A Comparison of Reproductive Potential of Red Snapper: Natural and Artificial Habitats in the Northern Gulf of Mexico

Monday, September 9, 2013
Governor's Hall I (trade show) (Statehouse Convention Center)
Hilary Glenn , Oceanography and Coastal Science, Louisiana State University, Baton Rouge, LA
James H. Cowan Jr. , Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, LA
Few quantitative studies of red snapper (Lutjanus campechanus)reproduction have been conducted on offshore natural hard bottom (NHB) banks in the northern Gulf of Mexico.  Reproductive potential is an important component of fisheries management, but previous studies have focused almost exclusively on artificial habitats (AH).  This study aims to compare AH and NHB, as NHB habitats are thought to be historical centers of abundance for this species.  The gonadosomatic index (GSI) is indicative of energy a fish invests in reproduction per body weight; thus a larger GSI corresponds with a greater reproductive effort.  Red snapper reach peak fecundity at age ages >10 yr, but mature as early as age two.  Other studies found age 2-3 fish dominate AHs whereas older-fish are normally found inhabiting NHBs.  Samples were collected in 2009-2012 from three NHB sites and two AH sites. Mean GSIs were plotted against time to examine seasonal changes in reproductive effort among sites. Preliminary results indicate that NHB sites exhibited higher mean GSI than AH sites (ANOVA, p <0.0001) during peak spawning season.  We hypothesis these difference are attributed to older fish at NHB sites investing less energy on growth and more energy towards reproduction.