The pygmy whitefish (''Prosopium coulterii'') is a

freshwater whitefish The freshwater whitefish are fishes of the subfamily Coregoninae, which contains whitefishes (both freshwater and anadromous) and ciscoes, and is one of three subfamilies in the salmon family Salmonidae. Apart from the subfamily Coregoninae, th ...

of the genus ''

Prosopium ''Prosopium'' is a genus of freshwater whitefishes found in North America and parts of eastern Russia. It contains three fairly widespread species: the round whitefish, the pygmy whitefish, and the mountain whitefish. The remaining species, the B ...

'' in the family

Salmonidae Salmonidae is a family of ray-finned fish that constitutes the only currently extant family in the order Salmoniformes . It includes salmon (both Atlantic and Pacific species), trout (both ocean-going and landlocked), chars, freshwater whitefis ...

. Found in the mountain streams and lakes in western North America, it also has isolated populations in

Lake Superior Lake Superior in central North America is the largest freshwater lake in the world by surface areaThe Caspian Sea is the largest lake, but is saline, not freshwater. and the third-largest by volume, holding 10% of the world's surface fresh wa ...

and in

Ekityki Lake The Ekityki Lake (russian: Озеро Экитыки; ''Ozero Ekityki'') is a lake in the Chukotka Mountains, in the Siberian Far East. It belongs to the Ekityki river basin and the Ekityki River flows through it. Geography The shape of the Ekity ...

Chukchi Peninsula The Chukchi Peninsula (also Chukotka Peninsula or Chukotski Peninsula; russian: Чуко́тский полуо́стров, ''Chukotskiy poluostrov'', short form russian: Чуко́тка, ''Chukotka''), at about 66° N 172° W, is the eastern ...

Description

The pygmy whitefish is a small herring-like fish with a long and cylindrical body by comparison to other whitefishes. Silvery in colour, it has a brownish back, and a whitish belly.Becker, 1983, pp. 369–371 Black spots on the side called "parr marks", which are present on young

trout Trout are species of freshwater fish belonging to the genera '' Oncorhynchus'', '' Salmo'' and '' Salvelinus'', all of the subfamily Salmoninae of the family Salmonidae. The word ''trout'' is also used as part of the name of some non-salm ...

or "parrs", are present on the young of this species, and on adults in some Alaskan populations. Commonly ranging from in length, it is typically long, and reaches a maximum length of .Froese and Pauly, 2010 It is identified by its small size, and its large eye, which has a greater length than its blunt snout.Page and Burr, 1991, pp. 45–46 Its

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through c ...

and

pectoral fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

are usually clear, and its tail is clear with a faint dark spot. Its anal fin and pelvic fin are plain whitish. It has large scales with only 56–70 on its lateral line, fewer gill rakers, all characteristics that indicate a degree of differentiation from the other ''

'' fishes. Because of this, it is considered an early offshoot ( basal) species in its genus, and it is the most trout-like member of a genus considered the most trout-like and primitive whitefish group.

Taxonomy

The pygmy whitefish was first described by Carl H. Eigenmann and

Rosa Smith Eigenmann Rosa Smith Eigenmann (October 7, 1858 – January 12, 1947) was an American ichthyologist (the branch of zoology devoted to the study of fish), as well as a writer, editor, former curator at the California Academy of Sciences, and the first libra ...

in 1892, as ''Coregonus coulteri''. they named the species after the prominent botanist

John Merle Coulter John Merle Coulter, Ph. D. (November 20, 1851 – December 23, 1928) was an American botanist and educator. In his career in education administration, Coulter is notable for serving as the president of Indiana University and Lake Forest College a ...

.Dickson, 2008, p. 40 Since its initial description as a ''

Coregonus ''Coregonus'' is a diverse genus of fish in the salmon family ( Salmonidae). The ''Coregonus'' species are known as whitefishes. The genus contains at least 68 described extant taxa, but the true number of species is a matter of debate. The typ ...

'', it has been placed in the genus ''

'' of more primitive whitefishes. The members of this genus are distinguished from the other whitefishes by several characteristics, such as a single flap of skin over the nostril, rather than one; "parr marks" as on trout and char; a round body; and a small toothless mouth.Behnke, 2002, p. 335 The genus name ''Prosopium'', meaning "mask" in

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

, refers to the large bones in front of its eyes.

Distribution

The pygmy whitefish is found mostly in the northern

Rocky Mountains The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in straight-line distance from the northernmost part of western Canada, to New Mexico ...

, with three other disjunct populations. One is in

, another is in southwestern Alaska, and the third is in the

, Russia. The pygmy whitefish's range probably was continuous until the late

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...

. In the Rocky Mountains it is found in cold and rapid streams, and in cool lakes at depths of over . In Lake Superior it is found in cooler water, at depths of .

Ecology

In Lake Superior, the pygmy whitefish spawns during November and December at depths of . Females lay an average of 362 orange eggs, with a diameter of . Elsewhere, the pygmy whitefish migrates upstream to spawn, usually spawning in November or December in gravelly streams.Alaska Natural Heritage Program, 2005 Pygmy whitefish feed primarily on the aquatic

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

e of

insects Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of j ...

, and

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can ...

s. In Lake Superior, the amphipod '' Pontoporeia'' and various other crustaceans, mostly

ostracod Ostracods, or ostracodes, are a class of the Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 70,000 species (only 13,000 of which are extant) have been identified, grouped into several orders. They are small crustaceans, typi ...

s, form 77 percent of the pygmy whitefish's diet. The

burbot The burbot (''Lota lota'') is the only gadiform (cod-like) freshwater fish. It is also known as bubbot, mariah, loche, cusk, freshwater cod, freshwater ling, freshwater cusk, the lawyer, coney-fish, lingcod, and eelpout. The species is closel ...

kingfisher Kingfishers are a family, the Alcedinidae, of small to medium-sized, brightly colored birds in the order Coraciiformes. They have a cosmopolitan distribution, with most species found in the tropical regions of Africa, Asia, and Oceania, ...

s, and

tern Terns are seabirds in the family Laridae that have a worldwide distribution and are normally found near the sea, rivers, or wetlands. Terns are treated as a subgroup of the family Laridae which includes gulls and skimmers and consists of e ...

s, and pikes have been recorded preying on the pygmy whitefish.

References

Literature cited

* Alaska Natural Heritage Program (2005)
"Pygmy Whitefish"
''Fishes Tracking List and Status Reports''. Retrieved 10 February 2010. * Behnke, Robert J. (2002). ''Trout and Salmon of North America''. Free Press. . * Becker, George C. (1983).
Fishes of Wisconsin
' Madison, Wisconsin: University of Wisconsin Press. * Dickson, Tom (2008). ''The Great Minnesota Fish Book'' Minneapolis: University of Minnesota Press. * * Hubbs, Carl C.; Lagler, Karl F.; and Smith, Gerald R. (2004). ''Fishes of the Great Lakes Region'' revised ed. Ann Arbor: University of Michigan Press. * Mackay, W. C. (2000)
"Status of the Pygmy Whitefish (''Prosopium coulteri'') in Alberta."
''Wildlife Status Report'' 27 Edmonton, Alberta: Alberta Environment, Fisheries and Wildlife Management Division, and Alberta Conservation Association. Retrieved 16 February 2010 * Page, Lawrence M., and Burr, Brooks M. (1991). ''A Field Guide to Freshwater Fishes'' Boston: Houghton Mifflin. {{Taxonbar, from=Q2380754

Pygmy whitefish The pygmy whitefish (''Prosopium coulterii'') is a freshwater whitefish of the genus ''Prosopium'' in the family Salmonidae. Found in the mountain streams and lakes in western North America, it also has isolated populations in Lake Superior and i ...

Freshwater fish of the United States Fish of the Western United States Fish of the Eastern United States Fish of the Great Lakes Freshwater fish of Asia