Date Published: September 28, 2018
Publisher: Public Library of Science
Author(s): Iris Segura-García, Thu Yain Tun, Stephen J. Box, Tzen-Yuh Chiang.
Fish are important for food supply, especially in developing countries. In Southeast Asia, including Myanmar, the mud crab fishery is an important livelihood that represents a valuable source of income and food to coastal communities. However, the increasing demand for mud crab in domestic and international markets and poor management has generated concern about the status of this fishery across Southeast Asia. In this region, at least four species of mud crab in the genus Scylla are recognised but their correct identification and occurrence remain to be fully explained. Relying on accurate taxonomic identification of mud crab species represents the cornerstone of the successful implementation of management plans as life history biology and relative exploitation rates may vary by species due to gear susceptibility. Toward this aim, tissue samples from mud crabs were collected from four fishing communities of the Mergui archipelago, in the Tanintharyi region of southern Myanmar. All crab samples were DNA barcoded for species identification through sequencing. This study is the first genetic characterization of the mud crab fishery in Myanmar and revealed that Scylla olivacea was the only species found in the sampled fisheries of the Tanintharyi region. The populations studied across the Mergui archipelago did not show evidence of genetic structure, but gene flow appeared to be limited among conspecifics from neighbouring countries.
Mud crabs in the genus Scylla (de Hann 1833) are large edible crustaceans associated with mangroves throughout the Indo-West Pacific region [1,2]. They are a valuable marine food product in domestic and export markets that constitute an important source of income for coastal fishing communities [3,4]. Unfortunately, the lack of adequate management to regulate catches by small-scale fisheries has generate a concern about the status of this fishery. The knowledge of the species molecular identity, composition and population dynamics of the fishing stocks are still scarce, thus precluding the appropriate management actions.
These results suggest Scylla olivacea is the main or only species harvested in the mud crab fishery in the Mergui archipelago. Moreover, S. olivacea exhibits an extensive gene flow among the populations, but restricted gene flow among neighbouring countries Therefore, the population of S. olivacea in the Mergui archipelago may be susceptible to local depletion from overfishing as neighbouring countries may not contribute to replenish its fishing stocks, and so local management of the Myanmar mud crabbing is fundamental. These findings represent a critical baseline for further studies to assess the effect of fishing, overfishing, pollution, and habitat loss on the mud crab population and on the levels of genetic diversity, which is directly affected by the ability of the species to successfully adapt to natural and anthropogenic changes in the environment.