The Spotted Seatrout Cynoscion nebulosus, a year‐round estuarine resident throughout the Gulf of Mexico, is a common mid‐trophic predator across its range and is one of the most popular game fish in Texas. In 1998, the Texas Parks and Wildlife Department initiated long‐term collections of otoliths from Spotted Seatrout encountered in fishery‐independent samples. Here, we use data from those collections (1998–2018) to generate a coastwide growth function and assess regional and temporal variation in growth and mortality. Key findings from this work include (1) sexual dimorphism in Texas that is consistent with previous studies across the species' range, with females exhibiting faster growth rates (growth rate parameter k) and having a greater asymptotic length than males based on coastwide sex‐specific growth functions; (2) relatively fast growth in northern estuaries, as evidenced by estuary‐specific patterns of deviation from a coastwide growth function as well as variability among k‐values from regionalized growth functions; and (3) higher estimates of natural mortality and total mortality in northern estuaries based on regional variation in k and catch‐curve analysis. The third finding was supported by an increase in estuary‐specific mean age of Spotted Seatrout from north to south, suggesting that older fish are more common in southern estuaries. Broadly, significant regional variation in age, growth, and mortality implies a complex underlying demographic structure. Clinal variation in important life history phenotypes of Spotted Seatrout in the western Gulf is consistent with previous studies that have described clinal genetic variation for the species, implying the potential for overlapping but independent subpopulations in the western Gulf of Mexico.
Two species of ladyfish occur in the Gulf of Mexico (GOM), Elops saurus and Elops smithi, that are morphologically indistinguishable except for vertebral counts but can also be identified by mitochondrial DNA haplotypes. Here we expand on previous work, most of which has occurred in Florida, and examine the demography, phylogenetics, geographic distribution, and age—structure of ladyfishes in Texas estuaries. Fishery—independent gill net data demonstrated that ladyfishes increase in abundance from north to south along the Texas coast. The abundance of ladyfishes also increased in Texas waters from 1982–2021, which coincides with recent trends of warmer winters. Genetic data confirmed that both E. saurus and E. smithi occur in Texas waters; however, E. smithi was far less common. Contrary to previous research, we observed higher levels of genetic diversity in E. saurus due to larger sample size and thorough sampling of the western portion of its geographic range. Phylogenetic analysis supported the existence of E. saurus as a distinct species but indicated that E. smithi may be paraphyletic with other species of Elops. Otolith analysis showed that the ages of E. saurus and E. smithi ranged from 0–3 years. The lack of individuals > age—3 suggests that ladyfishes migrate to the offshore GOM at age 3 and do not return to coastal areas. This study enhances knowledge of the biology of ladyfishes in inshore waters of the northwestern GOM. Future management would benefit from expanding this research to the entire geographic range of the genus Elops.
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