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, ...

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 (biology), family of ray-finned fish, the only extant member of the suborder Salmonoidei, consisting of 11 extant genera and over 200 species collectively known as "salmonids" or "salmonoids". The family includes salmo ...

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

Lake Superior Lake Superior is the largest freshwater lake in the world by surface areaThe Caspian Sea is the largest lake, but is saline, not freshwater. Lake Michigan–Huron has a larger combined surface area than Superior, but is normally considered tw ...

and in Ekityki Lake,

Chukchi Peninsula The Chukchi Peninsula (also Chukotka Peninsula or Chukotski Peninsula; , ''Chukotskiy poluostrov'', short form , ''Chukotka''), at about 66° N 172° W, is the easternmost peninsula of Asia. Its eastern end is at Cape Dezhnev near the village ...

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 (: trout) is a generic common name for numerous species of carnivorous freshwater ray-finned fishes belonging to the genera '' Oncorhynchus'', ''Salmo'' and ''Salvelinus'', all of which are members of the subfamily Salmoninae in the ...

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 on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

and

pectoral fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish aquatic locomotion, swim. Apart from the tail or caudal fin, fish fins have no direct connection with the vertebral column ...

are usually clear, and its tail is clear with a faint dark spot. Its

anal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...

and

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hi ...

are plain whitish. It has large scales with only 56–70 on its

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelia ...

, 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 Carl Henry Eigenmann (March 9, 1863 – April 24, 1927) was a German-American ichthyology, ichthyologist of the late nineteenth and early twentieth centuries, who, along with his wife Rosa Smith Eigenmann, and his zoology students is credited wit ...

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 ...

.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 type ...

'', 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: 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 of all kno ...

, 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 great-circle distance, straight-line distance from the northernmost part of Western Can ...

, with three other disjunct populations. One is in

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

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

Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

. 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 (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e of

insects Insects (from Latin ') are 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 jointed ...

, and

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

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

ostracod Ostracods, or ostracodes, are a Class (biology), class of the crustacean, Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 33,000 species (only 13,000 of which are extant taxon, extant) have been identified,Brandão, S.N.; Antoni ...

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

burbot The burbot (''Lota lota''), also known as bubbot, mariah, loche, cusk, freshwater cod, freshwater ling, freshwater cusk, the lawyer, coney-fish, lingcod, or eelpout, is a species of coldwater ray-finned fish native to the subarctic regions of ...

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

s, and

tern Terns are seabirds in the family Laridae, subfamily Sterninae, that have a worldwide distribution and are normally found near the sea, rivers, or wetlands. Terns are treated in eleven genera in a subgroup of the family Laridae, which also ...

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. {{Authority control Pygmy whitefish 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 Pygmy whitefish