Environmental Biology of Fishes 48:418–419, 1997.
© 1997 KluwerAcademicPublishers.Printed in theNetherlands
Threatened fishes of the world:Scaphirynchus suttkusiWilliams&
Clemmer, 1991 (Acipenseridae)
Richard L.Mayden &Bernard R.Kuhajda
Department of Biological Sciences, Box 870344, University of Alabama Tuscaloosa, AL 35487–0344, U.S.A.
Common names: Alabama shovelnose sturgeon, Alabama stur-
geon(E).
Conservationstatus:Recommended for protection (Ramsey
1976, 1986).Proposed asFederallyEndangered 15June 1993
(FederalRegister1993);listingpostponed 21 June 1994 (Federal
Register1994a),listingwithdrawn 15December 1994 (Federal
Register 1994b). Currently receives no protection.
Identification:One of threespecies ofScaphirynchusdistinguished byhavingorangish-yellow,brassy-orange, tobrownish-tanhead,
body, and fincoloration inmatureadultssignificantlylargerorbit diameter; no sharp, retrosespiness on snout tip andanterodorsal to
eye;and poorly developed squamation on venter. Other features include significantly different number of dorsal plates. anus to anal fin
plates.plates posterior toanal fin. lateral platesanterior todorsal finorigin.dorsal finrays, and 11 head,fin, and bodyproportions,relative
to its sister species S.platorynchus.Complete description by Williams & Clemmer (1991) and Mayden & Kuhajda (1996). Photograph by
John Caruso.
Distribution:Endemic to larger rivers of Mobile Basin. Former distribution included Tombigbec, Alabama,Canada, Coosa, Alabama
and Mississippi rivers. Recent collections are only from the Alabama River, Alabama below the lowermost two dams. Abundance:
Speciesvereyrare:only 36 specimensknownfrom museumrecords orphotodocumentation.Contrary todecisions by theU.S.Fish and
WildlifeService(FederalRegister1994b), the species is notextinct: twoadult specimenswerecaptured inthe AlabamaRiver in Spring
I995 and one inSpring1996. Allcurrentdata,extendingfrom thegeneraldegradation of theMobileBasinecosystem(U.S. Fish and
Wildlife Service 1994) tothe paucity ofrecords and specimens ofthe Alabamasturgeon.indicate that this is one of themostendangered
species in theUnitedStates. However,this has notalwaysbeen thecase. as thisspeciesoncemaintained a healthy populationsize, but has
declined in this century due to anthropogenic changes to the ecosystem. In a report to the U.S. Congress in 1898 (US. Commission of Fish
and Fisheries 1898) the total catch of ‘shovelnose sturgeon’ from rivers in alabama was 19 500 kg. Of this, captures of the shovelnose
sturgeon.S platorynchus, from the Tennessee River numbered only 500 kg, while captures of S. suttkusi from the Alabama and Black
Warrior (Tombigbee) rivers numbered 19 000 kg. Given that an Alabama sturgeon averages 1 kg, this represents a substantial harvest of a
speciesthat iscurrently extremelyrare.Habitatandecology:Life historyaspects ofS. suttkusiare poorlyknown.Appears toprefer
relativelystablesubstrates ofgravel andsand inareas ofcurrent inlarge river channels, butwillalso occurover softersediments. Its
Springdiet isdominated bymacroinvertebratesthattypically buryin sandysubstrates inbothriffle and lenticdepositional areas. Occa-
sionally, small fish plant items. and some mollusks and snails associated with relatively stable and silt-free substrates occur in stomachs.
Based onfood itemspresent in stomachs andlack ofitems(invertebratetaxa) indicative of certain habitats,Spring-collectedAlabama
sturgeon appear to feed in sandy depositional areas with very little silt and slow to moderate current (see Burke & Ramsey 1995, Mayden
& Kuhajda1996).Reproduction:Reproductivebiology notwellknown;most information is inferredfrom itsclosestrelative,S. plato-
rynchus.Spawning season probably extends from February to July. Species of Scaphirynchusspawn in freshwater and are known to
migrate upstream to spawning areas as ‘spawning runs’ that may be triggered by rising water levels in the Spring and early Summer.
Probablyspawns inlarger rivers inswiftcurrent andcoarse, rock orgravelsubstrates, but mayalso spawn overhard bottomsubstrates in
main-channelareas or intributaries tomajor rivers.Likeothermembers of thefamily,individuals ofthisspecies probably donot spawn
every year. Rather, following sexual maturity at five to seven years of age, spawning may occur every one to three years with a hiatus of
evengreaternumber ofyearspossible.Althoughunknown forthe Alabamasturgeon.eggs ofshovelnose sturgeon are adhesive and
require current for proper development, indicating that both a stable and silt-free, substrate is necessary for their successfull development.
Hatching occurs in five to eight days under proper conditions (see Mayden & Kuhajda 1996) Threats:Recruitment of Alabama sturgeon,
indicative of spawning success, has declined precipitously during this century. Because this species has not been sought in the 20th century
in acommercialfishery,this decline can becorrelateddirectlywith habitatdegradation,modifications of the rivers for navigational
purposes, mining operations in and adjacent to the rivers, and the construction of dams in the Mobile Basin, all of which have flourished in
this century. All of these changes result in increased siltation of benthic habitats, reduced overall current velocities, elimination of natural
seasonal flooding of river flood plains, irregular flow regimes within the river channels, the loss of and/or change in structure of reverine