D3099: Population dynamics and management of apple snails (Pomacea maculata ) in Louisiana crawfish (Procambarus clarkii ) aquaculture.

This study examines environmental factors, trophic interactions, and crop rotation strategies as potential controls for the invasive apple snails (Gastropoda: Ampullaridae) in Louisiana crawfish ponds. Apple snails are native to South America and have been established in Louisiana over the past decade, increasing labor costs and reducing crawfish production. Currently, no effective management strategy has been implemented to control apple snails. The objectives of this study are to (1) evaluate snail population densities in Louisiana crawfish farms, (2) analyze food source competition between snails and crawfish using stable isotopes analysis, and (3) compare snail densities and trophic ecology between ponds planted with rice (C3 plant) and sorghum/sudan grass (C4 plant) as a potential alternative forage. Snail densities were estimated from spring to summer 2024 across multiple farms in Louisiana using a strip transect, quadrant sampling, and crawfish traps. Water quality parameters were recorded, including dissolved oxygen, pH level, salinity, water depth, and water temperature. Biological samples, including snails, crawfish, particulate organic matter, algae, soil, C3 and C4 plants, were collected to perform stable isotope analysis. Survey results suggest that snail activity increases in late spring, reaching a peak in June. Dissolved oxygen measurements reveal a negative correlation, indicating that lower oxygen levels may be associated with snail abundance. Differences were detected in feeding trials where snails consumed more sudan grass hybrid than rice, suggesting a preference for C4 forage. This study provides valuable information for developing a potential management strategy to control the invasive apple snail in Louisiana crawfish ponds.