Non-indigenous giant mud crab, Scylla serrata (Forskål, 1775) (Crustacea: Brachyura: Portunidae) in Malaysian coastal waters: a call for caution

Introduction of non-indigenous species into a well-established ecosystem can be detrimental, resulting in both ecological and economical damage. Two specimens of giant mud crab, Scylla serrata were found for the first time in two geographically distinct mud crab landing sites (Matang Mangrove Forest Reserve, Perak and Kota Marudu Mangrove Forest, Sabah) in Malaysia. Their identities were confirmed using a combination of morphological, morphometric and molecular (partial COI gene) analyses. Scylla serrata is regarded as non-indigenous species within Malaysian coastal waters as this is the first confirmed report of their occurrence in Malaysia and no established population was found in both landing sites. Accidental release or escape was considered as the possible vector for the introduction of the two specimens found in this study as frequent import of S. serrata from other countries were reported in both landing sites. Urgent intervention is needed to prevent further introduction and possible establishment of S. serrata population in Malaysian coastal waters.