prespawning Saint John River adults have a 2-step
migration and fish must likely move about 45-65 km
in spring (Dadswell 1979). The 2-step migration pat-
tern used by most Connecticut River adults that
need to move 80 km may be an energetic adaptation
to take advantage of warmer river temperature, re-
duced river discharge, and superior physiological
condition of fish in the fall compared to spring. Only
adults in southern rivers (Savannah, Altamaha, and
Pee Dee rivers) have a long 1-step migration that
exceeds 80 km.Mostsouthern fish migrate to about
river km 200 or farther in late winter (Marchette&
Smiley^8 , Hall et al. 1991, Rogers & Weber4,9).Al-
though details are lacking, both fall and spring mi-
grations were found in the Altamaha River (Rogers
&Weber 19954 ).This indicates a greater diversity of
migration patterns than found previously in south-
ern rivers. The presence of long 1-step winter migra-
tions that exceed 200 km in southern rivers may be
related to warmer river temperatures or the ability
of southern adults to continue feeding in winter, or
both. These conditions provide energy resources
for a long migration that are not available for north-
ern adults. Northern adults cease foraging in No-
vember, about 5 months before most fish initiate a
short 1-step spawning migration. Although some
adult shortnose sturgeon in a population migrate
upstream in fall and some migrate in spring, all
spawn together. The pre-spawning migrations of
winter and spring ‘races’ of European sturgeon spe-
cies (Berg 1959) likely also reflect different migra-
tion styles of adults that eventually spawn together.
Shortnose sturgeon spawn in late winter (south-
ern rivers) to mid-spring (northern rivers) when riv-
er temperature increases to about 9°C. Spawning
usually ceases at 12-15° C (Dadswell et al. 1984,
Buckley&Kynard 1985b, Hall et al. 1991, O’Herron
et al. 1993, Squiers et al.l4,Kieffer&Kynard 1996).
When high Connecticut River discharge delayed
spawning in 1994, a few females spawned success-
fully at 18°C(M. Kieffer &B. Kynard unpublished11568 eggsper kg body weight; Dadswell et al.
1984). Females in the Saint John River have the
highest mean potential lifetime fecundity, 197 000
eggs, compared to111 000eggs for Pee Dee River
females (Boreman et al.^12 ).Males dominate the sex
ratio of spawners (not the total population) in all
rivers. Sex ratios of male:female spawners in 2
northern and 1 southern river are for Hudson River
- 2.5:1 (Pekovitch^13 ); Connecticut River –3.5:1
(Taubert 1980b) and 3 to 7:1 (Buckley &Kynard
1985b, M. Kieffer&B. Kynard unpublished data);
and Savannah River –3.5:1 (Collins &Smith 1996).
Shortnose sturgeon vary in prespawning migra-
tion pattern and the type present may reflect ener-
getic adaptations to migration distance, river dis-
charge and temperature, and physiological condi-
tion of fish (Kieffer &Kynard 1993). The three pat-
terns of migrations are (1) a short 1-step migration
done in spring onlya few weeks before spawning,
(2) a long 1-step migration done many weeks inlate
winter and spring before spawning, and (3) a short
2 - step migration composed of a long fall migration,
which places fish near the spawning site for over-
wintering, then a short migration like the short 1 -
step in spring to spawn. Amphidromous adults in
the Merrimack, Connecticut, and Delaware rivers
that overwinter only a short distance (< 25 km)
downstream of the spawning area use a short 1-step
migration (Buckley&Kynard 1985a, Kieffer&Ky-
nard 1993,O’Herronet al. 1993, M. Kieffer&B. Ky-
nard unpublished data). Of the Connecticut River
prespawning adults that in the fall prior to spawning
need to move a total of 80 km or more to spawn,
70% use a 2-step migration and30%use a long 1 -
step spring migration (Buckley &Kynard 1985a).
Nolong 1-step spring migration was found in Con-
necticut River prespawners that, as of their fall lo-
cation, had to move 140 km or farther to spawn.
Although total migration distance is unclear,
(^12) Boreman,J., W.J. Overholtz, & M.P. Sissenwine. 1984. A pre-
liminary analysis of the effects of fishing on shortnose sturgeon.
Nat. Mar. Fish. Serv., Woods Hole, Mass., Ref. Doc. No. 84-17.19
pp. 13
Pekovitch, A. W. 1979. Distribution and some life history as-
pects of the shortnose sturgeon (Acipenser brevirostrum) in the
upper Hudson River estuary. Report of Hazleton Environ. Sci.
Corp., III. 23 pp.
(^14) Squiers, T.S., M. Robillard & N. Gray. 1993. Assessment of po-
tential shortnose sturgeon spawning sites in the upper tidal reach
of the Androscoggin River. Report of Maine Dept. Mar. Re-
sour., Augusta, Maine. 43 pp.