Biology of penaeid prawns in the Suez Canal lakes

Abstract

A study was made from January 1988 to March 1989 of the penaid prawns in the Great Bitter Lake and Lake Timsah located in the central part of the Suez Canal. Two species of Red Sea origin were investigated,Metapenaeus stebbingi andTrachypenaeus curvirostris; the former is by far the commoner. Both species displayed seasonal breeding over the period April to October, with peaks in the early and late parts of the season.M. stebbingi had two main cohorts each year. A spring-spawned cohort survived 16 mo, and attained modal sizes of 23 mm carapare length (CL) for females and 16 to 17 mm CL for males. The autumn-spawned cohort survived 13 mo, and reached modal sizes of 20 mm and 15 mm CL for males and females, respectively. The reasons for the success ofM. stebbingi in the Canal lakes, in contrast to other “Lessepsian” penaeids which have flourished in the Mediterranean Sea, have been considered. The main factors are that it is essentially a shallow-water species, with excellent tolerance of salinity variations and adverse environments. However, the Canal lake populations have smaller maximum sizes, and mature earlier, than those in open seas.