Pygmy whitefish

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Pygmy whitefish
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Salmoniformes
Family: Salmonidae
Genus: Prosopium
Species:
P. coulterii
Binomial name
Prosopium coulterii

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 in Ekityki Lake, Chukchi Peninsula.

Description

The pygmy whitefish is a small herring-like fish with a long and cylindrical body by comparison to other whitefishes.

anal fin and pelvic fin are plain whitish.[2] 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 Prosopium fishes.[1] Because of this, it is considered an early offshoot (basal) species in its genus,[1] and it is the most trout-like member of a genus considered the most trout-like and primitive whitefish group.[5]

Taxonomy

The pygmy whitefish was first described by Carl H. Eigenmann and Rosa Smith Eigenmann in 1892, as Coregonus coulteri. they named the species after the prominent botanist John Merle Coulter.[6] Since its initial description as a Coregonus, it has been placed in the genus Prosopium of more primitive whitefishes.[1] 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.[5] The genus name Prosopium, meaning "mask" in Greek, refers to the large bones in front of its eyes.[6]

Distribution

The pygmy whitefish is found mostly in the northern

Ekityki Lake, Chukchi Peninsula, Russia. The pygmy whitefish's range probably was continuous until the late Pleistocene.[7] In the Rocky Mountains it is found in cold and rapid streams, and in cool lakes at depths of over 6 metres (20 ft).[4] In Lake Superior it is found in cooler water,[1] at depths of 18 to 89 metres (59 to 292 ft).[4]

Ecology

In Lake Superior, the pygmy whitefish spawns during November and December at depths of 31 to 46 metres (102 to 151 ft). Females lay an average of 362 orange eggs, with a diameter of 2.57 millimetres (0.101 in).

insects, and crustaceans.[2] In Lake Superior, the amphipod Pontoporeia and various other crustaceans, mostly ostracods, form 77 percent of the pygmy whitefish's diet.[1] The burbot, kingfishers, and terns, and pikes have been recorded preying on the pygmy whitefish.[1][2]

References

  1. ^ a b c d e f g h i j k Becker, 1983, pp. 369–371
  2. ^ a b c d e Froese and Pauly, 2010
  3. ^ Hubbs et al., 2004, p. 156
  4. ^ a b c Page and Burr, 1991, pp. 45–46
  5. ^ a b Behnke, 2002, p. 335
  6. ^ a b Dickson, 2008, p. 40
  7. ^ Mackay, 2000, pp. 6–8
  8. ^ Alaska Natural Heritage Program, 2005

Literature cited

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