tured in 1991 by poachers in the Congaree River, southern and northern shortnose sturgeon, but suf-
headwaters of the Santee River, M. Collins person- ficient data are not available for conclusions. Short-
al communication). Also, the presence of migrating nose sturgeon located upstream of Holyoke Dam at
ripe adults in the tidal reaches of both rivers (D. river km 140 of the Connecticut River have the
Cooke personal communication) and adults in slowest growth rate of any surveyed (Taubert
headwaters above dams is strong evidence that 1980a). This suggests growth advantages are associ-
adults in these populations are amphidromous, like ated with foraging in the lower river or fresh/water
those in north-central rivers. It seems likely that be- water interface.
fore the rivers were dammed, adults moved from Length at maturity (45-55 cm FL) is similar
fresh/saltwater foraging areas to discrete headwa- throughout the latitudinal range of shortnose stur-
ter reaches unknown to biologists. This could be geon, but southern fish mature at younger ages than
done by spawned fish, which would be far upriver do northern fish (Dadswell et al. 1984). Males ma-
after spawning. This situation may also occur un- ture at 2-3 years in Georgia, 3-5 years in South Car-
detected in other southern rivers. The extent of olina, and 10-11 years in the Saint John River; fe-
fresh water use in all southern rivers needs further males mature at 4-5 years in Georgia, 7-10 years in
examination. the Hudson River, and 12-18 years in the Saint John
The latitudinal pattern of saltwater use may re- River. Northern adults live 30-67 years; southern
flect bioenergetic adaptations for obtaining theop- adults live 10-25 years. These data are based on
timal environment for foraging and growth. Impor- studies that used pectoral rays toagefish, a proce-
tant components of shortnose sturgeon bioenerget- dure that is not verified with fish of known age.
ics are likely the spatio-temporal pattern of forage
abundance in river and estuarine areas and the
for foraging in fresh water. An acceptable thermal
regime in fresh water is shortest in northern rivers.
longest in north-central rivers where fish spend the
most time in fresh water, and may be intermediate
in southern rivers. Southern rivers have a suitable
thermal regime in fresh water during the fall, win-
ter, and spring, but available data indicate most fish
do not enter fresh water to forage; instead; they use
the fresh/saltwater interface. If so, perhaps forage
abundance in southern rivers is higher in the fresh/
saltwater interface than in fresh water.length of time a suitable thermal regime is available SpawningSpawning periodicity of males and females is poorly
understood. Males spawn more frequently than fe-
males in all northern populations, but perhaps not
in all southern populations. Dadswell (1979) esti-
mated that the Saint John River males spawned at
2 - year intervals and females at 3 to 5-year intervals.
Annual spawning by some males is documented in
the Merrimack, Connecticut, and Hudson rivers
(Dovel et al. 1992, Kieffer & Kynard 1996, M. Kieff-
er & B. Kynard unpublished data). Collins & Smith
(1996) indicate that some Savannah River fish of
both sexes spawn during successive years. Abun-
dance of spawning females can vary annually by an
order of magnitude in both northern and southern
rivers (Buckley & Kynard^2. Smith et al^11 ). More-
over, fecundity is highly variable among popula-
tions. Fecundity of females from the Saint John Riv-
er ranged from 27 000 to 208 000 eggs (average,Life historyGrowthDadswell et al. (1984) reviewed growth throughout
the latitudinal range. Growth of juvenile fish in all
populations is rapid, with growth of 14-30 cm during
the first year. Southern fish grow the fastest, butdo
not reach the larger size of northern fish. which con-
tinue to grow throughout life. This phenomenon
may be related to different bioenergetic styles of(^11) Smith,T.1.J., E. Kennedy & M.R. Collins. 1992. ldentification
Carolina. South Carolina Wildl. & Mar. Resour. Dept., Report
to US. Fish & Wildl. Serv. Proj. AFS-17 105 pp.
of critical habitat requirements of shortnose sturgeon in South