveys (0.35) for cavefishes and visual surveys (0.67) had a higher detection probability than eDNA surveys (0.40) for cave crayfishes. Under the same sampling conditions, 5 visual surveys compared to 10 eDNA surveys would be needed to confidently detect cave crayfishes and 9 visual surveys compared to 4 eDNA surveys for cavefishes. Environmental DNA is a complementary tool to traditional visual surveys; however, the limitations we identified indicate eDNA currently cannot replace visual surveys in subterranean environments. Although sampling designs that account for imperfect sampling are particularly useful, they may not be practical; thus, increasing sampling efforts to offset known detection bias would benefit conservation strategies.