Monitoring fish communities in wadeable lowland streams: comparing the efficiency of electrofishing methods at contrasting fish assemblages Franco Teixeira-de Mello & Esben A. Kristensen & Mariana Meerhoff & Iván González-Bergonzoni & Annette Baattrup-Pedersen & Carlos Iglesias & Peter B. Kristensen & Néstor Mazzeo & Erik Jeppesen Received: 17 February 2013 / Accepted: 30 September 2013 / Published online: 5 November 2013 # Springer Science+Business Media Dordrecht 2013 Abstract Electrofishing is considered a reliable tool to assess the assemblages and biodiversity of fish in wadeable streams. The most widely used electrofishing techniques (point [P], single-pass [S-P], and multiple- pass [M-P]) vary as to the effort needed for sample collection, and this may potentially influence the de- gree of accuracy. Moreover, little is known about the comparability of the methods and their specific perfor- mance in streams with different fish assemblages. The aim of this investigation was to validate (using M-P sampling as reference) the use of P and S-P electrofish- ing techniques to accurately assess the richness, density and size distribution of fishes in small streams at both regional and global scale independently of fish assem- blages and geographical region. We sampled 50-m-long reaches in a total of 33 lowland stream reaches that were located in different climatic and biogeographical regions (Uruguay and Denmark) and hosted different fish assem- blages. Subtropical fish communities exhibited higher richness (Uy: 12–32, Dk: 1–9) and densities (Uy: 1.3– 5.2, DK: 0.1–4.9 in. m -2 ) than temperate streams. We applied both "global models" using the entire database (33 sites) and "local models" including the same number of sites but using the climatic region as a model variable. Regression analyses revealed that the P, S-P and M-P methods all provided an adequate picture of the species composition and size distribution, and transfer equations for comparison between methods are thus not required. Conversely, richness was better predicted by S-P and by P techniques for regional and global models, respectively. Transfer equations obtained for abundance revealed that the P and S-P models can accurately transform catch data Environ Monit Assess (2014) 186:1665–1677 DOI 10.1007/s10661-013-3484-9 F. Teixeira-de Mello : M. Meerhoff : I. González-Bergonzoni : C. Iglesias : N. Mazzeo Departamento de Ecología & Evolución, CURE-Facultad de Ciencias, Universidad de la República, Tacuarembó s/n, Maldonado CP 20000, Uruguay F. Teixeira-de Mello : M. Meerhoff : I. González-Bergonzoni : C. Iglesias Asociación Civil Investigación y Desarrollo I+D, Iguá 4225, CP 11400 Montevideo, Uruguay E. A. Kristensen : M. Meerhoff : I. González-Bergonzoni : A. Baattrup-Pedersen : P. B. Kristensen : E. Jeppesen Department of Bioscience, Aarhus University, Vejlsøvej 25, 8600 Silkeborg, Denmark I. González-Bergonzoni : E. Jeppesen Sino-Danish Centre for Education and Research (SDC), Beijing, China E. Jeppesen Greenland Climate Research Centre (GCRC), Greenland Institute of Natural Resources, Kivioq 2, P.O. Box 570 3900, Nuuk, Greenland F. Teixeira-de Mello (*) Ecología y Rehabilitación de Sistemas Acuáticos, CURE-Facultad de Ciencias, Universidad de la República, Tacuarembó s/n, Maldonado CP 20000, Uruguay e-mail: frantei@fcien.edu.uy