Occurrence of the blue crab Callinectes sapidus, Rathbun, 1896, and its fisheries biology in Bardawil Lagoon, Sinai Peninsula, Egypt

This study reports the yearly occurrence and the biology of fisheries belonging to the blue crab Callinectes sapidus (Rath.) in the catch yield of Bardawil Lagoon (BL) in Sinai Peninsula, Egypt over the past 15 years. The study shows that between the years 2000–2015 the crustacean fishery increased (pooling both shrimp and crabs) with fluctuations from 40% to 63% of the total production of the lagoon. The crab yield, during this period, increased from 19% to 42% of the total lagoon production. Moreover, the results show that the crab catch of BL is composed mainly of two crab species Portunus pelagicus (L.) and C. sapidus (Rath.). The latter is considered the most dominant in the crab yield with 85% of the total crab production, while C. sapidus is only 15%. The size of C. sapidus ranged between 65 and 155 mm (carapace width) with a dominance of the class size 105 mm. Furthermore, the ratio of C. sapidus males to females was in favor of males. The regression of width–length relationship showed a marked deviation from the isometric growth. Length–width and body weight regressions also showed deviations from the isometric growth and the analysis of the covariance. This indicates the significant difference between sexes in respect to length weight relationship. The interrelationships between width–length and propodus length and depth of males and with abdomen in females of C. sapidus suggested that in most conditions the relationships were positive and highly significant. This study shows the first insights on the status of C. sapidus in Bardawil Lagoon, Egypt.