7863

• UCREFRP Catalog Number: 7863
• Author: Nature Conservancy, T.
• Title: Candidate Species Reports from the Natural Heritage Central Database.
• USFW Year: 1996.
• USFW - Doc Type: \
• Copyright Material: NO

.

GABUNDCOM:

GRANGE:
GRANGECOM:

GTREND:
GTRENDCOM:

GPROTEOS:
GPROTCOM:

~

Never seen in large numbers.

B
Historically recorded in 14 states of the Missouri and
Mississippi rivers and their larger tributaries; currently
known from Missouri, Montana, Nebraska, North Dakota, and
Wyoming (USFWS). ^Mainly in the Missouri River, Montana and
Wyoming to Illinois; also in the Mississippi River from
confluence with Missouri River to Ohio River, and also
(formerly) in southern Mississippi and Louisiana. Fairly
common in middle Missouri River, rare elsewhere (Page and
Burr 1991) .

B

A
See Federal Register (18 January 1995, p. 3614) for state
conservation classifications applicable in the mid-1990s.

A
Decline has resulted mainly from human-induced changes in
river conditions. Dams have flooded river habitat, altered
temperature and flow regimes, reduced sediment transport and
turbidity, fragmented populations, and reduced movement
opportunities. Channelization has reduced habitat diversity
and reduced overbank flooding. Pollution and water depletion
from industry and agriculture may have altered water
quality. Sand and gravel excavation have removed habitat and
restricted fish movements in some areas. Further water
depletion is likely to occur in the future due to energy
development in the Upper Missouri River Basin, increased
interbasin transfer of water, and increased municipal,
industrial, and irrigation use. Dredging for channel
maintenance and sand/gravel extraction will continue in new
areas. Severe drought in the early 1990s may have eliminated
populations in some Missouri River tributaries; populations
in the mainstem Missouri River may be too small and too
widespread to naturally recolonize these tributaries even if
suitable habitat is available. May be negatively impacted by
the numerous species of non-native fishes that have been
introduced into the habitat (Federal Register
60(11) :3613-3615, 18 January 1995).

GFRAGIL: A
GFRAGILCOM: Highly specialized for highly turbid waters.

GTHREAT:
GTHREATCOM:

GOTHCONSID:

Rank and Reasons:

G2 GREVDATE: 92-06-01
Historically occurred in the Missouri and Mississippi rivers
and their larger tributaries, now nearly restricted to the
middle Missouri River; large decline in range and abundance;
continuing threats from human-caused changes in river
conditions.

GRANK:
GREASONS:

Needs:
GRSRCHNEED: Mark and recapture studies to determine individual movement.