Gray snapper (Lutjanus griseus) is a common reef fish inhabiting the western Atlantic Ocean. In estuaries of the Southeastern United States, such as Mosquito Lagoon (ML), Florida, oyster reefs, seagrass, and mangrove shorelines are vital nurseries, also known as essential fish habitat (EFH), for juvenile and sub-adult fish. However, EFH in Mosquito Lagoon has declined from historic levels. To mitigate these losses, oyster reef and living shoreline restoration projects have occurred to putatively increase the availability of EFH. For gray snapper in ML, past studies have assessed local habitat preferences and trophic structure, but the biotic and abiotic factors influencing age and growth rates have not been quantified. To address this knowledge gap, this study aims to quantify the mean age and growth rate of gray snapper in ML, and investigate if prey and/or other environmental factors (e.g. abiotic/biotic conditions, time, and location/site status) impact age and growth at both lagoon and habitat-specific scales. Results indicate the most common life stage for gray snapper in ML are young sub-adults, with living shoreline habitats having a greater proportion of juveniles and oyster reef habitats having a greater proportion of young sub-adults. Growth was correlated with prey abundance, location/site status, and water properties (i.e. water temperature and dissolved oxygen), with said environmental factors outperforming stable isotope and gut content variables in model comparisons. Gray snapper age was also correlated with growth in all of the most parsimonious models, suggesting future research should consider including life history-related variables and weight-length relationships when investigating the environmental or trophic influences on gray snapper growth. Collectively, this study increases our fundamental understanding of gray snapper population dynamics and provides insight that can be used subsequently to benefit the management of recreational and commercial fisheries in the Southeastern US.
Dr. Geoffrey S. Cook, Committee Chair.
The public is welcome to attend.
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