Tracking the migration and distribution of Caspian Kutum (Rutilus kutum, Kamenskii, 1901) along the southern coastline of the Caspian Sea: Using stable isotope analysis

Abstract Evaluating management strategies for fish catch development requires knowledge of movement patterns and their spatial distribution. The Caspian kutum (Rutilus kutum, Kamenskii, 1901) is an important commercial species throughout the southern coasts of the Caspian Sea. Stable isotope ratios are powerful indexes that simplify the understanding of the migration of aquatic animals. This research determined the stable isotope ratio of carbon (δ13C) and nitrogen (δ15N) for Rutilus kutum movement at 10 sites along the southern coastline of the Caspian Sea from January to December 2017. Spatial and temporal variations in stable isotope values of the coastal communities in the Caspian Sea remain poorly understood. These findings suggest that individual variation, but with a strong overall decline in δ13C and increasing in δ15N and δ13C/δ15N ratio with age, too. These isoscpes showed that the δ15N ratio increased and δ13C decreased from the east (Gomishan) to the west (Astara).