Stability of elemental signatures in the scales of spawning weakfish, Cynoscion regalis

We quantified elemental signatures in scales of ages-1 and -2 weakfish, Cynoscion regalis, collected during the spawning season in Pamlico Sound, Chesapeake Bay, and Delaware Bay in 1998. We compared these signatures with elemental signatures from scales of juvenile weakfish collected while still resident in natal estuaries at five locations along the Atlantic coast in 1996 and 1997. Although Mg/Ca and Mn/Ca were lower in the juvenile portion of scales from adults compared with scales from juvenile fish, Sr/Ca and Ba/Ca were similar in the three age groups. We compared scale and otolith chemistries from juveniles and adults to determine if relative concentrations of elements/Ca in scales remained consistent, even if absolute levels were altered. Scale Mn/Ca and Ba/Ca remained correlated with those in otoliths of adult fish. Finally, we examined the ability of elemental signatures in scales to act as natural tags of natal estuaries in spawning weakfish. Allocation of fish to natal estuaries based on geochemical signatures in scales and otoliths from age-1 fish was similar; however, allocation was different for age-2 fish. Elemental signatures in scales degraded after the juvenile period and after maturation were insufficiently stable for use as a natural tag of natal origins in weakfish.