Regional Differences in Red Snapper (Lutjanus campechanus) Age and Growth Across the Gulf of Mexico

In the Gulf of Mexico (GOM), red snapper (Lutjanus campechanus) is managed as one unit stock with separate assessments for sub-units east and west of the Mississippi River. Further evaluation of red snapper life history characteristics across the GOM is needed to elucidate the differences between the management sub-units. We compared red snapper morphometrics, age, and growth parameters collected from recreational catches across the US waters of the GOM in 2009 and 2010. We sampled from six major recreational fishing regions across the GOM: South Texas (n=348), North Texas (n=224), Louisiana (n=268), Alabama (n=204), North Florida (n=463), and South Florida (n=301). Ages were obtained from otolith sections and ranged from two to 33 years. Across all of the regions, red snapper were young (mean age of 4.8 years), representing the strong recruitments of 2004, 2005 and 2006. Red snapper exhibited a truncated age structure with few fish older than six years (3.95%). Total length, total weight, and age-frequency distributions differed significantly among the regions. Small, fast-growing individuals dominated the recreational catches from South Texas, North Florida and South Florida, whereas larger, slower growing red snapper constituted the majority of the Alabama and Louisiana recreational catches. Also, the recreational catches of red snapper in the eastern regions (North and South Florida) were comprised of younger red snapper than in the harvests from the north-central and western GOM regions. Red snapper from the Texas regions and North Florida were smaller at age than red snapper from South Florida, Louisiana and Alabama. Our data support previous reports that red snapper from Texas are consistently smaller in length and weight at age than red snapper in Louisiana and Alabama. However, our data indicate that red snapper in Texas have a higher proportion of slightly older (>6 years) individuals. Demographic variation in size and growth rates may result from differences in environmental factors, fishing pressure, and management regimes among the regions, as well as localized population responses to fishing pressure. These results also indicate that there is a decline in the frequency of larger, older red snapper in recreational catches. Comparison of the demographics and growth parameters from this study will help elucidate trends in region-specific age and growth information for red snapper, and can be used to further evaluate the need for management sub-units.