INOC -IIUM- International Conference on " Oceanography & Sustainable Marine Production: A Challenge of Managing Marine Resources under Climate Change, ICOSMaP”, Kuantan- Malaysia, 28-30 October 2013 Page 530 Population dynamics of grey mullet Mugil cephalus associated with seagrass community in Bardawil lagoon, Northern Sinai, Egypt. Sahar F. Mehanna 1 and Mohammed M. Hegazi 2 1 National Institute of Oceanography and Fisheries, Egypt 2 Suez Canal University, Faculty of Science, Marine Sci. Department, Egypt E-mail: sahar_mehanna@yahoo.com Abstract The evaluation and management of fisheries resources requires knowledge of spatial and temporal changes in the habitat-associations of fishes. However, most studies concerning habitat associations of fishes in the shallow areas have been limited to daytime sampling strategies. The striped mullet, Mugil cephalus is one of the most important and high valued species in Bardawil lagoon, Egypt. Long term commercial catch statistics show a significant decrease in the commercial landings of grey mullet in Bardawil lagoon since 1995. By learning more about this species and protecting the habitat upon which it depends, we can ensure that this important valuable fish remains abundant. Population dynamics of grey mullet Mugil cephalus associated with seagrass community were examined. Age was determined based on scale’s readings of fish collected in April 2009 to December 2011. Growth parameters, mortality rates, exploitation level as well as the distribution according to seagrass community were studied. The results suggest that differences in fish species richness and abundance are primarily related to habitat structure, the ecological importance and need for protection of such shallow habitats for their crucial role as nurseries for many fish species, as well as the mugilid fishery in Bardawil lagoon is heavily exploited and management measures must be applied to sustain and optimize its yield. Keywords: Bardawil lagoon, Mugil cephalus, seagrass, spatial variation, population dynamics, management. 1. Introduction Family Mugilidae (mullets) plays an important role in commercial fisheries and aquaculture worldwide and spend part of their life cycle in seagrass beds, mainly as a nursery area for spawning and/or juvenile development. On a world-wide scale, vegetated inshore areas in coastal regions generally support different fish species, a greater diversity and abundance of fish, and larger numbers of juveniles than nearby bare substrata (Kikuchi, 1974; Orth & Heck, 1980; Pollard, 1984; Rozas & Odum, 1988; Bell & Pollard, 1989; Conrow et al., 1990; West & King, 1996). Mullets species are considered as one of the most valuable fish resources at Bardawil lagoon where they contribute about 26.4% of the total lagoon production and about 56.5% of fish production in the lagoon (1998-2011, Fig. 1&2). Their catch is greatly fluctuated with a minimum of 703 ton during 2004 and a maximum of about 1298 ton during 2008 (GAFRD annual statistics 1998-2011). The relative abundance of the mullets in Bardawil Lagoon shows a general trend of decline in spite of the general increase in fishing effort. The mullet catch composed mainly from six species; Mugil cephalus, Liza ramada, Liza aurata, Liza saliens, Chelon labrosus and Liza carinata of which striped mullet Mugil cephalus is the most abundant species contributing more than 50% of the