Genetic diversity monitoring of Chiloscyllium plagiosum from coastal Xiamen between generations

Chiloscyllium plagiosum (Bennett, 1830) is a productive shark species found in the Chinese coastal waters. However, populations of this species have declined due to factors such as increased fishing pressure, habitat loss, and habitat destruction. Therefore, monitoring the genetic signatures of C. plagiosum is an urgent need. Using the coastal waters of Xiamen as the research area, C. plagiosum specimens were collected from 2017 to 2021 to detect changes in their genetic diversity across several years. The genetic diversity of C. plagiosum from the coastal area of Xiamen fluctuated between generations and remained relatively high in general compared to that of fishing waters which is possibly related to the coastal waters of Xiamen being in a protected marine area where C. plagiosum is not affected by fishing pressure. The genetic differentiation between C. plagiosum populations in different years was extremely low, primarily arising from within the population, indicating that the recruitment stock of C. plagiosum in the coastal waters of Xiamen was sufficient for adequate gene exchange. The results of the historical demography revealed that a population expansion of C. plagiosum had historically occurred, and its effective population experienced rapid growth after expansion. The coastal waters of Southern Fujian are the center of the expansion of the ancestral C. plagiosum population along the southern coast of China; therefore, the genetic diversity and genetic structure of this species require further study to understand the changing patterns of its genetic characteristics, prevent the decline of its germplasm resources in the wild, and protect fishery resources.