Determining the Age and Growth of The Spotted Seatrout (Cynoscion nebulosus) Using Marginal Otolith Extraction Techniques

The identification of essential fish habitat (EFH) is important to understanding population dynamics and connectivity in marine fishes. One method of identifying these critical areas is by comparing growth rates among these habitats – faster growth rates are thought to indicate essential habitats. The spotted seatrout (Cynoscion nebulosus) is a common resident of south Texas bays, and represents the number one recreational fishery in the area.  Recent declines in local populations have elevated the need for identifying essential fish habitat for this species.   This study was designed to compare ages and growth rates of spotted seatrout among three south Texas bays using otolith microstructure to identify EFH.  Specimens were caught from Aransas Bay, Upper Laguna Madre, and Corpus Christi Bay using hook-and-line sampling. Sagittal otoliths were extracted and aged using annular rings.  Growth rates of specific year classes were compared among bays by measuring the distance between annular rings.  The observed ages ranged between 1-5 years and standard fish lengths were between 328 and 575 mm. Overall Age and growth results were comparable with other published studies of spotted seatrout from Florida and the upper Texas coast.  Growth rates for all bays showed initial rapid growth that then decreased as age increased.  Findings from this study provide useful and previously undescribed records of growth curves for spotted seatrout in these three south Texas bays. This information can help fishery managers identify areas of faster growth rates that represent essential fish habitat, enabling better conservation for this important fishery.