Movements of Gulf sturgeon (Acipenser oxyrinchus desotoi) in nearshore habitat as determined by acoustic telemetry

Abstract

Gulf sturgeon were tagged with telemetry tags and were tracked and relocated in fall and early winter of 1996 and 1998 to determine migration patterns and winter feeding habitats after they emigrated from the Suwannee River, Florida, into the Gulf of Mexico. We hypothesized that their migration would generally follow the drowned Suwannee River channel accross the West Florida shelf. Fish left the river in late Oct. or early Nov., about the time river water temperatures fell below 20 C. Tracked and relocated fish moved slowly and remained offshore of Suwannee Sound in nearby shallow (<6 m) marine-estuarine habitats until at least mid or late Dec. The relatively small area (∼115 km2 ) within which fish were consistently relocated in 1998 probably is a critically important feeding habitat because adult Gulf sturgeon, which do not feed while in the river, occupy it for up to half their short (4-5 mo) marine residency. The fish left the area in late Dec. or early Jan., most likely in response to powerful cold front-generated weather conditions (under which, boat-based acoustic tracking is infeasible). A large (1,760 km2) adjacent area was searched for sonic-tagged sturgeon in early Jan. 1999, but only one was relocated (∼50 km northwest of the Nov.-Dec. area). Although we were unable to address the hypothesis that their migration follows the Suwannee paleochannel, the results do indicate that Gulf sturgeon move to yet unknown, distant, late-winter feeding areas of the Gulf of Mexico before returning to the river in spring.