Effect of lessepsian immigrant species on demersal catches operating along the Egyptian Mediterranean waters

The present study was carried out on the lessepsian immigrant fishes caught with trawl nets in the Egyptian Mediterranean waters. Based on previously reported data during summer and winter 2008 and winter spring 2009, along the western and eastern Egyptian Mediterranean waters from El-Arish to El-Salloom using the research vessel Salsabil of the National Institute of Oceanography and Fisheries. The relative abundance by number and weight of immigrant species represented 60.46% and 48.50% respectively from the total fish catch. El –Shalya region contained the most abundant species by number (94.41%) and weight (95.11%). The analysis of variance test, indicated that differences in abundance of immigrant species in different water depths by number (F = 1.225, p 0.05) and by weight (F = 1.235, p 0.05) were not significant. The most common immigrant species was Erugosquilla massavensis, representing 26.61% by number, and Fistularia commersonii dominated the immigrant species catches by weight (23.22%). Immigrant fishes expanded their distribution up to El-Salloom at the western border of the Egyptian Mediterranean coast. The results of Shannon’s Index (H ) and Simpson s dominance index (c) led us to consider that the local community at depth 100-150 was more diverse than other habitats.