Electrofishing method improves evaluation of amphibian larvae abundance: a case of “beaver rivers”

Abstract

There are many locations in Russia where Eurasian beaver (Castor fiber) populations have been restored. As a keystone species, beavers provide wide-ranging direct and indirect impacts on aquatic ecosystems. In particular, beaver-created ponds are sites for spawning and nursery places for tadpoles of the brown frogs (genus Rana). Because of such impacts, study techniques for assessing aquatic organism abundance are being developed. We compared two methods for estimating tadpole abundance: traditional catches by dipnet and electrofishing. Our results show that the dipnet catch data for the shallower ponds with larger water surface area were five times lower than that obtained by electrofishing. Therefore, we conclude that dipnet catches are not suitable for comparing the relative abundance of tadpoles in the two beaver ponds that were studied.

Signals of decline of flagship species Ambystoma altamirani Dugès, 1895 (Caudata, Ambystomatidae) in a Mexican natural protected area

“…A trap was set in a preselected pool in a stream for 16-24 hours and then checked for A. altamirani. When transects were implemented, a 150-200 m stretch of stream was sampled visually, with hand dip nets or using a backpack electrofisher (ETS Electrofishing Systems) with reduced voltage (Brown and May 2007;Dgebuadze and Bashinskiy 2016). During visual samples, two surveyors walked along the stream banks searching for A. altamirani, taking note of the presence of fish.…”