Trawl Fishery

Trawling is an important fishing method used by the fishermen in the Gulf of Suez. The trawl fishery in the Gulf of Suez is known to have very low selectivity. The trawl nets of the fishery retain large numbers of juvenile individuals, which has negative effects on the marine resources.

2.2. Selectivity of fishing gears:

There are several studies dealing with the selectivity of trawl fishery around the world (Broadhurst and Kennelly, 1997, Broadhurst et al., 2004, Broadhurst et al., 1999, Grimaldo et al., 2007). In Egypt there is no studies dealing with the selectivity of trawl fishery and there are limited studies dealing with selectivity of trammels nets (Al-Sayes, 1992, 2002). The present study is the first study in Egypt that deals with

Thus, square meshes provide more opportunities for fish to escape through open meshes. There have been attempts to use square mesh codends or adding square mesh panels to diamond mesh codends in order to allow undersized fish to escape through the codend (Broadhurst and Kennelly, 1997, Broadhurst et al., 2004, Broadhurst et al., 1999, Grimaldo et al., 2007). In comparison with a diamond mesh codend with the same mesh size, a square mesh codend produced up to 50%- higher in L50 (50% retention length) and a smaller SR (selection range) for several species (Broadhurst et al., 2004, Halliday and Cooper, 2000). The current 4.0cm diamond meshes codend enforced by law in the Northwest Mediterranean demersal trawl fishery. Also 4.0cm diamond mesh codend produces catches with large amounts (one third of the total captured biomass) of discards composed of commercially important species with minimum landing size (MLS) and of noncommercial species (S´anchez et al., 2004; Mart´ın et al.,1999). The square mesh (SM40) showed a significantly higher mean selection length (L50) than the diamond mesh (DM40.) For hake the L50 was 16.0 cm in SM40 and 10.1 cm in DM40 (Bahamon et al

A square mesh window is mandatory in North Sea Whitefish fisheries (Bullough, 2007). A codend with an upper panel made mostly from square mesh (square codend) is mandatory in Baltic cod fisheries (Graham, 2010), escape through open meshes. There have been attempts to use square mesh codends or adding square mesh panels to diamond mesh codends in order to allow undersized fish to escape through the codend (Broadhurst and Kennelly, 1997, Broadhurst et al., 2004, Broadhurst et al., 1999, Grimaldo et al., 2007). The high discard gives a negative impact of this sector of the fishing industry. The issue of selectivity of shrimp fishing gear is therefore of special importance as it constitutes the most important tactic to reduce the problem of discards (Thorsteinsson, 1992; Broadhurst and Kennelly, 1994; Anon, 1996; Rogers et al., 1997; Brewer et al., 1998; Kennelly et al.,