Discrimination of Juvenile Red Snapper Otolith Chemical Signatures from Gulf of Mexico Nursery Regions

Abstract Age-0 red snapper Lutjanus campechanus from the 2005–2007 year-classes were sampled in six regions across the Gulf of Mexico (Gulf) to develop nursery signatures from otolith element: Ca ratios (Ba:Ca, Mg:Ca, Mn:Ca, Sr:Ca, and Li:Ca) and stable isotope delta values (δ13C and δ18O). Element: Ca ratios were analyzed with sector field inductively coupled plasma mass spectrometry on dissolved right sagittae; isotope ratio mass spectrometry was employed to analyze pulverized left otoliths for δ13C and δ18O. Otolith chemical signatures were significantly different among regions in each year. Year-class-specific quadratic discriminant function analysis (QDFA) distinguished nursery regions with an accuracy of 82% for 2005, 70% for 2006, and 72% for 2007. However, samples were not obtained from all six study regions in 2005 and 2006. A QDFA of all year-classes combined produced an overall classification accuracy of 70%, thus indicating that region-specific otolith chemical signatures from adjacent samplin...