Short communication Length–weight relationships of fish species caught in the Upper Uruguay River, Brazil By A. P. de Oliveira Nun˜er and E. Zaniboni-Filho Laborato ´rio de Biologia e Cultivo de Peixes de A ´ gua Doce, Universidade Federal de Santa Catarina, Rodovia, Floriano ´polis, Santa Catarina, Brazil Summary Length–weight relationships were estimated for 56 species, representing seven orders and 17 families of fishes from the Upper Uruguay River, Brazil. For most of these species, no length–weight relationships were previously available. Introduction The Uruguay River in South American originates in Brazil and together with the Parana´ and Paraguay rivers forms the Prata Basin, which has a drainage area of 3.1 million km 2 . Data for this survey aimed to evaluate the influence of damming on fish populations in the Upper Uruguay River. From these data, length–weight relationships were reported for 56 fish species, with other information available in Zaniboni- Filho et al. (2004). Materials and methods Fishes were sampled at 2- or 3-month intervals from Septem- ber 1995 to March 2002, at 15 sites distributed along the Upper Uruguay River basin. Gillnets with different mesh sizes, seine nets, hook and line and cast net were used, but a standard fishing effort was always made at each site. The equipment was selected according to the environmental and hydrological conditions of the sampling sites. Nets were retrieved after 12 h. The captured specimens were identified in the field, measured to the nearest milli- meter total length using an ictiometer, and to the nearest 0.01 g of fresh weight with an electronic balance. When necessary, fish samples were sent to senior taxonomists for identification. Length–weight relationships were estimated using the model: log W= log a+blog L, where W is the fresh weight in grams, L is the total length in cm and a and b the equation parameters. The model was estimated for each species using the linear function of the GRAPHPAD PRISM GRAPHPAD PRISM 4.0 software. Results and discussion Analyzed were 24 865 fishes total, distributed among 56 species representing seven orders and 17 families from the Upper Uruguay River, Brazil (Table 1). Table 1 Total length (L, cm) and weight (W, g) relationships for fish species caught in Upper Uruguay River, Brazil, September 1995–March 2002 Order Family Species n Lmin–Lmax b CI for b a CI for a R 2 Atheriniformes Atherinidae Odontesthes bonariensis 10 6.9–20.7 3.12 3.00–3.25 0.003 0.002–0.005 0.99 Characiformes Acestrorhynchidae Acestrorhynchus pantaneiro 1538 6.0–34.3 3.23 3.21–3.26 0.004 0.0040–0.0044 0.97 Anostomidae Leporinus amae a 398 8.5–19.4 2.98 2.86–3.10 0.001** 0.0007–0.0023** 0.86 Leporinus obtusidens a,b 92 20.0–76.0 2.14 1.95–2.33 0.406 0.206–0.800 0.85 Leporinus striatus b 20 11.3–16.4 2.95 2.59–3.32 0.010 0.004–0.025 0.94 Schizodon nasutus a 1058 11.0–43.5 2.98 2.95–3.01 0.010 0.009–0.011 0.97 Characidae Astyanax bimaculatus a 1776 2.4–17.5 3.23 3.19–3.26 0.009 0.008–0.010 0.95 Astyanax fasciatus a 2388 1.5–16.8 3.25 3.22–3.27 0.006 0.006–0.007 0.97 Astyanax gr. scabripinnis a 2676 1.7–15.6 3.22 3.20–3.24 0.007 0.006–0.007 0.97 Bryconamericus iheringii 1409 1.5–11.4 3.30 3.25–3.33 0.006 0.005–0.006 0.95 Bryconamericus stramineus 793 1.9–11.4 3.27 3.17–3.35 0.006 0.005–0.006 0.88 Galeocharax humeralis 284 10.5–30.5 3.29 3.21–3.37 0.004 0.003–0.005 0.96 Oligosarcus brevioris 188 4.0–28.0 3.12 3.06–3.18 0.007 0.006–0.008 0.98 Oligosarcus jenynsii 1127 2.0–31.0 3.04 3.02–3.07 0.008 0.008–0.009 0.98 Salminus brasiliensis 194 47.0–91.0 2.77 2.56–2.96 0.032 0.014–0.075 0.79 Serrasalmus spilopleura 198 6.0–26.0 3.29 3.25–3.32 0.010 0.009–0.011 0.99 Curimatidae Steindachnerina biornata 306 3.0–18.8 3.03 2.99–3.08 0.013 0.011–0.014 0.98 Steindachnerina brevipinna 557 3.7–22.6 3.06 3.00–3.11 0.011 0.010–0.013 0.96 Erythrynidae Hoplias lacerdae b 439 3.8–74.5 2.98 2.93–3.04 0.011 0.009–0.013 0.96 Hoplias malabaricus 290 13.1–55.2 3.08 3.02–3.13 0.008 0.007–0.010 0.98 Parodontidae Apareiodon affinis 848 3.2–18.1 3.22 3.18–3.25 0.006 0.005–0.006 0.98 Prochilodontidae Prochilodus lineatus 171 16.6–80.0 3.06 2.90–3.22 0.011 0.006–0.021 0.89 J. Appl. Ichthyol. 25 (2009), 362–364 Ó 2009 The Authors Journal compilation Ó 2009 Blackwell Verlag, Berlin ISSN 0175–8659 Received: June 21, 2008 Accepted: September 29, 2008 doi: 10.1111/j.1439-0426.2009.01233.x U.S. Copyright Clearance Centre Code Statement: 0175–8659/2009/2503–0362$15.00/0