J Appl Ichthyol. 2017;1–3. wileyonlinelibrary.com/journal/jai | 1 © 2017 Blackwell Verlag GmbH Received: 20 February 2017 | Accepted: 4 July 2017 DOI: 10.1111/jai.13443 TECHNICAL CONTRIBUTION Length–weight relationships of fishes from the estuary of the Macaé River, Southeastern Brazil P. A. Catelani 1,2 | A. B. Bauer 1,2 | A. C. Petry 2 1 Universidade Federal do Rio de Janeiro, Campus UFRJ - Macaé Professor Aloísio Teixeira, Programa de Pós-Graduação em Ciências Ambientais e Conservação, Macaé, RJ, Brazil 2 Universidade Federal do Rio de Janeiro, Núcleo em Ecologia e Desenvolvimento Socioambiental de Macaé (NUPEM/UFRJ), Macaé, RJ, Brazil Correspondence Paula Araujo Catelani, Universidade Federal do Rio de Janeiro, campus UFRJ - Macaé Professor Aloísio Teixeira, Programa de Pós-Graduação em Ciências Ambientais e Conservação, Macaé, RJ, Brazil. Email: ktelani@gmail.com Summary The present study provides the length-weight relationship (LWR) for eight species from the estuarine stretch of the Macaé River, Rio de Janeiro State, Brazil. Data were obtained quarterly between June 2011 and March 2012. These LWRs are the first records for six species and present new maximum values of total length for three ones. 1 | INTRODUCTION Population-based descriptors can be viewed as heuristic tools, since they provide information about the species biology, allowing compari- sons in the scales of space and time (e.g., Brito, Maia-Barbosa, & Pinto- Coelho, 2013; Pazianoto, de Cionek, Fogaça, & Benedito, 2016). In this sense, the length-weight relationship (LWR) adds essential data for the evaluation of fishery resources, estimates of biomass from data based on visual census, as well as the condition factor or well-being of species of particular interest (Vazzoler, 1996; Vianna, Costa, & Ferreira, 2004). LWR data are available for most European and North American fish, but they are still lacking for most South American species (Giarrizzo et al., 2006; Joyeux, Giarrizzo, Macieira, Spach, & Vaske, 2008). In southeastern Brazil, the Fluminense Ecoregion is characterized by high rate of endemism (42% of the 111 freshwater fish species recorded) in a relatively small geographic range (14,053 km 2 ) (Abell et al., 2008; Albert, Petry, & Reis, 2011). Among those drainages, the Macaé River is the longest one, with 130 km. The species richness on the estuarine stretch of the Macaé River surpass one hundred species, mostly comprised of eurihaline species (Catelani, Petry, Di Dario, dos Santos, & Mincarone, 2014). By presenting the LWRs of eight species from the estuary of the Macaé River, this study adds information to other recent efforts engaged to the ichthyofauna of the Fluminense Ecoregion (Franco, Araújo, & Araujo, 2014; Gasparini, Gomes, & Macieira, 2016). 2 | MATERIALS AND METHODS The Macaé River originates in the Atlantic forest hills of the Rio de Janeiro State, Brazil (22° 21’– 22° 28’ S, 42° 27’– 42° 35’ W) and dis- charges as a seventh order channel into the Atlantic Ocean, near the municipality of Macaé. The data were obtained from quarterly surveys conducted along 16 km of the estuary of the Macaé River at five sampling stations, between June 2011 and March 2012 (more details in Catelani et al., 2014). Fishes captured with the use of gillnets (mesh sizes 15 to 45 mm), cast nets (mesh sizes 10, 20 and 25 mm), and beach seine nets (mesh size 5 mm) were fixed in a 10% solution of formalin and later preserved in 70% alcohol. All specimens were identified at the species level, and biometric data, including total length (TL, cm) and total wet weight (TW, g) were recorded. The species were assigned according to their zoogeographic origin in freshwater (primary and secondary divisions) and marine (peripheral or marine division), according the classification of families proposed by Nichols (1928) and Myers (1938). Vouchers were deposited in the Fish Collection of the Núcleo em Ecologia e Desenvolvimento Socioambiental de Macaé, Universidade Federal do Rio de Janeiro (NPM). The parameters of the growth model TW = aTL b were estimated by linear regressions using log transformed data: lnTW = ln a + blnTL, where TW and TL are total wet weight and length, respectively, a is the intercept, and b is the allometric coefficient. The absences of