The Alabama sturgeon (Scaphirhyncus suttkusi) is a slender freshwater fish and opportunistic bottom feeder. Its historic range encompassed all major rivers in the Mobile Basin below the Fall Line, including the Alabama, Tombigbee, and Cahaba River systems. Recent collections have been restricted to the lower Alabama River below Millers Ferry Lock and Dam to the confluence of the Tombigbee River and in the lower Cahaba River near its confluence with the Alabama River. The last capture of an Alabama sturgeon was on April 3, 2007, by biologists at the Alabama Department of Conservation and Natural Resources (ADCNR). The Alabama sturgeon is one of the rarest and most endangered fish in the nation and may be close to extinction. It was listed as an endangered species on May 5, 2000 (65 FR 26438)
Very little is known of the habitat requirements of the Alabama sturgeon. Based on capture data, it inhabits the main channel of large coastal plain rivers of the Mobile River Basin. Most specimens have been taken in moderate to swift current at depths of 6 to 14 m, over sand, gravel or mud bottom. Similar preferences have also observed in shovelnose sturgeon. Most historical and recent sturgeon capture sites are at or near features that include rock walls, river channel training devices, deep pools, mussel beds, confluences with tributaries, and/or stable sand and gravel bottoms. The presence of mussel beds represents stable channel habitats that are likely important feeding areas for sturgeon, while deep pools and confluence areas with tributaries may be used as thermal refugia during times of low flow.
Alabama sturgeon are generally considered opportunistic bottom feeders that primarily eat aquatic insects, plant material, and mollusks. Commercial fisherman report that sturgeon have been captured on trotlines with a variety of bait, including poultry parts, fish, and commercially prepared bait. Juvenile shovelnose sturgeon prefer feeding in sandy substrates and actively avoid gravel areas, and juvenile Alabama sturgeon may share this feeding preference.
Adult shovelnose sturgeon and juvenile shovelnose sturgeon are more active at night, but their habitat preferences do not vary from day to night. Alabama sturgeon may have similar habitat preferences. This type of behavior was also observed in juvenile shovelnose sturgeon and may apply to Alabama sturgeon. One Alabama sturgeon that was tagged and tracked from April 2007 to June 2008 displayed varied movement patterns. During the summer months, the fish was stationary and resided around the confluence of a small spring-fed stream called Sizemore Creek in the lower Alabama River. Water temperatures in Sizemore Creek were typically 4-5? cooler than the Alabama River, which suggest the fish was using this area as a thermal refuge. Movement was greatest during the spring and may indicate that the fish was attempting to migrate upstream to spawn.. The greatest movement was associated with water temperatures between 16 and 21?, and no clear correlations were made between upstream movement and increased river discharge.
The Alabama sturgeon is a slender freshwater fish that grows to about 30 inches (0.7 m) in length.
An adult Alabama sturgeon weighs 2-3 pounds.
Its eyes are larger and extend into the head width more than those of a shovelnose sturgeon. Its back and most of its fins are brownish orange, while its sides are golden-yellow and its belly is creamy white.
River sturgeons (Scaphirhynchus spp.) require extensive areas of flowing water habitats to complete their life cycle. Adults will often migrate upstream to spawn. Alabama sturgeon larvae drift downstream for 12-13 days after hatching. Pallid sturgeon larvae drift downstream for 11 days and can drift for more than 125 miles before they settle in the bottom of the river. Alabama Sturgeon may require some minimum distance of flowing river conditions for larval development and for sustainable recruitment of the species.
Life span of the Alabama Sturgeon is unknown. Although few individuals probably exceed 12 to 15 years of age, it is possible the species may live longer.
Sexual maturity of the Alabama sturgeon is believed to occur at 5-7 years of age. Spawning frequency of both sexes is likely influenced by food supply and fish condition and may occur once every 2-3 year years. As with most riverine sturgeon, spawning is likely initiated by environmental cues such as temperature, photoperiod, and an increase in river discharge during the late winter and early spring. The development of numerous large-river impoundments in the Mobile Basin may influence these cues.
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