Ballan wrasse

The ballan wrasse (Labrus bergylta) is a species of marine ray finned fish from the family Labridae, the wrasses. It is found in the eastern Atlantic Ocean, where it inhabits rocky areas. Like many wrasse species, it is a protogynous hermaphrodite—all fish start life as females, and some dominant fish later become males. It is used as a food fish in some areas and it is also finding use as a cleaner fish in the aquaculture of Atlantic salmon (Salmo salar) in northwestern Europe.

Ballan wrasse
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Labriformes
Family: Labridae
Genus: Labrus
Species:
L. bergylta
Binomial name
Labrus bergylta
Ascanius, 1767
Synonyms[2]
  • Labrus comber Bonnaterre, 1788
  • Labrus ballan Bonnaterre, 1788
  • Labrus maculatus Bloch, 1792
  • Labrus neustriae Lacépède, 1801
  • Labrus balanus J. Fleming, 1828
  • Labrus variabilis W. Thompson, 1837
  • Crenilabrus multidentatus W. Thompson, 1837
  • Labrus reticulatus R. T. Lowe, 1839
  • Labrus donovani Valenciennes, 1839
  • Labrus nubilus Valenciennes, 1843

Description

The ballan wrasse is a large, heavy bodied wrasse with a relatively deep body and large head. It has a smallish mouth which is surrounded by thick, fleshy, rather wrinkled lips, and the jaws are armed with a single row of robust teeth which are sharp and pointed in young fish but blunter and more worn in older fish. It has a long dorsal fin which has 18–21 spines in its anterior portion and 9–13 branched rays in the rear part. The anal fin is markedly shorter and has three spines. It has large scales with 41–47 of them in the lateral line. The juvenile fish are coloured to match their habitat and vary in from light green to dark green,[3] with some being described as bright emerald green.[4] The adults are more variable in colour, as they can either be dark green or reddish brown but are marked all over with numerous white spots.[3] It can grow to 65.9 cm (25.9 in) in total length (though most do not exceed 50 cm (20 in) standard length), and the greatest recorded weight of this species is 4.4 kg (9.7 lb). Ballan wrasses are prototgynous hermaphrodites.[2]

Distribution

Ballan wrasse are native to the northeastern Atlantic Ocean from Norway to Morocco, including the islands of Madeira, the Azores and the Canary Islands. There are records from the Mediterranean Sea but these are regarded as questionable[1] and may be misidentifications of the brown wrasse (Labrus merula).[2]

Habitat and biology

They can be found at depths from 1 to 50 m (3.3 to 164.0 ft) amongst rocks, seaweed and reefs. All ballan wrasses are female for their first four to 14 years before a few change into males. Large fish of the species are almost certainly male.[2] The thick lips and sharp front teeth of the ballan wrasse are an adaptation for extracting shellfish from rocks. These are supplemented by powerful pharyngeal teeth which are placed further back in the throat and which can break up shells to access flesh inside. This species also feeds on crustaceans and their diet includes hard-shelled crabs and small lobsters. They will swim into shallower water so that they can prey on the shellfish which cling to underwater cliff faces and inshore rocks. They will also inhabit areas with good covering of kelp and other seaweeds.[5] The male builds a nest of algae in a crevice in the rocks in which one or more females lay eggs. The male defends the nest until the eggs hatch into pelagic larvae after a week or two.[1]

Ballan wrasse do not have stomachs.[6]

Human usage

Fishery and Sport

This species is popular as a food fish in the Orkney Islands off the north-eastern coast of Scotland, and in Galway, a county in the west of Ireland.[7] However, it is not highly regarded as a food fish in much of the UK and Ireland.[5] In recent years, it has become a popular catch-and-release target for sport fishermen using light fishing tackle, particularly those employing soft plastic lures.[8][5]

Aquaculture

This fish is one of 5 key species used as cleaner fish to remove sea lice from Norwegian[9] and Scottish[10][11] farmed salmon, with 3,317,000 fish used in Atlantic salmon and rainbow trout sea pens in 2020 in Norway alone.[12] Along with lumpfish, this species is farmed for this purpose.

As with many farmed marine species, commercial larval rearing utilises live prey before transitioning to dry feeds after metamorphosis is complete.[6] The majority of the industry currently uses enriched rotifers and Artemia, but copepod nauplii (Acartia tonsa) and barnacle nauplii (Semibalanus balanoides) are becoming more common as alternatives.[6][13]

This species can also be found in the aquarium trade.[2]

References
  1. Pollard, D. (2010). "Labrus bergylta". IUCN Red List of Threatened Species. 2010: e.T187398A8525211. doi:10.2305/IUCN.UK.2010-4.RLTS.T187398A8525211.en. Retrieved 20 November 2021.
  2. Froese, Rainer; Pauly, Daniel (eds.) (2006). "Labrus bergylta" in FishBase. April 2006 version.
  3. Alwyne Wheeler (1997) [1992]. The Pocket Guide to Salt Water Fishes of Britain and Europe. Parkgate Books. p. 117. ISBN 978-1855853645.
  4. O. E. D. Ager (2008). H. Tyler-Walters; K. Hiscock (eds.). "Ballan wrasse (Labrus bergylta)". Marine Life Information Network. Marine Biological Association of the United Kingdom. Retrieved 14 January 2020.
  5. "Wrasse". BritishSeaFishing. 23 November 2013. Retrieved 14 January 2020.
  6. Gagnat, Maren Ranheim; Wold, Per-Arvid; Bardal, Tora; Øie, Gunvor; Kjørsvik, Elin (2016-09-15). "Allometric growth and development of organs in ballan wrasse (Labrus bergylta Ascanius, 1767) larvae in relation to different live prey diets and growth rates". Biology Open. 5 (9): 1241–1251. doi:10.1242/bio.017418. ISSN 2046-6390. PMC 5051651. PMID 27422903.
  7. Alan Davidson, North Atlantic Seafood, 1979, ISBN 0-670-51524-8
  8. David Erwin, Bernard Picton, "Guide to Inshore Marine Life" The Marine Conservation Society 1987 ISBN 0-907151-34-5
  9. "New approach to combating sea lice: Wrasse to the rescue". The Research Council of Norway. 2010-04-23 – via ScienceDaily.
  10. "Western Isles salmon farm in wrasse 'first'". BBC News. 2012-10-09.
  11. Brooker, Adam J; Papadopoulou, Athina; Gutierrez, Carolina; Rey, Sonia; Davie, Andrew; Migaud, Herve (September 2018). "Sustainable production and use of cleaner fish for the biological control of sea lice: recent advances and current challenges". Veterinary Record. 183 (12): 383–383. doi:10.1136/vr.104966. hdl:1893/27595.
  12. "Akvakulturstatistikk: rensefisk". Fiskeridirektoratet (in Norwegian). Retrieved 2021-09-30.
  13. Malzahn, Arne M.; Ribičić, Deni; Hansen, Bjørn Henrik; Sarno, Antonio; Kjørsvik, Elin; Aase, Anna Sigrid Norberg; Musialak, Luciana Alves; García-Calvo, Laura; Hagemann, Andreas (December 2022). "First feed matters: The first diet of larval fish programmes growth, survival, and metabolism of larval ballan wrasse (Labrus bergylta)". Aquaculture. 561: 738586. doi:10.1016/j.aquaculture.2022.738586.
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