Isotopic Composition of Otoliths As a Stock Delineator for King Mackerel (Scomberomorus cavalla)

The fish otolith has primarily been used to age fish, but as a metabolically inert environmental recorder, it has become useful for stock identification, reconstruction of temperature and salinity history, and determination of trophic position. For this study, oxygen, carbon and strontium isotopic analysis was done on otoliths of 60 King Mackerel (Scomberomorus cavalla), half from the Gulf of Mexico stock and half from the Atlantic stock.  Additionally, transects were taken from a selection of the population to show lifetime trends in isotopic indicators in the fish from each population. The results help describe differences in diet and habitat waters and enable us to determine whether they are in fact two separate populations, or one homogenous population, and thus how they should be managed.