Reproductive biology of the Lessepsian migrant shrimp scad Alepes djedaba (Forsskal, 1775) from the Egyptian Mediterranean Sea coast

The shrimp sacd, Alepes djedaba is a dominant species of genus Alepes in the purse seine catch of Damietta and Port Said landing sites on the Egyptian Mediterranean Sea. It represents a commercial species in Mediterranean Sea fisheries. A total of 718 specimens were collected from January to December 2019. The sex ratio M: F was 1.0:1.24 as the total sample contained 321 males and 397 females. The P-value of the chi-square test showed a highly significant difference between both sexes. Macroscopic and histological examination of gonads and monthly gonado-somatic index distribution revealed that A. djedaba has a prolonged spawning season extending from April to November with a peak during May. The lengths at first maturity were 16.0 and 16.7 cm for males and females respectively. A. djedaba is distinguished by high fecundity as the absolute fecundity ranged from 31680 to 336675 with an average of 134940.6 eggs and the relative fecundity ranged from 980.8 to 2683.9 with an average of 2152.2 oocytes g^-1