Some biological studies on the Egyptian crab Portunus pelagicus (LINNAEUS, 1766)
Abstract
The fishery of the Egyptian red crab Portunus pelagicus (Linnaeus, 1766) has grown considerably and now is commercially well exploited. Maturity of both sexes was determined. Five stages of ovary maturation (immature, maturing, late mature, berried and spent stages) were determined for female. Breeding season of the crab was found to be during winter-spring and continues to the end of summer. All females of the studied species were found fully ripe at 14.5 cm carapace width and can lay viable eggs after reaching 9.0-10.0 cm carapace width. The puberty molt i.e transition from pre-puberty to post-puberty phase occurs at 9.5 cm carapace width for both sexes; and females can spawn at least two times a year.
A linear relationship between fecundity and carapace width was noted. The lowest number of eggs per female observed was 75167 from a 11.1 cm carapace width specimen and the highest was 812738 from a femme with 13.6 cm carapace width... The crab feeds on a wide variety of food items, and its diet includes many kinds of marine plants, as well as molluscs and crustaceans. The most intensive feeding activity, occurs during the April-June period.
