New insights into marine migration and winter habitat of Gulf sturgeon
Migrations and movements of Gulf sturgeon Acipenser oxyrinchus desotoi were determined using satellite pop-up archival transmitting (PAT) tags and acoustic telemetry. Adult Gulf sturgeon from four rivers in northwestern Florida were caught with gill nets and were tagged with PAT and acoustic tags in the fall of 2001 and 2002. PAT tags were programmed to release in early February 2002 and 2003 to provide information about location of late-winter marine habitats. However, only 5 of 25 provided meaningful location information. Three of the PAT-tagged fish were relocated acoustically near the PAT tag pop-up locations, one of which was in Choctawhatchee Bay. Acoustic searches near Gulf of Mexico pop-up locations led to acoustic relocation of one nonreporting PAT-tagged fish and five fish tagged with acoustic transmitters only. Many of these fish were relocated on several dates in late winter, and many (including fish from the Yellow, Choctawhatchee, and Apalachicola rivers) were concentrated in a 25-km stretch of the Florida Panhandle coast, within 2 km from shore, and in depths less than 6 m. A fish that had been tagged with a PAT tag in the Yellow River was acoustically relocated in the concentration area and then in the Choctawhatchee River the following summer. It returned to the concentration area again the next winter and returned to the Choctawhatchee for the second summer. An acoustic-tagged fish was relocated very near a PAT tag pop-up location about 30 km south of the Suwannee River, within 12 km from shore, and in depths of 3-4 m. Pop-up locations and acoustic relocations showed that the Gulf sturgeon had migrated distances of at least 30180 km. These findings indicate a pattern in which Gulf sturgeon migrate considerable distances along the coastline, sometimes to specific areas of concentration, sometimes mixing with other populations, and primarily utilizing shallow (2-6 in), nearshore areas as late-winter habitats. This pattern is similar to that reported by others in this volume for Atlantic sturgeon Acipenser oxyrinchus and for green sturgeon A. medirostris.