Regional Variation in Growth and Mortality of Spotted Seatrout in the Western Gulf of Mexico

Abstract

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.

Environmental DNA compliments traditional sampling for monitoring fish communities in a Texas estuary

“…One of the benefits of traditional long‐term fisheries sampling programs is that the data obtained can be used to track single‐species abundance through time. For instance, the TPWD has used long‐term species accounts from both gears deployed in this study to track abundance and distribution of multiple recreationally and commercially important species (e.g., Red Drum, Anderson et al 2023; ladyfishes, Williford et al 2022; Gray Snapper Lutjanus griseus , Anderson et al 2022; Black Drum, Olsen 2014). Regarding eDNA as a comparative method, the relationship between the number of sequence reads that was obtained in a single sample and the numerical presence and recency of taxa that were observed via traditional sampling is often unclear and confounded by either environmental or methodological processes.…”

Estimating fish mortality rates from catch curves: A plea for the abandonment of Ricker (1975)'s linear regression method

“…(2021), Anderson et al . (2022), Tsai and Huang (2022), Yamamoto and Katayama (2022), Andrade et al . (2023), He et al .…”