Fish assemblage of restored Al-Hawizeh marsh, Southern Iraq

Al-Hawizeh marsh is one of the largest wetlands in south Iraq. During last two decades, 65% of a permanent marsh was drained and it led to a substantial loss of native aquatic flora and fauna. The marsh was reflooded in April 2003. The characteristics of fish assemblage in this marsh were described after three years of the restoration. A total of 4715 fishes of 15 species were caught since October 2005 to September 2006, using different fishing gears. The fish species in the marsh were divided into resident, seasonal and occasional groups. Liza abu was the most abundant species comprising 37.1% of the total numbers followed by Barbus luteus (29.4%), Carassius auratus (15.3%), Alburnus mossulensis (4.88%) and Aspius vorax (4.14%). Fish species diversity index ranged from 0.88 to 2.1, richness from 0.73 to 2.42 and evenness from 0.49 to 0.85. The diet varied among the fish species, most of them depended on two or three major food items. Several cyprinid species disappeared from the restored marshes or decreased in their abundance. This could be related to reduced water supply and effectively eliminated the spring flood pulses that sustained wetland ecosystems in the lower Tigris-Euphrates basin. Increase of salinity, scarcity of benthic food resources and competition with alien/introduced species have also detrimental effects on native cyprinid fishes.