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6.1 Umatilla Dace: Rhinichthys umatilla
(Gilbert and Evermann)
Family: Cyprinidae -
Minnows or Carps
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Status
Global Rank: G4
Provincial Rank: S2
COSEWIC:
Vulnerable
Provincial Listing: Red |
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Distinguishing
Features
The
Scientific name of R. umatilla is derived from either the town of
Umatilla, Washington, the Umatilla River, or possibly Indian bands that live
in the area. Only in recent years has the Umatilla Dace R. umatilla
been verified as a species distinct from the similar looking Leopard Dace
R. falcatus. They average 7 to 10 cm in size and are creamy in colour,
somewhat darker on the back, with many large irregularly shaped spots.
Umatilla Dace of the Columbia River are less spotted than other populations of
R. umatilla and R. falcatus. The largest Umatilla Dace are
females.
Distribution
Columbia Basin: Within the
Columbia Basin, Umatilla Dace are found in the lower Columbia River, the
Kootenay river and the Slocan River.
British Columbia: In
addition to those locations in the Columbia Basin, the only known populations
in Canada of Umatilla Dace are in the Kettle and Similkameen
Rivers.
North America: Umatilla Dace
are known from the large main rivers of the lower Columbia Basin of
Washington, Oregon, Idaho, and British Columbia including: Columbia River at
Umatilla, Oregon; Payette River Idaho; Salmon River Idaho; Columbia river at
Rock Island Dam; and in the Columbia River east of the Cascade
Mountains.
Habitat
Umatilla Dace prefer rivers
with a cobble or stone bottom and relatively warm, productive waters. Yearling
dace are commonly found in shallow cobble habitat near current. Current flow
has been found to represent an obvious, but major influence on Umatilla Dace
habitat with the dace seeking faster currents than Leopard Dace. The dace use
very different habitat as a nursery area in contrast to adult habitat. The
shallow nursery zone is warmed by the sun in the summer which likely adds to
the productivity and metabolic activity of young dace in these
habitats.
Threats
Umatilla Dace is likely to
be endangered in Canada due to an extremely small population size, extremely
restricted distribution and presumed habitat preference. Much of the original
habitats of the Umatilla Dace on the Columbia River are now dammed. The
presence of rare fish in the Columbia Basin means that special care must be
taken when planning land use, including the building of any dams, around or on
local waters, especially those of the Columbia and its tributaries. Currently,
Umatilla Dace faces presumed threat of hydro dams in the Columbia River
although the effects of dams are unknown (Cannings and Ptolemy,
1998).
Biology
A large female Umatilla Dace
(119 mm) can have up to 3,200 eggs or more. Little information is known
otherwise about female reproduction. Beyond observations of Umatilla Dace
seeking refuge under rocks, no information is available on their behaviour
since they have not been observed in open water. Stomach contents saved from
collected specimens appear to contain mostly insect remains. They have not
been identified completely but algae are not seen as a major factor in the
food habits of the species compared to Speckled Dace. Predation and
competition by sympatric Cottus asper, C. rhotheus or Salmo
gairdneri may affect Umatilla Dace's abundance, although hiding under
rocks could provide dace with protection from predation.
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