Análisis preliminares de la composición lipí­­dica de las gónadas de bagre negro, Rhamdia quelen (Siluriformes; Quoy y Gaimard, 1824), de dos poblaciones en diferentes estaciones del aí­±o

Abstract

Rhamdia quelen is a siluriform with an extensive geographical distribution. The species inhabits freshwater rivers and estuarine lagoons. The fatty acid composition of the fi sh gonadal tissues is the result of its diet. However, this may be affected by intrinsic or extrinsic factors. In this study, eight females of R. quelen were captured in two places: a freshwater river (SG) and a coastal lagoon (LR). In the river (SG), the capture was inside the reproductive period, and in the lagoon (LR), the capture was outside this period. Total lipids were determined gravimetrically and the fatty acids were separated by gas chromatography. Total lipid (SG=3.5%w.w.; LR=4.0%w.w.) do not show differences between the two populations. A total of 41 fatty acids were identifi ed, and among them the more relevant were: C16:0 (SG=22.7%; LR=21.4%), C18:1n9 (SG=11.5%; LR=11.7%), C20:4n6 (SG=11.1%; LR=12.5%) and C22:6n3 (SG=10.9%; LR=12.2%). Although the females belong to different ambients and season, no differences in the fatty acid composition were detected. However, studies with a greater number of samples are indispensable. A stability in the gonadal fatty acid profi le was recorded, independently of the fi sh habitat. Similar values were recorded for other species.