Published online by Cambridge University Press: 30 November 2012
This is the first record of a ladyfish (Elops smithi) larva in Uruguay and the southernmost South Atlantic record. We provide morphological–merisitc and environmental information about the larva collected in March 2010 in brackish waters of the Solís Grande estuary. The sampling site was 0.9 m depth, water was warm (21.7 °C), low salinity (12.3) and with high oxygen content (7.7 mg l−1). The larva was very transparent, 31 mm in standard length and had a total of 76 myomeres. The dorsal fin (24 rays) and the anal fin (16 rays) did not overlap. The caudal fin was forked; the pectoral fin without rays and pelvic fin was in an early phase. The swim bladder was inverted U shaped. The half premaxilla had 8 teeth and the half mandible 10 (of similar size and appearance). Pigments were present in the ventral line (from the thorax to anus) and in the middle lateral trunk and caudal peduncle line. These characteristics suggested an early-metamorphic stage of the larva. This species is recorded with low abundances in southern Brazil. The collection of this individual occurred during a period of strong El Niño (2009–2010). These events are associated with warm sea surface temperature anomalies in the south-western Atlantic and northerly winds anomalies in the Brazilian–Uruguayan continental shelf.