Spatial and temporal distribution of juvenile Gulf Sturgeon in the Pearl River, Louisiana, and adjacent estuaries of the Gulf of Mexico

Objective: Acoustic telemetry was used to examine the spatial-temporal distribution and anadromous migration pattern of juvenile Gulf Sturgeon Acipenser desotoi within the Pearl River and associated coastal estuaries of Louisiana and Mississippi. Methods: Acoustic transmitters were surgically implanted in 52 juvenile Gulf Sturgeon (<890 mm fork length) from the Pearl River between 2016 and 2019. Sturgeon were monitored on 247 acoustic receivers in the lower Pearl River and adjacent estuaries across numerous partnering arrays. Result: Juveniles were detected on receivers from Lake Pontchartrain, Louisiana, east to Bay St. Louis, and Biloxi Bay, Mississippi. The 3-year study found that juvenile Gulf Sturgeon migration in the Pearl River occurred on cycles similar to those reported from other populations. Juveniles were rarely observed in the estuary and nearshore marine environments from May through mid-October of each year, during which time most sturgeon inhabited the Pearl River. Conversely, most of the juveniles inhabited coastal estuaries from December through February of each year and were rarely observed in freshwater environments during this period. Migration from the river into the estuary occurred during late-October through November, and migration from the estuary into the river occurred in March and April. Distribution patterns varied spatially within the river and estuary ecosystems during each phase of migration. Tagged juveniles occupied the lowest 40 km of the Pearl River while in freshwater, and they occupied the northeastern shoreline of Lake Pontchartrain and Bay St. Louis while in the estuary. Interestingly, juveniles seemed to target specific areas in the estuary during winter that were farther away from the mouth of natal rivers than has been previously reported. Conclusion: This study provides a new assessment of juvenile Gulf Sturgeon migration and seasonal distribution for the Pearl River and provides important information for designing and assessing the potential benefits and challenges of habitat restoration for Gulf Sturgeon.