Blue shiner (Cyprinella caerulea)

Description

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Blue shiner fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Blue shiner description

The blue shiner is a member of the Cyprinidae family, a diverse group of fish comprising over 2,000 species. Most of these fish have scaleless heads and lack teeth, instead possessing a pair of enlarged bones in the throat that grind food against a pad at the base of the skull ⁽³⁾. The blue shiner has a dusky blue colouration, with yellow fins and an obvious blue-black line running from the head to the tail ⁽⁴⁾. Light reflecting pigments surround the diamond-shaped scales giving a shiny appearance, a feature that has given rise to the species common name. The blue shiner displays marked sexual dimorphism, and during the breeding season the larger male develops a metallic blue sheen and many tubercles, but the appearance of the somewhat duller female stays constant throughout the year ⁽⁵⁾.

Synonyms

Erogala caeruleus, Notropis caeruleus, Photogenis caeruleus.

Size

Maximum size: 10 cm ⁽²⁾

Blue shiner biology

A rare and little-studied species, much of the blue shiner’s biology is, as yet, undescribed. However, like many other related species, the blue shiner is believed to feed on a variety of terrestrial insects floating on the water surface, often foraging around river margins with overhanging vegetation. This species has a relatively prolonged breeding period, from early May through late August, suggesting females produce multiple clutches each season ⁽⁵⁾. In common with other shiners, males probably attract mates by defending territories and using courtship displays, with spawning taking place in a cavity in submerged wood ^{(4) (5)}. The juvenile fish grow to reach maturity at around two years of age, and have a lifespan of three years ^{(2) (4)}.

Blue shiner range

The blue shiner is endemic to the Coosa River system in the states of Alabama, Georgia and Tennessee in the United States. It is restricted to around six isolated locations, with the most significant population residing in the Conasauga River. Historically, the species was found across a much larger range, including the Cahaba River system and the Mobile Bay drainage area ⁽⁶⁾.

Blue shiner habitat

The blue shiner inhabits small to medium-sized rivers, creeks and pools with clear water, a medium gradient and a sandy or gravel substrate, with a depth of 15 centimetres to 1 metre ^{(2) (6)}. Although the blue shiner may be abundant in areas of suitable habitat, it is typically rare elsewhere, suggesting a high degree of habitat specialisation ⁽⁵⁾.

Blue shiner status

Classified as Vulnerable (VU) on the IUCN Red List ⁽¹⁾.

Blue shiner threats

Numbering no more than 2,500 individuals, the blue shiner population is suspected to have undergone a dramatic decline, although the factors responsible for this are not entirely clear ^{(5) (6)}. A decrease in water quality was probably the most significant agent, as the loss of the species from the Cahaba River coincided with an increase in nitrogen and phosphorous caused by sewage discharge. This led to higher algal biomass and decreased levels of dissolved oxygen in the water ^{(4) (5)}. The blue shiner is also threatened by increased siltation as it relies on sight to detect its prey, while in Georgia, urbanisation and resulting pollution and water extraction threatens the species’ habitat. In many areas the blue shiner now exists in small, highly fragmented populations, which are more vulnerable to habitat degradation and a loss of genetic diversity, greatly increasing the species’ extinction risk ^{(5) (7)}.

Blue shiner conservation

The future of the blue shiner very much depends on the protection of its habitat, particularly the Conasauga River. Fortunately for this rare species, efforts are underway to protect this fragile environment. The Nature Conservancy is working with private landowners and government agencies to protect the Conasauga River and conserve the populations of rare and endangered fish that inhabit its waters ^{(5) (8)}. The National Resources Conservation Service is also working to protect riparian habitat around the Conasauga River and to tackle threats ^{(5) (9)}. The blue shiner will also benefit from further studies into its ecology, threats and population trends ⁽⁵⁾.

View information on this species at the UNEP World Conservation Monitoring Centre.

Find out more

For additional information on the blue shiner, see:

• U.S. Fish and Wildlife Service:
  http://ecos.fws.gov/docs/life_histories/E05Y.html
• NatureServe Explorer:
  http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Cyprinella+caerulea

To find out more on the conservation of the blue shiner, see:

• The Nature Conservancy:
  http://www.nature.org/wherewework/northamerica/states/georgia/preserves/art7310.html
• Conservation Fisheries:
  http://cfi.hubdesigngroup.com/index.php/species/all-species/cyprinella-caerulea-blue-shiner/

Authentication

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Glossary

Endemic

A species or taxonomic group that is only found in one particular country or geographic area.

Genetic diversity

The variety of genes within a particular species, population or breed causing differences in morphology, physiology and behaviour.

Riparian

Relating to the banks of watercourses.

Sexual dimorphism

When males and females of the same species differ in appearance.

Spawning

The production or depositing of large quantities of eggs in water.

Tubercle

A small, rounded, wart-like bump on the skin or on a bone.

References

1. IUCN Red List (April, 2010)
   http://www.iucnredlist.org/
2. U.S. Fish and Wildlife Service Species Account (April, 2010)
   http://ecos.fws.gov/docs/recovery_plan/950830.pdf
3. Campbell, A. and Dawes, J. (2004) Encyclopedia of Underwater Life. Oxford University Press, Oxford.
4. Stephens, C.M. and Mayden, R.L. (1999) Threatened fishes of the world: Cyprinella caerulea Jordan, 1877 (Cyprinidae). Environmental Biology of Fishes, 55: 264.
5. U.S. Fish and Wildlife Service. (1995) Blue Shiner Recovery Plan. U.S. Fish and Wildlife Service, Jackson, Mississippi.
6. NatureServe Explorer (April, 2010)
   http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Cyprinella+caerulea
7. George, A.L., Caldieraro, J.B., Chartrand, K.M. and Mayden, R.L. (2008) Population genetics of the Blue Shiner, Cyprinella caerulea. Southeastern Naturalist, 7: 637-650.
8. The Nature Conservancy (April, 2010)
   http://www.nature.org/wherewework/northamerica/states/georgia/preserves/art7310.html
9. The National Resources Conservation Service (April, 2010)
   http://www.nrcs.usda.gov/FEATURE/buffers/gaconsga.html