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Large Gulf Sturgeon Collected and Released in Mobile Bay
March 13, 2006
Biologists from the Geological Survey of Alabama (GSA), Alabama Wildlife and Freshwater Fisheries Division (WFFD), and the U.S. Fish and Wildlife Service (USFWS) caught and released a 160 pound Gulf sturgeon near Fairhope in Mobile Bay on Feb. 21, 2006. A small tag found near the dorsal fin indicated the USFWS had tagged the fish in the lower Choctawhatchee River in northwest Florida in 1999.
The range of the Gulf sturgeon extends along the northern Gulf coast from Lake Ponchartrain in Louisiana to the Suwannee River in Florida. This is an anadromous fish species, meaning individuals spend most of their lives in salt water and migrate into freshwater rivers to spawn. After spawning, they remain in fresh water for several weeks before returning to salt water. Newly hatched sturgeon remain in fresh water for several months before moving downstream into bays and estuaries. Adult sturgeon do not feed while in fresh water.
In the late 1800s and early 1900s newspaper reports and photographs documented that large Gulf sturgeon exceeding several hundred pounds inhabited the Alabama, Cahaba, Coosa, and Tallapoosa Rivers. The species eventually disappeared from the area due in part to over-harvest and the construction of high-lift locks and dams, which blocked upstream migrations to inland spawning habitats. Fearing species numbers would continue to decline throughout the range, the USFWS listed the Gulf sturgeon as a threatened species under the endangered Species Act in 1991.
In 2005, the WFFD and GSA initiated a cooperative study with funding from the State Wildlife Grants program to gather information on Gulf sturgeon numbers, movements, and life history in Mobile and Perdido Bays and their contributing rivers. Sturgeon will be collected, measured and weighed from March through April. Each fish will receive an ultrasonic tag that transmits a distinctive signal for 36 to 48 months. Tracking will range throughout the study area, in an effort to find the tagged fish. If a fish is detected, its location will be recorded on a Global Positioning System receiver, and all of its locality data will be used to create a map showing movement patterns. Water quality and bottom data collected at each site will be used to characterize sturgeon habitat in Alabama waters.
A second goal of the study is to identify Gulf sturgeon spawning habitats in the Alabama and Tombigbee Rivers. Egg collecting devices will be placed at various locations in the lower reaches of both rivers and checked every two to three days from March through April. Eggs will be removed and placed in aquariums to hatch. A few eggs will be used for DNA tests. Hatched larvae will be transported back to their original collection site.
This study is intended to contribute to the overall understanding of the life history requirements of this unique fish throughout the Gulf coast. The eventual goal is to reverse its decline and work toward its removal from the need for Endangered Species Act protection.
The Alabama Department of Conservation and Natural Resources promotes wise stewardship, management and enjoyment of Alabama’s natural resources through five divisions: Marine Police, Marine Resources, State Parks, State Lands, and Wildlife and Freshwater Fisheries.
From Left: Scott Mettee and Stuart McGregor of the Geological Survey of Alabama and Jerry Moss of the Wildlife and Freshwater Fisheries Division of the Department of Conservation with the Gulf sturgeon caught and released from Mobile Bay on February 21, 2006.