Montana's Fish Species of Special Concern
N. Redbelly Dace x Finescale Dace Hybrid
Status
of Northern Red Belly Dace x Finescale Dace Hybrid in Montana
(Phoxinus
eos x P. neogaeus)
Anne
Tews
Montana
Fish, Wildlife and Parks
P.O.
Box 938
Lewistown,
MT 59457
September 2001
Status
The
northern redbelly dace x finescale dace hybrid (Phoxinus eos x P. neogaeus) is a Montana species of special concern,
Class C (Hunter 1997). It was
placed on the species of concern list due to its rarity and unusual form of
genetic reproduction (Holton and Johnson 1996). Montana appears to be the only
state that designates special status for this hybrid fish.
However, South Dakota, North Dakota and Nebraska have granted special
status to the finescale (P. neogaeus) and northern redbelly dace (P. eos).
Distribution/Population/Taxonomy
Northern
redbelly dace are widely distributed in the north half of North America, from
the Rocky Mountain front to the East Coast, with isolated populations in
Manitoba and Saskatchewan (Scott and Crossman 1973). In Montana, northern
redbelly dace are fairly widespread east of the continental divide.
Finescale dace have a similar range but distribution in the United States
west of Minnesota is limited to glacial relict populations (Scott and Crossman
1973; Hubbs and Lagler 1970). Hybrids
of the two species are found throughout New England west to Nebraska, Colorado
and Montana and into Alberta (Dawley et al. 1987).
There are no official records of finescale dace in the state (Holton and
Johnson 1996). The finescale dace
has been found in the Milk River drainage in the Cypress Hills, just over the
Canadian border (Scott and Crossman 1973).
In
Montana, research and surveys for the hybrid dace have been limited.
The hybrid has been identified from about 13 waters (Figure 1) compared
with 49 occurrences of northern redbelly dace (Figure 2).
The University of Montana genetics lab did electrophoresis analysis of
twenty samples of Phoxinus spp. from
the Pine Butte Fen, near Choteau. Two
of the samples were from hybrid fish, and the rest were northern redbelly dace (Allendorf
1991b). The hybrid dace has
recently been identified from Siparyann Creek on the Charles M. Russell Refuge,
(Bramblett and Zale 2000).
Figure 1. Distribution of northern redbelly x finescale dace hybrid (MRIS, January 19, 2001 modified with added sites from Bramblett and Zale 2000 and Allendorf 1991b).
Figure 2. Northern redbelly dace distribution in Montana (MRIS, January 19, 2001).
There
is no easy field technique to differentiate the dace hybrid from the northern
redbelly dace (Holton and Johnson 1996). According
to William Gould (Emeritus Professor of Fisheries, Montana State University) the
hybrid dace can be differentiated from the northern redbelly dace by pharyngeal
teeth counts. Northern redbelly dace have pharyngeal tooth counts of 0,5 –5,0
and finescale dace has counts of 2,5 – 4,2. Hybrid Phoxinus
spp. have intermediate counts such as 1,5-5,1 or 1,5-4,1 or 1,5-4,0.
New (1962) gives a detailed description of morphometric differences
between the species.
Genetics/Life History/Ecology
Two
years of experiments on New England populations indicate that the hybrid dace
utilize a unique reproductive strategy called gynogenesis (Dawley et al. 1987).
The hybrid dace are female clones with identical eggs.
In gynogenesis, sperm from the male of a sexually reproducing related
species is needed to stimulate egg development, even though the genetic material
is not incorporated into the offspring. Entire populations can have the same
genes. In Minnesota several populations in the same vicinity are genetically
identical (Schlosser et al.1998). In
Montana, preliminary studies indicate that at least two genetically distinct
clones occur in the Pine Butte Fen (Allendorf 1991a).
Studies by Goddard et al. (1998) have shown that some female hybrid dace
clones reproduce by cloning while other individuals make haploid eggs that can
be fertilized by northern redbelly dace to produce diploid northern redbelly
dace offspring.
Northern
redbelly dace prefer quiet waters from beaver ponds, bogs and clear streams
(Scott and Crossman 1973, Holton and Johnson 1996). The finescale dace likes
similar habitat but is also found in larger lakes.
Phoxinus spp. spawn in the
spring and early summer (Scott and Crossman 1973). Schlosser et al. (1998) studied responses to environmental
stresses on the hybrid, finescale and northern redbelly dace.
He found that the hybrid had a greater physiological tolerance and
survived longer in oxygen stressed environments than the other two species.
Management
Further
inventory is needed to better define Phoxinus
spp. distribution in Montana. Due to difficulties of field differentiation
it is likely that some waters thought to contain only northern redbelly dace may
also have the hybrid. Phoxinus
spp. are not extremely common in Montana. Dr. Robert Bramblett (personal
communications) has conducted surveys on 43 prairie streams of the Missouri and
Yellowstone Rivers and identified Phoxinus
spp. at just three sites, one of which contained the hybrid. Few prairie streams in Montana have the clear pool-type
habitat preferred by Phoxinus spp.
Due to the limited distribution and knowledge of this species it is
important to reduce impacts to their known habitat, such as is described for Big
Coulee Creek Montana (Palmer 1994).
Changing
the status of the hybrid from a Class C to S2 should be considered based on the
Natural Heritage Program’s ranking system. An S2 ranking is warranted since
less than 20 different populations have been identified in the state and because
little is known concerning its distribution and biology.
Northern redbelly dace should be further evaluated as a special status
species. With only about 50
occurrences identified in the Montana River Information System and limited
knowledge about its biology an S3 ranking may be appropriate.
The special status of this species from surrounding states also serves as
a warning that special designation in Montana may be needed.
References
Allendorf, F.W. 1991a. All female species of fish at Pine Butte Preserve. University of Montana, Missoula.
Allendorf, F.W. 1991b. Letter to David Carr, Pine Butte Swamp Preserve. University of Montana, September 6, 1991.
Bramblett, R. G. and A.V. Zale. 2000. The ichthofauna of small streams on the Charles M. Russell National Wildlife Refuge, Montana. Intermountain Journal of Sciences 6:57-67.
Bramblett, R.G. 2001. Montana Cooperative Fishery Research Unit. Department of Ecology. Montana State University.
Dawley, R. M, R.J. Schultz and K. A. Goddard. 1987. Clonal reproduction and polypoidy in unisexual hybrids of Phoxinus eos and Phoxinus neogaeus. Copeia1987: 275 – 283.
Goddard, K.A., O. Megwinoff, L.L. Wessner, and F. Giaimo. 1998. Confirmation of gynogenesis in Phoxinus eos-neogaeus. The Journal of Heredity. 89(2)151-158.
Gould, W. R. 2001. Emeritus Professor of Fisheries, Montana State University. Letter dated March 12, 2001.
Holton, G.D. and H.E. Johnson. 1996. A field guide to Montana Fishes. Second edition. Dave Books editor. Montana, Fish, Wildlife and Parks, Helena, Montana.
Hunter, C. 1997. Fishes of special concern: an update. Montana Outdoor, November/December: 26 –27.
Hubbs, C.L. and K.F. Lagler. 1970. Fishes of the Great Lakes Region. University of Michigan Press.
MRIS. 2000. Montana River Information System web site. January 19, 2001.
New, J.G. 1962. Hybridization between two cyprinids, Chrosomus eos and Chrosomus neogaeus. Copiea.1:147-152.
Palmer, T. 1994. The Wonder Minnow. Montana Outdoors. July/August;42-43.
Schlosser, I.J., M.R. Doeringsfield, J.F. Elder and L. F. Arqayus. 1998. Niche relationships of clonal and sexual fish in a heterogeneous landscape. Ecology: 79: 953-968).
Scott W. B. and E.J. Crossman. 1973. Pages 392 –393 In: Freshwater fishes of Canada. Bulletin Fisheries Research Board of Canada. No. 184.
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