The main goals of this project are to refine reproductive assessments of white shrimp and to improve our understanding of the sensitivity of reproductive phenology to environmental variability.
Specific project objectives include strengthening our understanding of the relationship between macroscopic characteristics and histologically-based metrics of reproductive condition (especially the identification of individuals that have previously spawned) for female white shrimp, developing a visual guide to standardize field-based macroscopic assessments of reproductive status in female white shrimp, investigating existing datasets to determine temporal trends in the timing of reproductive development and its relationship with environmental conditions and climate indices, field-testing standardized reproductive status assessment methods for female white shrimp in South Carolina and Georgia, and documenting spatial variability in the onset of reproductive activity in female white shrimp across South Carolina and Georgia.
This project will provide fishery managers with access to more detailed biological data, supporting a more informed decision-making process regarding the opening of the spring commercial shrimp season.
Project Findings
In 2022, female white shrimp were collected on a weekly basis from mid-March to mid-June in Charleston Harbor, resulting in a total of 516 adult specimens meeting requirements for analysis; shrimp were assessed both macroscopically and microscopically to assess reproductive status. After the onset of spawning in late April, macroscopic observations tended to overestimate the spawning activity relative to microscopic observations. Agreement between the observation techniques declined throughout the spawning season. Using these results, a best practices guide was developed for macroscopically identifying ovarian development in field conditions.
In 2024, over an intensive four-day period of sampling, a total of 587 female white shrimp that were collected across six estuaries in S.C. and six estuaries in GA met requirements for analysis and were again examined macroscopically and microscopically. Samples informed the standardization of a new visual guide to macroscopically categorize white shrimp reproduction, provided data on the biological indicators of reproduction in white shrimp, and resulted in detailed descriptions of how the timing of reproductive activity may differ latitudinally across the South Carolina–Georgia coast. Overall, the macroscopic approach tended to underestimate the reproductive phase when compared to the microscopic approach.
The team also investigated trends in the timing of female reproductive development and its relationship with environmental conditions using existing datasets from the Southeast region spanning 1979–2023. Analyses revealed a significant trend of earlier spawning onset by 4–5 days per decade, driven in part by shifting climate, oceanographic circulation, and regional weather patterns.
Resulting Publications
Mitchell A., Wagner, G., Kingsley-Smith, P., Brunson, J., Kendrick, M. (2024). “Characterizing reproductive development in female white shrimp Penaeus setiferus (Decapoda: Dendrobranchiata: Penaeidae) in South Carolina, USA,” Journal of Crustacean Biology, Volume 44, Issue 3, September 2024.