fromlarva to juvenilesappears tooccur atabout 30
mm T L (Table 1 )based onHudsonRiver specimens
(Bath et al.1981).
JuvenilemarineintervalAfter 2 to 6years of residence in theHudsonRiver,
juvenileAtlantic sturgeonmigrate tomarine wa-
ters. Dovel & Berggren(1983)reported thatsome
males leave the river inyear 2,whilefemales may
stay in the riveruntilyear 5 or 6.This migration to
marinewatersmarks amajorchange inecology, be-
havior, andgrowth for Atlantic sturgeon.Table l
showsapproximateages andsizes forearly (river-
ine)juveniles,late(sea migrant) juveniles, and in-
termediatejuveniles because thelaterincludes the
groupthatgradually emigratesfrom theriver dur-
ing a period ofrapid growth.After about 10years at
sea,juvenilesturgeonreachadultsize(about 150
cm TL, Table 1 for sexespooled).
Little isknownaboutAtlantic sturgeon in marine
waters exceptthatlarge juveniles areoften cap-
tured in LongIslandSound and off theLong Island
and New Jersey coasts in commercialfishinggear.
Reviews ofAtlantic sturgeonlifehistory(e.g., Van
Den Avyle^7 ) and informationspecific to the Hud-
son Riverestuary(Dovel & Berggren1983,C.L.
Smith1985)describe post-emmigrationjuveniles as
inhabitants of marinewaters.However,largejuve-
niles(50–150 cm T L ) mayreside in riverine habitats
along theAtlanticcoast duringwarmmonths. At-
lanticsturgeonsampling in theHudsonRiver has
documented the occurrence of large juveniles
(sometimescalled pre-adults; Dovel & Berggren
1983, VanEenennaam et al.1996).Data ofDovel &
Berggren(1983) on tagrecapturesshowthat most
fishwerereportedfromrivermouths and thelower
sections of coastalriversfromCape Cod toChesa-
peakeBay.Murawski &Pacheco^8 described asimi-
lar pattern fortagging andrecaptures in the St.
LawrenceRiver, Quebec.LatejuvenileAtlantic
sturgeon oftenenter andreside inriversthatlack
activespawning sites(e.g.MerrimackRiver, Mas-
sachusetts:Kieffer &Kynard1993).MostAtlantic
sturgeon inrivers of thecentral US Atlanticcoast
are probablyfrom theHudsonRiver populationJuvenile riverineinterval
The juvenileperiod of the Atlantic sturgeonlife cy-
cle is marked by majorecologicalchanges, and it
can be dividedinto twolifehistory intervals: early
and latejuvenile (Figure 3). The precisedivision be-
tween theseintervals is unclear because changes
are gradual, althoughgrowth isveryrapid (Figure
4). Consequently, Iadded athird intermediate in-
terval for age and growthstatisticsshown in Table 1.
The firstjuvenile interval is limited to riverine hab-
itats. Relativelygoodinformation isavailable for
this interval due toresearch in theHudsonRiver
estuary.
JuvenileAtlantic sturgeon arewelldistributed
overmuch of theHudsonRiverfromJulythrough
September, andthey usedeepchannel habitats as in
otherlifeintervals (Figure 3). The largestnumbers
ofjuvenilesappear to belocatedfrom km 63 to 140
(Dovel & Berggren1983). Aswatertemperature
dropsbelow 20° C in the fall,juvenilesform an
overwintering distribution in brackish water be-
tween km 19 to 74 (Dovel & Berggren1983).From
October through June,this region of theHudson
Rivercontainsmanyjuveniles andtheyappear to
move littleduring the period.Upstreamdispersion
ofjuvenilesbegins inlatespring.Somejuvenile At-
lanticsturgeonhavebeen recorded in theoverwin-
teringareaused by pre-spawning,adult shortnose
sturgeon (EsopusMeadows, km134) asearly as
mid-Aprilwhichindicatessomevariation in the
generalmigrationpattern.
JuvenileAtlantic sturgeongrowquickly in the
firstthreeyears oflife (70 cm TL at age 3,Figure 3)
but growthslowsconsiderably if theyremain in the
HudsonRiver estuary (Dovel &Berggren1983).
Riverinejuvenilesfeed on aquaticinsects, amphi-
pods,isopods, and smallmolluscs(Scott &Cross-
man 1973). (^8) Murawski, S A. &A.L.Pacheco.1977.Biological andfisheries
data onAtlantic sturgeon,Acipenseroxyrhynchus(Mitchell).
National MarineFisheriesService TechnicalSeries 10,High-
lands. 69 pp.