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ALLOZYME VARIATION IN QONYTAIL
<br />(Hamman 1982, personal communication). The
<br />same technique was successfully used in 1983 and
<br />1984 spawning trials with 2- and 3-year-old,
<br />hatchery-reared fish at Dexter (Hamman 1985;
<br />see also Marsh 1985).
<br />We have not measured allozymic variability in
<br />F, bonytails; they were considered too valuable to
<br />kill. Therefore, we cannot be certain that F2 prog-
<br />eny produced by natural spawning resulted from
<br />gamete contribution by all available adults (ge-
<br />nomes); F, brood fish could be more variable than
<br />present data indicate. However, presumed spawn-
<br />ing or prespawning activity in Dexter ponds (mill-
<br />ing and chasing behavior, nudging between and
<br />among individuals) included more than 200 fish
<br />(Minckley, unpublished). The only other available
<br />information on bonytail spawning is that from Jo-
<br />nez and Sumner (1954) for Lake Mohave where
<br />an estimated 500 bonytails were observed broad-
<br />casting gametes over a gravelly shelf.
<br />Realistic management of any species must in-
<br />clude maintenance ofgenetic diversity (Meffe 1986;
<br />Meffe and Vrijenhoek 1988; Echelle, in press), and
<br />it is possible that the Dexter brood stock of bony-
<br />tails represents only part of the genetic variability
<br />of the species. In turn, reintroduction of bonytails
<br />with low genetic variability might well alter the
<br />genetic structure of a smaller wild population (Ka-
<br />puscinski and Philipp L988). There is no way to
<br />answer the question of genetic variability until
<br />atiother population of wild bonytails is discovered
<br />and compared with hatchery fish. Allozyme vari-
<br />ability in F2 fish from Dexter is nonetheless clearly
<br />comparable with average values recorded for oth-
<br />er western cyprinids and for most measures is not
<br />significantly different from that of a congener.
<br />There has been no evidence of unusual morpho-
<br />logic abnormalities in the Dexter stock or their
<br />progeny, they have reproduced naturally and suc-
<br />cessfully, albeit in hatchery ponds (Jensen, per-
<br />sonal communication), and hatchery-produced
<br />individuals have survived to adulthood when
<br />stocked in Lake Mohave. In light of these factors
<br />and the rarity of the species, we do not have major
<br />reservations about the continued use of the Dexter
<br />bonytail stock for reintroductions in the lower
<br />Colorado River basin. However, we strongly sup-
<br />port an ongoing effort to find other bonytail pop-
<br />ulationsand recommend expansion of the search.
<br />The Colorado River Fishes Recovery Team
<br />(USFWS, unpublished) already has called for the
<br />transfer of any bonytail encountered in nature to
<br />captivity as insurance against extinction and to
<br />further the overall recovery effort.
<br />Acknowledgments
<br />135
<br />Principal funding for this study was from the
<br />USFWS, Office of Endangered Species, Albuquer-
<br />que, New Mexico. J. E. Johnson, formerly of that
<br />office and now at the University of Arkansas, is
<br />commended for his continued support and pa-
<br />tience. The University of California-Los Angeles
<br />(UCLA), Department of Biology Fisheries Pro-
<br />gram, and grants from UCLA Biomedical Support
<br />and the UCLA Committee on Research (U.R.
<br />3674), and Arizona State University (ASU), pro-
<br />vided additional assistance. B. L. Jensen and R.
<br />L. Hamman, Dexter National Fish Hatchery, sup-
<br />plied fish and information; D. L. Swofford pro-
<br />vided the BIOSYS- I computer program. Work on
<br />the bonytail was conducted under USFWS permit
<br />PRT 6768 t 1 and with appropriate management
<br />and research permits from the states of Nevada
<br />and Arizona. The manuscript was reviewed and
<br />improved by M. E. Douglas and P. C. Marsh, ASU.
<br />References
<br />Avise, J. C. 1977. Genic heterozygosity and rate of
<br />speciation. Paleobiology 3:42232.
<br />Brewer, G. J. 1970. An introduction to isozyme tech-
<br />niques. Academic Press, New York.
<br />Buth, D. G. ! 982. Locus assignments for general mus-
<br />cle proteins of darters (Etheostomatini). Copeia
<br />1982:217-219.
<br />Buth, D. G. 1983. Duplicate isozyme loci in fishes:
<br />origins, distribution, phyletic consequences, and lo-
<br />cus nomenclature. Isozymes: Current Topics in Bi-
<br />ological and Medical Research 10:381-400.
<br />Buth, D. G. 1984. Allozymes of the cyprinid fishes:
<br />variation and application. Pages 561-590 in B. ].
<br />Turner, editor. Evolutionary genetics of fishes. Ple-
<br />num, New York.
<br />Crabtree, C_ B., and D. G. Buth. 1981. Gene dupli-
<br />cation and diploidization in tetraploid catostomid
<br />fishes Catostomus fumeivenrris and C. santaanae.
<br />Copeia 1981:705-704.
<br />Echelle, A. A. [n press. Conservation genetics and gen-
<br />ic diversity in threatened fishes of western North
<br />America. !n W. L. Minckley and J. E. Deacon, ed-
<br />itors. Battle against extinction: native fish manage-
<br />ment in the American West. University of Arizona
<br />Press, Tucson.
<br />Erick, L. 1983. An electrophoretic investigation of the
<br />cytosoiic di- and tripeptidases of fish: molecular
<br />weights, substrate specificities, and tissue and phy-
<br />logenetic distributions. Biochemical Genetics 21:
<br />309-322.
<br />Gilben, C H., and N. B. Scofield. 1898. Notes on a
<br />collection of fishes from the Colorado basin in Ar-
<br />izona. Proceedings of the U.S. National Museum
<br />20:487-499.
<br />Hamman, R. L. 198 I . Hybridization of three species
<br />ofchub in a hatchery. Progressive Fish-Culturist 43:
<br />140-141.
<br />
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