BIOLOGY AND POPULATION DYNAMIC OF BLUE SWIMMING CRAB Portunus pelagicus IN BARDAWILL LAGOON, NORTH SINAI, EGYPT

Crabs are considered non-native crustacean species in Bardawill lagoon which
require more studies. Length frequency analysis were used to estimate size distribution, growth,
maturity, mortality and yield per recruit of Blue swimming crab, Portunus pelagicus in Bardawill
lagoon during the fishing season 2016. Samples were obtained from trammel fishing vessels. Carapace
width of 1068 samples ranged from 4.7 to 13.4 cm and total weight from 10.4 to 198.3 g. Size
distribution showed the major portion of the catch ranged of 8 to 10.9 cm carapace width. FiSAT II
computer program was used to estimate the growth parameters as L∞ = 14.3 cm and K = 1.1 yr-1. The
growth performance index (ø’) equal 2.358. Recruitment was extent from June to October. Sex ratio
between male and female were 1.09: 1. The size at first maturity (CWm50) was estimated at 9.1cm.
Total, natural and fishing mortality rates were 4.25 yr−1, 1.6 yr−1 and 2.65 yr−1, respectively. Size at
first capture (CWc50) was 8.6 cm. So, stock of Blue crab in Bardawill lagoon should be controlled by
increased the fishing effort and adding unconventional fishing methods such as traps with traditional
fishing such as trammel, trawlers and gillnetters, as this species may be become dangerous on native
species in region.