An improved understanding and reporting of the mud crab genotype has led tobetter understanding of their population structure. For example, while Madagascan and South African populations of S. serrata could be separated, populations of mud crabs from six South African estuaries were reportedly homogeneous. Similarly, in Australia, a mitochondrial coding gene for S. serrata was used to identify regional haplotype differences in populations, one of which was related to the natural physical barrier of the Torres Strait. Microsatellite markers are now available for mud crabs and can be used to characterize populations of both S. serrata and S. paramamosain, and assist in parentage determination. Microsatellite markers were used to assess the genetic diversity of S. serrata populations from five Micronesian islands, finding that no significant difference could be found between them, even though they were geographically widely distributed.