potamadromous andthus, migratefrommarine or
lakewaters torivers tospawn (Bemis & Kynard
1997 this volume). However,almost nothing is
known of thedegree ofhomingfidelity shown by
acipenseriforms.Althoughhomingfidelity of fishes
may be studieddirectly bymeans ofcapture-mark-
recapture(e.g.,Melvin et al.1986), therelativescar-
city and highvalue ofsturgeons precludes such an
approach. An alternative is toassesshomingfidel-
ity indirectlythrough geneticanalysis (Tallman &
Healey1994).
Homing fidelity ofsturgeons through genetic
analyseswouldbest beassessedamongpopulations
in riversthat drain to acommonwaterbody and
thathistoricallyhave astable geographic history to
avoidconfoundment byfoundereffects as aconse-
quence ofrecolonizations. Stabile et al.(1996)used
bothRFLP andsequencinganalysis ofmtDNA to
estimate gene flow among five stocks of A. o. des-
otoithatoccur in eight drainagesthatfeed theGulf
of Mexicobetween Mississippi andFlorida. The
five stocksweredefinedbased onχ^2 analyses (p <
0.05) ofhaplotypefrequencies;somestockswere
equivalent tosinglepopulations, whereasothers
wereregional stocksmacle up to two ormore pop-
ulations. Pairwise gene flow estimates (Nm) be-
tween stockswerederivedfrom Fstvalues(Wright,
1943)obtained viaAMOVAanalysis(Excoffier et
al.1992).
Pairwiseestimates ofgeneflow (Table 1)among
the Gulfstocks based on sequencinganalysisrang-
ed from0.15between thewestern(LakePonchar-
Gene flow and homing ,fidelity train andPearlRiver) stock and theEscambia Riv-
er-YellowRiver stock, to 1.2 between theEscambia
Mostpopulations ofsturgeons are anadromous or River-YellowRiverstock and theeasternstockTable 1. Estmates of gene flow among populations of Acipenser oxyrinchus desotoi. Values above diagonal are based on data from
restriction fragmentlengthpolymorphismanalysis ofmitochondrial DNA(mtDNA):values belowdiagonal are based ondatafrom
sequenceanalysis of 203base pairs ofmtDNAcontrol region.stockanalysis,frequencies of genotypes must be
characterized inreferencespawning stocks and in
the mixedfishery.
A targetedcoastalfishery forA. o. oxyrinchus
has developed inrecentyears along the mid-Atlan-
tic coast of New Jersey and NewYork(NewYork
Bight) andbycatchfisheries havebeenreported off
the southeasterncoast of theU.S. (Collins et al.
1996). Waldman etal. (1966a)performedRFLP
analysis of specimens of A. o. oxyrinchus from eight
populationsfromCanada toGeorgia and conclud-
ed, based onhaplotypefrequency differences,that
threestatisticallydiscrete ( p <0.0001)stocksexist:
(1) Canadian, (2) HudsonRiver, and (3)southeast-
ern.Haplotypic frequencydata ofthesestockswere
thenused in amixture model(constrainedleast
squares; Xu etal., 1994) toestimate therelative con-
tributions ofeach ofthesestocks to a sample of At-
lanticsturgeon (N =112) from thefishery in the
New York Bight off New Jersey. This analysis
showed a 97% to 99%contribution from theHud-
son Riverstock.with theremainderfrom thesouth-
easternstock. The overwhelmingcontribution of
the HudsonRiverstock wasattributedboth to (1) a
hypothesized tendency formarinemigratingAtlan-
tic sturgeon to remainwithin thegeographic prov-
inces oftheir natalrivers(theHudson River iswith-
in the Virginianprovince), and (2) to the absence of
otherrobustAmericanAtlantic sturgeon popula-
tions within theVirginianprovince.
Western Pascago ula Escambia- Choctawhatchee Eastern
Yellow
Western – – 0.26 0.1 I 0.23
Pascagoula 249.75 – – – –
Escambia-Yellow 0.15 0.23 – 0.45 0.66
Choctawhatchee 0.22 0.35 0.79 – 0.09
Eastern 0.11 0.27 1.20 0.97 –