Biological Aspects on the Blue Crab, Callinectes sapidus (Rathbun, 1896) Inhabiting the Bardawil Lagoon, Northern Sinai, Egypt

Abstract

C. sapidus originated from the western Atlantic, but now became common and occurs in the entire Mediterranean where it is considered an invasive species (Streftaris & Zenetos, 2006). After its first record in the Venice lagoon at northern Adriatic by Giordani Soika (1951), it has been widely reported from various different Mediterranean regions, especially in the eastern part (Galil et al., 2002). Several records have been published in recent years, with regard to the species' distribution in the Adriatic (Florio et al., 2008) and other parts of the Mediterranean Sea (Tuncer & Bilgin, 2008), relating this expansion to the increase of maritime transportation. The importance of the commercial and recreational fishing of this species is increasing, while its occurrence and ecological significance are receiving more interest along the Mediterranean coast of Egypt (Miller et al., 2011). Bardawil Lagoon is one of the five northern lakes in Egypt. It is bordered from the north by a convex sand barrier that separates it from the Sinai Mediterranean coast and from the south by the sand dune belt. The extreme eastern part of this lagoon is a Zaranik Protectorate (Khalil et al., 2013). Although it is shallow and oligotrophic, it represents one of the most important lagoons in Egypt as a source of good quality fish as well as a good habitat for wildlife (Touliabah et al., 2002). It is the least polluted lagoon in Egypt and in the entire Mediterranean region which makes it the main ecological and economic natural resource of the North Sinai region (Khalil et al., 2013). Callinectes spp. has been studied by several scientists all over the world. These studies provided a good understanding of the biology of this genus such as population dynamics in a sub-estuary of the central Chesapeake Bay, U.S.A (Hines et al., 1987 and Sharov et al., 2003) and in the Gulf of Nicoya, Costa Rica (Fischer & Wolff, 2006). Blue crabs are known as iteroparous, which mean they are characterized by multiple reproductive cycles over the course of their lifetime (Jivoff et al., 2007). This allows them to release eggs over an extended period to take advantage of favorable environmental conditions that may exist for only part of their spawning season. However, detailed information on the biology of C. sapidus in Bardawil Lagoon is scarce. These studies are needed in order to document the intraspecific variations between populations from the different sites, as well as for the proper exploitation and management of the fishery of this economically important species. This paper aims to represent a comprehensive study in the biology of C. sapidus from Bardawil Lagoon comprising its abundance, frequency distribution and reproductive biology. MATERIALS AND METHODS Study Area: Bardawil Lagoon is a natural lagoon located on the northern coast of the Sinai Peninsula, Egypt (Fig. 1). It is one of the least polluted lagoons in Egypt's Northern Lakes (Fanos et al., 1994) as well as in the entire Mediterranean Sea. The Egyptian authorities allow only very limited ec...