Electroshocking as a survey technique for stream‐dwelling amphibians

Abstract

Electroshocking has long been employed as a survey technique for fish, but has not been directly tested against rock rolling as a survey methodology for stream-dwelling amphibians. Electroshocking has the potential to reduce habitat disturbances that result from surveys, improve abundance estimates, and reduce injuries and effort in collecting data. Furthermore, accurately quantifying species and survey techniquespecific estimates of detection probabilities is critical for appropriately interpreting survey results and employing occupancy analyses. We tested the efficiency and sensitivity of rock rolling and electroshocking in detecting Idaho giant salamanders (Dicamptodon aterrimus) in a small stream in northern Idaho, USA, by sampling short (25 m) segments of a stream using both survey techniques. We also conducted multi-pass surveys of 400-m stream segments to estimate detection probabilities for D. aterrimus and Rocky Mountain tailed frog (Ascaphus montanus). Using electroshocking, we detected D. aterrimus 40% more often than by rock rolling and detected 3.5 times as many individuals, with substantially reduced effort. Using electroshocking, detection probabilities were 1.0 for D. aterrimus and 0.79 (95% CI ¼ 0.63-0.88) for A. montanus. Our results show electroshocking to be a much more sensitive and efficient method of detecting streamdwelling amphibians than the traditional technique of rock rolling. Electroshocking can serve as an important survey technique for secretive stream-dwelling amphibians, allowing managers to quickly and safely acquire valuable data of better quality. ß 2012 The Wildlife Society.

Using environmental DNA methods to improve detectability in a hellbender (Cryptobranchus alleganiensis) monitoring program

“…Our surveys also typically took place upstream of eDNA sampling sites and surveys generally continued for up to 250-300 m. Thus, the characteristics of a lotic system alone likely do not explain our lack of pattern. Instead, the significant relationship observed by Pilliod et al (2013) is probably more related to the ability to more completely census stream amphibian populations, as well as a greater number of individuals, in the Idaho stream system (Cossel et al, 2012). Third, the samples for this portion of the study were collected from June to August, which is confounded by potential temporal variation, and this is supported by the fact that the three highest eDNA values were collected in August, close to the breeding season (Table A1).…”

Casting a broader net: Using microfluidic metagenomics to capture aquatic biodiversity data from diverse taxonomic targets

“…Backpack electrofishing (Cossel et al, ) for fish, amphibians, and crayfish was conducted at sites below (sites 1, 2) and above (sites 4, 5) the OHRC within a 15‐day period (July 20, 2017 to August 04, 2017). Site 3 (hatchery outflow) was not evaluated by electrofishing.…”

An analytical framework for estimating aquatic species density from environmental DNA

“…() study that were sampled with electrofishing, not those that were only sampled with the kick‐net technique (see Pilliod et al., ) because this latter method did not provide reliable metrics of salamander densities. On the other hand, electrofishing has been shown to be one of the most reliable field sampling methods for larval and paedomorphic life stages of this species (Cossel, Gaige, & Sauder, ; Pilliod et al., ). The environmental characteristics (see Table ) of the five sites we used were not significantly different than those of the other sites in terms of stream flow (sites used: = 1.0 m 3 /s; other sites: = 0.9 m 3 /s), temperature (sites used: = 11.5°C; other sites: = 9.7°C), and depth (sites used: = 25.2 cm; other sites: = 21.4 cm).…”

“…Here, we used the sites from the Pilliod et al (2013) study that were sampled with electrofishing, not those that were only sampled with the kick-net technique (see Pilliod et al, 2013) because this latter method did not provide reliable metrics of salamander densities. On the other hand, electrofishing has been shown to be one of the most reliable field sampling methods for larval and paedomorphic life stages of this species (Cossel, Gaige, & Sauder, 2012;Pilliod et al, 2013). The environmental characteristics (see Table S1) of the five sites we used…”