Using Sturgeon Behavior to Determine Fish Passage and Ecosystem Flow Restoration Opportunities on the Savannah River

Monitoring movement patterns and habitat use of shortnose sturgeon (Acipenser brevirostrum) is enabling adaptive management of the Savannah River, GA . Telemetry data is being used by resource managers to make informed decisions about how to balance the need for river flows that support species and habitats with human uses of the Savannah River.  Damming for flood control and hydropower, modifications of the river channel for navigation, declines in water quality and overfishing are all human-induced factors that have contributed to the decline of Savannah River shortnose sturgeon. Changes in flows due to dam operations affect the only remaining shoal habitat in the river, inundation of one of the most expansive floodplain forests in the southeast, and critical freshwater inflow into a highly productive estuary that supports trust resources such as the federally endangered shortnose sturgeon.  In 2003, The Nature Conservancy initiated a collaborative effort with the U.S. Army Corps of Engineers, and other state, federal and NGO partners to define relationships between biota and flow regime and begin adaptive management of the Savannah River for both human and ecosystem benefits.  In 2006-2009, multiple high flow pulses were released to benefit floodplain and estuarine ecosystems and to pass fish through a lock and dam that blocks access to historic spawning grounds.  During that time, thirty-four adult shortnose sturgeon were tagged with acoustic transmitters and tracked to monitor fish passage and habitat use.  Nine tagged sturgeon were tracked making spawning runs as early as mid-February.  Although no tagged fish were located above the dam, analysis of the locations of tagged spawning individuals led to the identification of potential spawning habitat below the dam and verified the need for fish passage modification at the dam.  This study enabled biologists to: assess the quality of potential spawning habitat during drought years; determine movement and habitat use of the estuary; and document shortnose sturgeon migrations between the Savannah River and other rivers in South Carolina.  This effort established a collaborative partnership that has leveraged support for a larger scale, multi-state study of sturgeon and helped improve resource manager’s understanding of ecosystem flow requirements used for the adaptive management of the Savannah River.