This article presents population and biology facts related to gulf sturgeon, Acipenser oxyrinchus desotoi.
The gulf sturgeon is a subspecies of the Atlantic sturgeon and was first described and recognized as a subspecies in 1955. Besides genetic differences, gulf sturgeon differ from the Atlantic sturgeon in relative head length and pectoral fin length, shape of dorsal scutes (bony plates), and length and position of the spleen. It is very difficult to visually differentiate gulf from Atlantic sturgeon. Gulf sturgeon are native to the Gulf of Mexico, from Florida to Louisiana.
Gulf sturgeon were listed as a threatened species on October 30, 1991, pursuant to the Endangered Species Act of 1973. Gulf sturgeon have been covered under Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) since April 1, 1998. Appendix II includes species that may become threatened with extinction if their trade is not regulated and monitored.
The gulf sturgeon is an ancient fish first appearing in the fossil record 225 million years ago and evolving to its current form around the same time as sharks. They have a cartilaginous backbone and external scutes, which cover their head and the top part of their body. In addition, they have an asymmetrical caudal (tail) fin with the top half being larger than the bottom half. The head of the gulf sturgeon consists of a long snout preceded by four sensitive tactile barbels (fleshy protuberances similar in function to cat's whiskers) which sense prey.
The gulf sturgeon is anadromous and spends the major part of the year in freshwater, migrating to saltwater in the fall. Gulf sturgeon return to their natal stream to spawn. The best river habitat for gulf sturgeon are long, spring-fed free-flowing rivers. Steep banks and a hard bottom with an average water temperature of 60 to 72 degrees Fahrenheit are also characteristic of rivers where sturgeon inhabit. Sturgeon occupy the river bottom downstream of springs where they seek thermal refuge during hot summer days. Movement from the gulf and up-river movement generally occurs between February and April, while down-river movement occurs between September and November.
Sturgeon can live to be over 40 years old. Some sturgeon species can reach 10 to 12 feet in length and weigh over 1,200 pounds; however, the gulf sturgeon averages five to six feet in length. Sexual maturity of the female gulf sturgeon range from eight to seventeen years; whereas, male gulf sturgeon mature between seven and twelve years of age.
Adult sturgeon primarily feed during the winter months in marine or brackish water; however, adult sturgeon eat very little during their time in freshwater rivers. The gulf sturgeon diet consists of benthic-dwelling organisms such as isopods, amphipods, mollusks, crabs, grass shrimp, marine worms, and insect larvae. The gulf sturgeon's mouth is tubelike and toothless. It operates like a vacuum and can suck shrimp and polychaete worms from their burrows.