Challenges for Diadromous Fishes in a Dynamic Global Environment

Status of Diadromous Fish Species in the Restored East Hammar Marsh in Southern Iraq

Abdul-Razak M. Mohamed, Najah A. Hussain, Sajed S. Al-Noor, Brian Coad, and Falah M. Mutlak


Abstract.—A total of 31 fish species belonging to 14 families were collected from the restored East Hammar marsh from October 2005 to September 2006 using seine net, electrofishing gear, fixed gill net, and dip net. Eleven marine diadromous species were caught, representing 35.5% of the total number of species, which is similar to the fish assemblage of the Shatt Al-Arab River during the 1970s and 1980s. Marine diadromous species in the East Hammar marsh were divided into a resident group, including only one species (greenback mullet Liza subviridis), a seasonal group represented by three species (hilsa Tenualosa ilisha, moustached thryssa Thryssa mystax, and dusky frillgoby Bathygobius fuscus), and an occasional group consisting of seven species (yellowfin seabream Acanthopagrus latus, spotted scat Scatophagus argus, sobaity seabream Sparidentex hasta, Klunzinger’s mullet L. klunzingeri, mud skipper Boleophthalmus dussumieri, long billed half beak Rhynchorhamphus georgii, and ocellated sole Brachirus orientalis). These species were all derived from the Arabian Gulf. Marine fish comprised 15.8% of the total catch of which hilsa was the most abundant comprising 10.1%, followed by moustached thryssa (3.8%) and greenback mullet (1.6%), of the total catch. Water temperature showed positive correlations with both number and total catch of marine species. The marine assemblage in the East Hammar marsh consisted of small-sized (juvenile) individuals. Hilsa fed mostly on alga and diatoms; greenback mullet on diatoms, higher plants, and organic materials; Klunzinger’s mullet on diatoms and organic materials; moustached thryssa on insects, shrimps, and fish; desky frillgoby on shrimps and fish; and yellowfin seabream on shrimps and insects. The presence of marine fish species has major effects on the seasonality and levels of ecological indices (richness, diversity, and evenness) of the fish assemblages in the East Hammar marsh. The restored East Hammar marsh has regained its original biological role as a nursery as well as a forage ground for marine diadromous fishes.