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

Abstract

AbstractAge‐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 sampling years could be used as surrogates for regions where samples were not obtained in a given year.Received February 7, 2012; accepted June 5, 2012