Assessing possible a breeding population as snook numbers increase in South Texas

Rising ocean temperatures due to climate change have led to steady increases in the frequency of tropical fishes as their ranges expand into formerly cooler waters. In South Texas, common snook (Centropomus undecimalis), a tropical fish species known to be intolerant of colder climates, are becoming more numerous. However, it is uncertain if they have established a breeding population. Therefore, this study will: 1) investigate if common snook have established a breeding population in South Texas, 2) determine amounts of neutral genetic variation and how it is distributed, and 3) identify essential habitat using Geospatial Information System (GIS). In the summer and fall of 2012, DNA samples from adult snook and young-of-the-year (YOY) within a single bay (Lower Laguna Madre or LLM in south Texas) will be collected and analyzed for at least 10 species specific microsatellite markers using standard population genetic techniques and statistics. In addition to describing genetic variation in LLM, parentage analysis of the YOY will determine if they could have been produced by local adults, indicating a local breeding population. Genetic data will be overlapped with environmental and hydrology data in GIS using the "Landscape Genetics GIS Toolbox." We will use such GIS analyses to determine essential snook habitat. We expect this project to be complete by August 2013, but preliminary analyses will be presented. Currently, information on common snook in Texas is highly limited. This study will provide necessary information for managers to properly regulate the growing recreational fishery in Texas for this species.