Comephorus

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Comephorus
Comephorus baikalensis.jpg
Golomjanka.png
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Scorpaeniformes
Family: Cottidae
Subfamily: Comephorinae
Günther, 1861
Genus: Comephorus
Lacepède, 1800
Type species
Callionymus baikalensis
Pallas, 1776 [1]

Comephorus, known as the golomyankas or Baikal oilfish, are a genus comprising two species of peculiar, sculpin fishes endemic to Lake Baikal in Russia. Comephorus is the only genus in the subfamily Comephorinae. Golomyankas are pelagic fishes and the main food source for the Baikal seal.

Contents

Taxonomy

Comephorus was first proposed as a monospecific genus in 1800 by the French naturalist and politician Bernard Germain de Lacépède with Callionymus baikalensis as its only species. [1] The 5th edition of Fishes of the World places this genus in the monotypic subfamily Comephorinae within the family Cottidae, the typical sculpins. [2] Other authorities have used phylogenetic studies which have found that Baikal sculpins that were classified in the subfamilies Comephorinae and Abyssocottinae by Fishes of the World radiated from an ancestor which was likely to be within the genus Cottus and that the classification of the Baikal sculpins in a different taxon from Cottus was paraphyletic. [3]

Description

Comephorus have translucent bodies with no scales, [4] but appear dull when dead. [5] The big Baikal oilfish (C. baikalensis) can reach up to 21 cm (8.3 in) in length and the little Baikal oilfish (C. dybowskii) up to 16 cm (6.3 in). [6] Males are smaller than females, only reaching about 2⁄3 the length. [7] They have long pectoral fins, and although pelvic bones are present, they lack pelvic fins. They have a strong lateral line. The lateral line system on the head consists of large cavities linked by narrow, bony bridges with small external pores. High lipid content and porous bones result in an almost neutral buoyancy [8] and lack of swim bladder allows the fish to tolerate varying pressure extremes as they move through the water column. Over a third of the body weight (38.9%) of C. baikalensis is oil, but C. dybowskii contains far less (4.7%). [9] It has been said that they decompose in sunlight, leaving behind only fatty oil and bones, [10] although the accuracy of this claim has been questioned. [5] Unusually, their eyes only contain rod cells (not cone cells), indicating a high sensitivity to light. [7] Some of the adaptions in golomyankas resemble those seen in deep sea fish. [8]

Species

There are currently two recognized species in this genus: [6]

Biology and ecology

The common name golomyanka originates from the old-Russian golomen, meaning "far from the shore" in the local dialect and referring to their pelagic behavior. [11] They are the principal ecological competitor to the omul, which also eat small golomyankas, and represent a primary food source for the Baikal seal, at more than 90% of its diet. [5] They are easily identifiable, and are large enough to be easily seen. Golomyankas are unusual for occurring pelagically throughout the entire water column of Lake Baikal, ranging from depths of around 1.6 km (1.0 mi) to near the surface, but they primarily occur deeper than 100 m (330 ft). [12] [13] During the night they move up the water column to feed, often occurring as shallow as 10–25 m (33–82 ft), [14] and in the winter they can occasionally be seen swimming just below the ice-covered surface. [15] They are considered the world's most abyssal freshwater fish, together with certain Lake Baikal deep-water sculpins (Abyssocottidae). [16] They move without much regard for changes in pressure, although they can exist only in cold temperatures, preferring water that is no more than 5 °C (41 °F) and dying at 10 °C (50 °F). [4] [10]

The biomass of the golomyanka population is estimated at about 150 thousand tons, making it the most populous fish in Lake Baikal. [4] [10] It is estimated that about 70% of the fish in the lake are golomyankas. [11] Their juveniles are also the most abundant pelagic fish larvae in the lake. [17] Large shoals are not known for this species, although groups of up to about 20 individuals have been recorded near the lake bottom. [5] Females are more common than males, which only make up about 32% of the population in the little Baikal oilfish and 17% in the big Baikal oilfish. [7] The females do not lay eggs; rather, they are viviparous, giving birth to a swarm of 2000–3000 larvae. [10] Females containing developing embryos can be seen year-round, [7] but there does appear to be a level of seasonality in the birth, with the largest number of larvae occurring from August to April (some differences in the peak timing between the two species). [15] Most females die after giving birth. [4] It has been claimed that their bellies burst open to release the young, killing the female in the process, but this is a myth. [5] Golomyanka can reach an age of up to 6–8 years. [4] [7]

They are sluggish fish, [18] and have relatively large mouths with several rows of somewhat brush-like teeth, allowing them to sift out fine organisms from the water. [7] They primarily feed on the planktonic copepod Epischura baikalensis , the amphipod crustacean Macrohectopus branickii and larvae of sculpins, [19] including those of their own species. [11]

Relationship to humans

A few golomyankas (for example, the pinkish fish on the upper-center part of the photo and another in the lower-left), as well as several whitefish, Baikal yellowfins and amphipods caught during icefishing using a net Ice-fishing on Baikal 5.jpg
A few golomyankas (for example, the pinkish fish on the upper-center part of the photo and another in the lower-left), as well as several whitefish, Baikal yellowfins and amphipods caught during icefishing using a net

Despite being numerous in the lake, golomyankas are difficult to catch in large quantities as they do not gather in large schools. [5] Golomyankas are not harvested commercially, although their fats and oils were used in lamps and as traditional medicine by native Siberians when storms tossed the fish up on shore. [10] They are of no value as a food source for humans, dogs or cats, but are the primary food source for the Baikal seal, and also eaten by other fish in the lake. [5] [11] They are so numerous and spawn so rapidly that they represent the largest concentration of fish biomass within the entire lake, and would seriously unbalance the ecosystem of Lake Baikal if not constantly preyed upon by predators.

See also

Related Research Articles

<span class="mw-page-title-main">Lake Baikal</span> Freshwater rift lake in Russia

Lake Baikal is the deepest rift lake in the world. It is situated in southern Siberia, Russia between the federal subjects of Irkutsk Oblast to the northwest and the Republic of Buryatia to the southeast.

<span class="mw-page-title-main">Baikal seal</span> Species of freshwater seal

The Baikal seal, Lake Baikal seal or nerpa is a species of earless seal endemic to Lake Baikal in Siberia, Russia. Like the Caspian seal, it is related to the Arctic ringed seal. The Baikal seal is one of the smallest true seals and the only exclusively freshwater pinniped species. A subpopulation of inland harbour seals living in the Hudson Bay region of Quebec, Canada,, as well as the Saimaa ringed seal and the Ladoga seal, are also found in fresh water, but these seals are part of species that also have marine populations.

<span class="mw-page-title-main">Cottidae</span> Family of fishes

The Cottidae are a family of fish in the superfamily Cottoidea, the sculpins. It is the largest sculpin family, with about 275 species in 70 genera. They are referred to simply as cottids to avoid confusion with sculpins of other families.

<span class="mw-page-title-main">Abyssocottinae</span> Subfamily of fishes

The Abyssocottinae are a subfamily of ray-finned fishes in the family Cottidae, the sculpins. They are known commonly as the deep-water sculpins. The entire subfamily is endemic to Lake Baikal in Siberia.

<i>Rhamphocottus</i> Genus of fish

Rhamphocottus is a genus of marine ray-finned fishes belonging to the family Rhamphocottidae. These fishes are known as grunt sculpins. The grunt sculpins are found in the North Pacific Ocean.

<i>Cottus</i> (fish) Genus of fishes

Cottus is a genus of the mainly freshwater ray-finned fishes belonging to the family Cottidae, the typical sculpins. They are often referred to as the "freshwater sculpins", as they are the principal genus of sculpins to be found in fresh water. They are native to the Palearctic and Nearctic.

<span class="mw-page-title-main">Fourhorn sculpin</span> Species of fish

The fourhorn sculpin is a species of ray-finned fish belonging to the family Cottidae, the typical sculpins. This species has a Holarctic distribution and can be found in marine, brackish and fresh waters.

<i>Abyssocottus</i> Genus of fishes

Abyssocottus is a genus of ray-finned fishes belonging to the family Cottidae, the typical sculpins. These sculpins are endemic to Lake Baikal in Russia.

Batrachocottus is a genus of freshwater ray-finned fishes belonging to the family Cottidae, the typical sculpins. These fishes are endemic to the Lake Baikal watershed in Russia.

Kessler's sculpin is a species of Baikal sculpin, a freshwater fish native to Russia and Mongolia where it occurs in Lake Baikal and surrounding lakes as well as the Selenga, Angara and Bain Gol rivers. It is the only member of its genus. In Lake Baikal it occurs on sandy, rocky-sandy or sandy-muddy bottoms, ranging from relatively shallow water to depths of 70 m (230 ft). In rivers they mainly occur in slow-flowing channels and floodplains.

The stone sculpin is a species of cottoid fish endemic to Russia, where it is found in Lake Baikal and surrounding tributaries as well as the Gramninskie Lakes, Lake Verkhnaya Agata and the Enisei River and various lakes in Tuva. This species is the only recognized member of its genus.

<span class="mw-page-title-main">Prickly sculpin</span> Species of fish

The prickly sculpin is a species of ray-finned fish belonging to the family Cottidae, the typical sculpins. It is native to the river drainages of the Pacific Slope of North America from Seward, Alaska south to the Ventura River of Southern California. It extends east of the Continental Divide in the Peace River of British Columbia. It has also been introduced to several reservoirs in Southern California.

<i>Abyssocottus korotneffi</i> Species of fish

Abyssocottus korotneffi is a species of ray-finned fish belonging to the family Cottidae, the typical sculpins. These sculpins are endemic to Lake Baikal in Russia. It is known to dwell at a depth range of 120–1,600 m (390–5,250 ft), most commonly between 460–500 m (1,510–1,640 ft). Males can reach a maximum total length of 12.6 cm (5.0 in) and females 13.2 cm (5.2 in). Maximum age is 12 years. Females harbour about 20 eggs in each ovary.

Limnocottus pallidus is a species of ray-finned fish belonging to the family Cottidae, the typical sculpins. This species is endemic to Lake Baikal in Russia. It dwells at a depth range of 150–1000 metres. Males can reach a total length of 13.1 centimetres and females 14.6 cm. L. pallidus can weigh up to 16 grams, and live up to 12 years.

The bighead sculpin is a species of sculpin fish that is endemic to the Lake Baikal watershed in Siberia, Russia. It typically lives on rocky bottoms, often in places with sponges, at depths of 5 to 70 m (16–230 ft), but can occur as deep as 120 m (390 ft). Its colour varies from grayish to brownish or greenish depending on the bottom type. It can reach up to 22 cm (8.7 in) in length, but most are 13–16 cm (5.1–6.3 in). It feeds on a wide range of smaller animals such as young fish, insect larvae, amphipods, molluscs and oligochaetes. Breeding is in the spring where the female lays 618 to 1622 eggs, which are guarded by the male.

<span class="mw-page-title-main">Butterfly sculpin</span> Species of fish

The butterfly sculpin is a species of fish in the family Agonidae. It is found in the North Pacific Ocean.

<span class="mw-page-title-main">Baikal yellowfin</span> Species of fish

The Baikal yellowfin, also known as the yellow-finned sculpin or yellow-wing sculpin, is a species of freshwater ray-finned fish belonging to the family Cottidae, the typical sculpins. This species is endemic to Lake Baikal and its tributaries in Siberia, Russia. It is most common in the southern part of the lake and lives from near the shore to a depth of 300 m (980 ft).

<i>Comephorus baikalensis</i> Species of fish

Comephorus baikalensis, the big Baikal oilfish, is a species of freshwater ray-finned fish belonging to the family Cottidae, the typical sculpins. This fish is endemic to Lake Baikal in Russia.

Comephorus dybowskii, the little Baikal oilfish, is a species of freshwater ray-finned fish belonging to the family Cottidae, the typical sculpins. This fish is endemic to Lake Baikal in Russia.

References

  1. 1 2 Eschmeyer, William N.; Fricke, Ron & van der Laan, Richard (eds.). "Genera in the family Cottidae". Catalog of Fishes . California Academy of Sciences . Retrieved 4 March 2023.
  2. ↑ J. S. Nelson; T. C. Grande; M. V. H. Wilson (2016). Fishes of the World (5th ed.). Wiley. pp. 467–495. ISBN   978-1-118-34233-6. Archived from the original on 2022-06-01. Retrieved 2023-03-04.
  3. ↑ W. Leo Smith & Morgan S. Busby (2014). "Phylogeny and taxonomy of sculpins, sandfishes, and snailfishes (Perciformes: Cottoidei) with comments on the phylogenetic significance of their early-life-history specializations". Molecular Phylogenetics and Evolution. 79: 332–352. doi:10.1016/j.ympev.2014.06.028. PMID   25014569.
  4. 1 2 3 4 5 Animals and plants of Lake Baikal from Irkutsk State University, accessed May 5, 2006
  5. 1 2 3 4 5 6 7 "Mysterious Fish of Lake Baikal". Science First Hand. 30 September 2004. Retrieved 31 May 2017.
  6. 1 2 Froese, Rainer; Pauly, Daniel (eds.). "Species in genus Comephorus". FishBase . December 2012 version.
  7. 1 2 3 4 5 6 "ГОЛОМЯНКИ, ЧАСТЬ 2: ОСОБЕННОСТИ СТРОЕНИЯ" (in Russian). Fishwatching. 29 January 2016. Retrieved 5 March 2018.
  8. 1 2 Sideleva, V.G. (1996). Comparative character of the deep-water and inshore cottoid fishes endemic to Lake Baikal. Journal of Fish Biology 49(sA): 192–206.
  9. ↑ Kozlova, T. A.; Khotimchenko, S. V. (August 2000). "Lipids and fatty acids of two pelagic cottoid fishes (Comephorus spp.) endemic to Lake Baikal". Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology. 126 (4): 477–485. doi:10.1016/S0305-0491(00)00207-8. PMID   11026659.
  10. 1 2 3 4 5 Ichthyofauna of Lake Baikal from Baikal Web World, accessed May 5, 2006 (with a photo of the golomyanka).
  11. 1 2 3 4 "Baikal "shark": Amazing fact about the Baikal oilfish (golomyanka)". Key to Baikal. 19 May 2017. Retrieved 31 May 2017.
  12. ↑ Froese, Rainer; Pauly, Daniel (eds.). "Comephorus baikalensis". FishBase . September 2016 version.
  13. ↑ Froese, Rainer; Pauly, Daniel (eds.). "Comephorus dybowskii". FishBase . September 2016 version.
  14. ↑ Goodman, S. (2016). "Pusa sibirica". IUCN Red List of Threatened Species . 2016: e.T41676A45231738. doi: 10.2305/IUCN.UK.2016-1.RLTS.T41676A45231738.en . Retrieved 13 November 2021.
  15. 1 2 "ГОЛОМЯНКИ, ЧАСТЬ 1: ЭКОЛОГИЯ ВИДОВ" (in Russian). Fishwatching. 21 January 2016. Retrieved 5 March 2018.
  16. ↑ Hunt, D. M., et al. (1997). Molecular evolution of the cottoid fish endemic to Lake Baikal deduced from nuclear DNA evidence. Molecular Phylogenetics and Evolution 8(3), 415-22.
  17. ↑ Dzyuba, E.V. (2006). Two coexisting species of Baikal golomyankas, Comephorus baicalensis and C. dybowski: seasonal dynamics of juveniles and their feeding. Hydrobiologia 568, Supplement 1: 111–114.
  18. ↑ Jakubowski, Tugarina, and Żuwała (2003). Pectoral fin development in the Baikalian viviparous golomyankas (Comephoridae; Cottoidei), with a remark on eggs and embryos of Comephorus baicalensis (Pallas). J.Anat. 203(3): 317-322.
  19. ↑ Miyasaka, Dzyuba, Genkai-Kato and Wada (2006). Feeding ecology of two planktonic sculpins, Comephorus baicalensis and Comephorus dybowskii (Comephoridae), in Lake Baikal. Ichthyological Research 53(4): 419-422.
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