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Thalassoma bifasciatum

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA ACTINOPTERYGII PERCIFORMES LABRIDAE

Scientific Name: Thalassoma bifasciatum
Species Authority: (Bloch, 1791)
Common Name(s):
English Blue head, Bluehead wrasse, Blue mah, Doctor fish, Parrotfish, Tikitiki
Spanish Cara de cotorra, Loro cabeza azul
Synonym(s):
Bermudichthys subfurcatus Nichols, 1920
Bermudichthys subfurcatus Nichols, 1920
Julis detersor Val, 1839
Julis detersor Val, 1839
Julis gillianus Poey, 1860
Julis gillianus Poey, 1860
Julis nitida Günther, 1862
Julis nitida Günther, 1862
Julis nitidissima Goode, 1877)
Julis nitidissima Goode, 1877)
Labrus bifasciatus Bloch, 1791
Labrus bifasciatus Bloch, 1791
Labrus bifasciatus subspecies torquatus Bloch & Schneider, 1801
Labrus bifasciatus subspecies torquatus Bloch & Schneider, 1801
Labrus ornatus Gronow, 1854
Labrus ornatus Gronow, 1854
Labrus torquatus Walbaum, 1792
Labrus torquatus Walbaum, 1792
Thalassoma bisfaciatum (Bloch, 1791)
Thalassoma bisfaciatum (Bloch, 1791)
Thalassoma nitida (Günther, 1862)
Thalassoma nitida (Günther, 1862)

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2010
Date Assessed: 2008-04-12
Assessor(s): Shea, S., Liu, M. & Sadovy, Y.
Reviewer(s): Craig, M.T. & Carpenter, K.E.
Justification:
This species is widespread in the northwestern Atlantic and is common in many parts of its range. Although it is collected for the aquarium trade, and is closely associated with reef habitat, these are not currently considered to be a threat to this species global population. It listed as Least Concern.

Geographic Range [top]

Range Description: This species is common in the tropical waters of the western central Atlantic Ocean, and is found in Bermuda, Florida, the Gulf of Mexico, and the Caribbean Sea to Venezuela and Trinidad and Tobago.
Countries:
Native:
Anguilla; Antigua and Barbuda; Bahamas; Barbados; Belize; Bermuda; Bonaire, Sint Eustatius and Saba (Saba, Sint Eustatius); Cayman Islands; Colombia; Costa Rica; Cuba; Curaçao; Dominica; Dominican Republic; Grenada; Guadeloupe; Guatemala; Haiti; Honduras; Jamaica; Martinique; Mexico; Montserrat; Nicaragua; Panama; Puerto Rico; Saint Kitts and Nevis; Saint Lucia; Saint Martin (French part); Saint Vincent and the Grenadines; Sint Maarten (Dutch part); Trinidad and Tobago; Turks and Caicos Islands; United States; Venezuela, Bolivarian Republic of; Virgin Islands, British; Virgin Islands, U.S.
FAO Marine Fishing Areas:
Native:
Atlantic – western central
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: This species is common throughout the northwest Atlantic (Warner 1984) and Caribbean coral reefs (Herbing and Hunte 1991, Warner and Schultz 1992). It is one of the most abundant species throughout the West Indies (Florida Museum of Natural History-Ichthyology Department).

Through a series of underwater visual surveys, 1,334 individuals and 2,335 individuals were observed in La Parguera Region, Puerto Rico and Rincón Region, Puerto Rico, respectively, and this species has been observed to be one of the most abundant reef fish species in both regions (Richard et al. 2006). In the Virgin Islands (USA), fish density has been reported at 3.4 individuals m2 and over 10,000 individuals have been observed at any one time at the aggregation (Warner 1995). It is one of the most frequently sighted species in Bonaire reefs, Netherlands Antilles (Pattengill-Semmens undated), and 5,087 individuals were observed in Barbados Marine Reserve, Barbados between August and December, in 1992 (Rakitin and Kramer 1996).

In addition, it is known that population varies according to the size of reefs, with about 200 individuals living on a small reef (under 600 m2) and up to 10,000 individuals on some of the larger reefs (over 1,000 m2) (Warner 1984).
Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology: This species is one of the best-studied protogynous hermaphrodites (Warner and Swearer 1991, Schärer and Vizoso 2003, Munday et al. 2006). It occurs in tropical waters and associates with coral reefs to depths of at least 40 m, and is also known to inhabit inshore bays and seagrass beds. Tagging studies showed that adults do not leave the reef upon which they have settled (Warner and Hoffman 1980).

Individuals feed primarily on zooplankton and small benthic crustaceans (Warner and Hoffman 1980), including echinoderms (sea stars, brittle stars), molluscs and polychaetes, in addition, diet consists of ectoparasites found on other fishes (Deloach 1999).

This species occurs in two major colour phases, initial phase individuals can be either males or females. The common terminal phase individuals are males and tend to be the largest individuals in any local population (Warner and Robertson 1978). Large females are able to change sex into secondary males (Warner et al. 1975). Sex change and the transition to terminal phase coloration are reported to be controlled by local social conditions (Warner et al. 1975).

Spawning occurs on a daily basis throughout the year (Warner et al. 1975, Warner and Robertson 1978, Warner and Hoffman 1980, Fitch and Shapiro 1990), for about an hour in mid afternoon. Fertilization is external and there is no parental care of the pelagic zygotes (Warner and Hoffman 1980, Warner 1984). Randall and Randall (1963), however, noted that reproduction seemed to occur mostly within a period of a few days during the full moon and to a lesser extent, new moon. During the mating period, the majority of males are located at the down-current end of the reef, where they attempt to mate with the arriving females. T. bifasciatum is noted as resident spawning aggregation which is aggregated by locally abundant populations from the same reef (Domeier and Colin 1997). Seasonal recruitment was found in Barbados, West Indies and spawning was found to occur primarily between January and August (Herbing and Hunte 1991).

The largest terminal phase males aggressively defend breeding sites and therefore gain exclusive access to females visiting the site, conversely, initial phase females or males have no territorial defense and are much less aggressive (Warner 1984). The mean home range of adults is approximately eight m2 at Tague Bay, St. Croix, U.S. Virgin Island, while for juveniles it was less than two m2 (Jones 2005). The home range area was positively correlated with the fish total length

It has been found that the predators of this species include Aulostomus maculates, Epinephelus guttatus, Myceteropera venenosa and Rypticus saponaceus. Length at sex change has been reported at 8.3 cm TL (Allsop and West 2003) and individual fish mature at 3.5 cm SL, size approximately 30 % of the maximum size (Warner 1998). Evidence showed that the final body sizes might have a strong influence on maturity sizes (Robertson 1972, Warner and Swearer 1991). Minimum population doubling time is less than 15 months (Froese and Pauly 2008) and maximum lifespan is estimated to be three years for individuals reaching the terminal phase (Warner 1998).

Eggs hatch at 1.4 mm (Cato and Brown 2003). Larvae are approximately 12 mm in length and the pelagic larval duration has been found to be 38 to 54 days (Philibotte 2002).
Systems: Marine

Use and Trade [top]

Use and Trade: This species has been noted as one of the ‘top ten’ species of fish on the export list in Florida (Wood 2001) and Puerto Rico (Sadovy 1992). An ornamental fishery evaluation study found that 844 individuals were harvested per annum across the La Parguera and Rincón Regions, Puerto Rico (Richard et al. 2006).

Threats [top]

Major Threat(s): There are no major threats known for this species, although it is closely associated with coral reefs and shows high site fidelity. Adults remain on their home reefs, with no emigration or immigration after settlement (Warner and Hoffman 1980).

Habitat destruction may pose a local threat to this species.

Conservation Actions [top]

Conservation Actions: There are no specific conservation measures in place for this species. Its distribution overlaps several marine protected areas within its range.

This species is found in marine reserves in the Florida Keys National Marine Sanctuary, USA (Grorud-Colvert 2006), Hol Chan Marine Reserve, Belize (National Parks of Belize), Barbados Marine Reserve, Barbados (Cheney and Côté 2003), Barbados Marine Park (Rakitin and Kramer 1996) and Bonaire Marine Park, Bonaire (Pattengill-Semmens undated). It is worth noting that Barbados Marine Park does not imply as a no-take zone, baited fishing and trawling are still allowed within the areas and currently two non-fishing zones are being proposed (STINAPA Bonaire 2007).

While many marine parks have already been introduced in areas within the geographic range of T. bifasciatum, it is worth noting that the degree of protection within marine reserve varies according to the effectiveness of management. Currently, there is little information on the effectiveness of those marine parks, therefore, more information is necessary to establish its conservation status.

Citation: Shea, S., Liu, M. & Sadovy, Y. 2010. Thalassoma bifasciatum. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 22 December 2014.
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