摘要
Objective:To describe the growth,reproductive biology and abundance of the population of invasive shrimps Palaemon elegans(P.elegans)in one of the branches of Garmat Ali river at Basrah,Southern Iraq.Methods:Monthly samples of the prawn P.elegans were collected with a bottom hand net(40 cm,0.5 mm mesh)hauled over a distance of 10 m.A simple random sampling was conducted monthly between December 2012 and November 2013.Results:Seasonal changes were observed in the composition of the population of the species during the study year with the highest abundance in 2013 and the lowest abundance for the males was reported in January and for the females occurred in June.Salinity showed a significant correlation with the abundance of shrimps at the sampling site.The largest female measured 67.90 mm while the corresponding value for males was 61.31 mm.The proportion of ovigerous adults rose during spring season to peak on about July and ovigerous prawns were taken in all months of the year.The sex ratio indicated a preponderance of females over males in all months in the study period.Each females produced around 36-1324 eggs and the incubation period lasted for 11-14 days at 17-29°C.Conclusions:The results of the present study indicate that this species has a wide distribution range,high density,and great reproduction potential.This study reveals the lack of researches on this species in environments of Shatt Al-Arab river and its branches.Thus,P.elegans has most likely formed a permanent population in all the brackish waters in Basrah area.
