Reproductive biology and growth of the Western School Prown, Metapenaeus dalli, in a large Western Australian Estuary

Abstract

During the summer, one-year-old western school prawns (Metapenaeus dalli) congregate and spawn in reduced-salinity (< 10 g kg-1) regions of the Murray River, a tributary of the large Peel-Harvey estuarine system in Western Australia. Although some 1 + prawns are found into the following spring, few if any survive or remain in the system until the next spawning season. Growth is highly seasonal and females attain a greater carapace length than males by the end of the first year of life (18 v. 14 mm). Changes in the incidence of spermatophore deposition, gonadosomatic index (GSI) and ovarian stage during the spawning period are described. Although the timing of recruitment of O+ prawns could be related to the sharp peak in the incidence of spermatophore deposition and GSI in 1985-86, such relationships were not so clearly defined in 1987-88 when the incidence of spermatophore deposition remained above 9% for over twice the length of time.