Ecology, Environment and Conservation Paper

FISH FAUNA FROM THE IRRICATION SYSTEM OF THE LOWER VALLEY F THE COIORAGIO RIVER, ARGENTINA

A.C. Lopez Cazoria, and N.S. Sidorkewicr

Abstract

The area targeted for this study is an irrigation scheme known as LowerValley of the Colorado River (390 10'- 390 55' 5;62° 55'- 63° 05'W), where approximately 92,000 ha. are under irrigation.The aim of this study was to ascertain fish species composition, to obtain biological information based on fish length, weight, and to analyse indices of species diversity. Fish of eight taxa were captured: Cyprinus cerpio, Oligosarcus jenynsia Astyanax eigenmanniorum, Odontesthes bonariensis, Mugil lizaienynsia multidentata, Percichthys trucha and Hatcheria macroei.The results showed a similar diversity in irrigation (1.81 bits) and drainage (2.02 bits) channels.A high correlation in fish composition between both type of channels was found (r =0.87; p < 0.01), independently of the differences between both aquatic environments. One noticeable feature is that C. carpio, an exotic species, appeared as a dominant fish, representing the 42% and 53% of the total catch in irrigation and drainage networks, respectively.