Naso thynnoides 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Actinopterygii Perciformes Acanthuridae

Scientific Name: Naso thynnoides (Cuvier, 1829)
Common Name(s):
English Singlespine Unicornfish, Barred Unicornfish, Oneknife Unicornfish, One-spine Unicorn, Thunny Unicornfish
Axinurus thynnoides Cuvier, 1829
Naso thynoides (Cuvier, 1829)

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2012
Date Assessed: 2010-05-06
Assessor(s): Abesamis, R., Choat, J.H., Clements, K.D., McIlwain, J., Myers, R., Nanola, C., Rocha, L.A., Russell, B. & Stockwell, B.
Reviewer(s): Edgar, G. & Kulbicki, M.
Naso thynnoides is widespread in the Indo-Pacific region. It is common and can be locally abundant. It is a targeted food fish in parts of its range and is occasionally seen in fish markets. There may be some localized declines through harvesting, however it is not considered a major threat to the global population. It is found in several Marine Protected Areas within its range. It is therefore listed as Least Concern.

Geographic Range [top]

Range Description:Naso thynnoides is widespread from East Africa to the Marshall and Solomon Islands, northwards to the Ryukyu Islands, south to the Solomon Islands and the Great Barrier Reef. It is also known from American Samoa, Johnston Atoll and Tuamoto archipelago. It is probably more widespread in the central Pacific than current records indicate (R.F. Myers pers. comm. 2010).
Countries occurrence:
American Samoa; Australia; British Indian Ocean Territory; Comoros; French Polynesia; French Southern Territories (Mozambique Channel Is.); Guam; India (Andaman Is., Nicobar Is.); Indonesia; Japan; Kenya; Madagascar; Malaysia; Maldives; Marshall Islands; Mauritius; Mayotte; Micronesia, Federated States of ; Mozambique; Myanmar; Northern Mariana Islands; Palau; Papua New Guinea; Philippines; RĂ©union; Samoa; Seychelles; Solomon Islands; Sri Lanka; Taiwan, Province of China; Tanzania, United Republic of; Thailand; Timor-Leste; Tonga; United States Minor Outlying Islands (Johnston I.)
FAO Marine Fishing Areas:
Indian Ocean – western; Indian Ocean – eastern; Pacific – eastern central; Pacific – northwest; Pacific – western central
Additional data:
Lower depth limit (metres):50
Upper depth limit (metres):2
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Naso thynnoides is generally rare, but several large schools were observed in Milne Bay Province, Papua New Guinea (Allen 2003). Occasional large schools were observed at Raja Ampat, Indonesia (Allen 2003b). It is common and locally abundant in the Philippines (R. Abesamis and C. Nanola pers. comm. 2010).

The catch composition of the Apo Island fishery in the Philippines is dominated by a few fish families, Acanthuridae being one of the five families accounting for about 50-90% of the catch. Reef and reef-associated species became more dominant in the catch over the years. In particular, an increasing proportion of carangids and acanthurids was observed in the catch over time. The proportion of Acanthuridae total catch almost doubled over the study period (16% in 1980/81 to 27% in 2000/2001) (Maypa et al. 2002).

In Kenya, landings during 1978-2001 for families that are less important in commercial catches (e.g., scarinae and Acanthuridae) showed rising catches (1978-1984) followed by a general decline during the 1990s, but the landings for the scarinae showed a rising trend in recent years (Kaunda-Arara et al. 2003).
Current Population Trend:Stable
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:Naso thynnoides is usually seen in small roving aggregations feeding on zooplankton. It occurs both in the protected waters of lagoons and in exposed outer reef areas from the shallows to at least 40 m, but generally more than 10 m. It sleeps on reefs at night at which time it takes on a disruptive mottled color pattern. The maximum age recorded was 4-5 years. N. thynnoides has high turnover rate (R. Abesamis & J.H. Choat pers comm. 2010).

The sexes are separate among the acanthurids (Reeson 1983). Acanthurids do not display obvious sexual dimorphism, males assume courtship colours (J.H. Choat pers. comm. 2010).


Use and Trade [top]

Use and Trade: Naso thynnoides is captured for food. In Apo Island, Philippines, it is caught by gill nets and traps (Maypa et al. 2002). It is occasionally seen in markets.

Threats [top]

Major Threat(s): Fishing may cause some localized declines.

Surgeonfishes show varying degrees of habitat preference and utilization of coral reef habitats, with some species spending the majority of their life stages on coral reef while others primarily utilize seagrass beds, mangroves, algal beds, and /or rocky reefs. The majority of surgeonfishes are exclusively found on coral reef habitat, and of these, approximately 80% are experiencing a greater than 30% loss of coral reef area and degradation of coral reef habitat quality across their distributions. However, more research is needed to understand the long-term effects of coral reef habitat loss and degradation on these species' populations. Widespread coral reef loss and declining habitat conditions are particularly worrying for species that recruit into areas with live coral cover, especially as studies have shown that protection of pristine habitats facilitate the persistence of adult populations in species that have spatially separated adult and juvenile habitats (Comeros-Raynal et al. 2012).

Conservation Actions [top]

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

Citation: Abesamis, R., Choat, J.H., Clements, K.D., McIlwain, J., Myers, R., Nanola, C., Rocha, L.A., Russell, B. & Stockwell, B. 2012. Naso thynnoides. The IUCN Red List of Threatened Species 2012: e.T177980A1509761. . Downloaded on 19 September 2017.
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