Species Status of Ragworm Populations (Nereididae: Tylorrhynchus Sp.) Exploited as a Human Specialty Based on Their Molecular Analyses in the Northern Coast of Vietnam

Abstract

In the traditional culinary culture of Vietnam, the ragworms (Nereididae) are an ancient and well-known delicacy (Chả rươi in Vietnamese) of great nutritional and economic value. In order to determine their species status, distribution, and sustainable control, a comparative molecular genetic analysis was carried out in 2018--2019. It comprised of ragworm populations along the northern coast including Quang Ninh, Hai Phong, Hai Duong, Thai Binh and Nam Dinh, 20.0, 14.5, 34.0, 26.0 and 17.0 km from the sea, respectively. We found that all of them belong to one and the same species named Tylorrhynchus heterochaetus (Quatrefages, 1866). The ragworm in the Tu Ky area of Hai Duong province has the farthest distribution in the mainland, and was among the ragworm groups with the largest morphological measurements. Salinity and inland environmental conditions are likely factors influencing the morphological development of ragworm populations in this area. This may be the reason Tu Ky ragworms have been labelled a specialty dish in Vietnam dating back to ancient history.