STRONTIUM MICROSTRUCTURE IN SCALES OF FRESH-WATER AND ESTUARINE STRIPED BASS (MORONE-SAXATILIS) DETECTED BY LASER-ABLATION MASS-SPECTROMETRY

A laser ablation microprobe with mass spectrometry was used to examine the variability of Sr concentration among and within scales of striped bass (Morone saxatilis). These exploratory studies demonstrated that the technique is capable of showing differences that we relate to environmental conditions. There were marked differences in scale Sr concentrations at high spatial resolution between striped bass from freshwater reservoirs in Tennessee (low Sr) and the Roanoke River - Albemarle Sound estuary system in North Carolina (high Sr). A peak in Sr concentration was found near the scale focus of striped bass collected in the freshwater Roanoke River (but not in scales from reservoir fish) that may identify saltwater parentage or estuarine rearing. In fish from the Roanoke River and Albemarle Sound, we observed spatial variations across annuli that might reflect movements between fresh and saline water. There was a typical Sr profile with depth through the estuarine scales that exhibited a peak of unresolved significance near the inside surface. Laser ablation mass spectrometry of Sr in fish scales appears to be a valuable technique for life history analyses.