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NAS - Nonindigenous Aquatic Species |
Common Name: wakasagi
Identification: Moyle (1976a); Page and Burr (1991).
Size: 17 cm.
Native Range:
Japan (Page and Burr 1991).
Nonindigenous Occurrences: The wakasagi was stocked in California in Sly Park Reservoir (El Dorado County), Dodge Reservoir (Lassen County), Spaulding Reservoir (Nevada County), Big Bear Lake (San Bernardino County), Dwinnel Reservoir (Siskiyou County), Shastina Reservoir (Siskiyou County), and Freshwater Lagoon (Humboldt County) in 1959 (Wales 1962; Moyle 1976a; Courtenay et al. 1984; Dill and Cordone 1997). It was then stocked in Lake Almanor (Plumas County) on the North Fork Feather River in 1972 (Dill and Cordone 1997). It migrated downstream from Lake Almanor to Lake Oroville (Dill and Cordone 1997). It has recently been observed in the lower American River, Cache Slough off the Sacramento River and the Mokelumne River, and at the Central Valley Project and State Water Project fish salvage facilities in the south Delta (Dill and Cordone 1997). The species can be expected to occur in the lower Klamath, the Sacramento, and possibly other drainages (Moyle 1976a). Most recently, it was found in the Sacramento-San Joaquin Estuary, Suisun Marsh, and the the Yolo Bypass, Yolo and Solano Counties, (Aasen et al. 1998; Sommer et al. 2001; Matern et al. 2002; Moyle, unpublished).
Means of Introduction: Wakasagi were intentionally introduced in 1959 from Japan by the California Department of Fish and Game as an experimental forage fish for trout (Wales 1962; Moyle 1976b; Dill and Cordone 1997).
Status: This species is established in several reservoirs and associated tributaries in California (Moyle 1976a; Shapovalov et al. 1981; Courtenay et al. 1986). It has not been recorded in Big Bear Lake since 1960 (Swift et al. 1993).
Impact of Introduction: This species has been found to negatively impact kokanee Oncorhynchus nerka and threadfin shad D. petenense (Dill and Cordone 1997). It also is known to hybridize with the native and federally endangered delta smelt Hypomesus transpacificus. Hybridization between the two species was suspected by Courtenay et al. (1986), and was later confirmed (Dill and Cordone 1997; Trenham et al. 1998).
Remarks: Dill and Cordone (1997) reviewed its introduction history in California. In documenting the original introduction, Wales (1962) incorrectly identified the species as Hypomesus olidus. Several authors (e.g., Moyle 1976a; Lee et al. 1980 et seq.) treated the introduced wakasagi as a subspecies of H. transpacificus (i.e., as H. t. nipponensis). In California the wakasagi is generally considered a freshwater species, hence its often-used name "freshwater smelt" in that state; however, it has recently been discovered in brackish waters, further threatening the continued survival of the imperiled delta smelt (Dill and Cordone 1997).
Courtenay, W. R., Jr., D. A. Hensley, J. N. Taylor, and J. A. McCann. 1984. Distribution of exotic fishes in the continental United States. Pages 41-77 in W. R. Courtenay, Jr., and J. R. Stauffer, Jr., editors. Distribution, biology and management of exotic fishes. Johns Hopkins University Press, Baltimore, MD.
Courtenay, W. R., Jr., D. A. Hensley, J. N. Taylor, and J. A. McCann. 1986. Distribution of exotic fishes in North America. Pages 675-698 in C. H. Hocutt, and E. O. Wiley, editors. The zoogeography of North American freshwater fishes. John Wiley and Sons, New York, NY.
Lee, D. S., C. R. Gilbert, C. H. Hocutt, R. E. Jenkins, D. E. McAllister, and J. R. Stauffer, Jr. 1980 et seq. Atlas of North American freshwater fishes. North Carolina State Museum of Natural History, Raleigh, NC.
Moyle, P. - University of California, Davis.
Moyle, P. B. 1976a. Inland fishes of California. University of California Press, Berkeley, CA.
Page, L. M., and B. M. Burr. 1991. A field guide to freshwater fishes of North America north of Mexico. The Peterson Field Guide Series, volume 42. Houghton Mifflin Company, Boston, MA.
Shapovalov, L., A. J. Cordone, and W. A. Dill. 1981. A list of freshwater and anadromous fishes of California. California Fish and Game 67(1):4-38.
Sommer, T, B. Harrell, M. Nobriga, R. Brown, P. Moyle, W. Kimmerer, and L. Schemel. 2001.
Swift, C. C., T. R. Haglund, M. Ruiz, and R. N. Fisher. 1993. The status and distribution of the freshwater fishes of southern California. Bulletin of the Southern California Academy of Science 92(3):101-167.
Trenham, P.C., H.B. Shaffer, and P.B. Moyle. 1998. Biochemical identification and assessment of population subdivision in morphologically similar native and invading smelt species (Hypomesus) in the Sacramento-San Joaquin Estuary, California. Transactions American Fisheries Society 127:417-424.
Wales, J. H. 1962. Introduction of pond smelt from Japan to California. California Fish and Game 48(2):141-142.
Other Resources:
FishBase Fact Sheet
Author: Pam Fuller
Revision Date: 4/25/2006 Citation for this information:
Pam Fuller. 2009. Hypomesus nipponensis. USGS Nonindigenous Aquatic Species Database, Gainesville, FL.
<http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=794> Revision Date: 4/25/2006
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