|Scientific Name:||Ctenochaetus hawaiiensis|
|Species Authority:||Randall, 1955|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor/s:||McIlwain, J., Clements, K.D., Choat, J.H., Abesamis, R., Myers, R., Nanola, C., Rocha, L.A., Russell, B. & Stockwell, B.|
|Reviewer/s:||Edgar, G. & Kulbicki, M.|
Ctenochaetus hawaiiensis is widespread and uncommon in parts of its range. It is a component of the aquarium trade and is the 5th most collected aquarium fish in western Hawaii. It is known to be harvested primarily from the west coast of the big island of Hawaii. There have been decreases in density in western Hawaii, however this decrease in overall density is not significant. Moreover, the Fish Replenishment Areas (FRAs) established in western Hawaii have been shown to be effective in terms of increases in the FRAs relative to long term marine protective areas. In addition, harvest levels and and trade are closely monitored in Hawaii and this species occurs in a number of marine protected areas in parts of its range. It is therefore listed as Least Concern.
|Range Description:||Ctenochaetus hawaiiensis is widespread in the tropical Pacific from Ryukyu Islands, Japan and southwest Palau islands to the Pitcairn group including most of Micronesia and French Polynesia (except Rapa), and north to the main Hawaiian Islands.|
Native:American Samoa (American Samoa); Cook Islands; French Polynesia; Guam; Japan; Kiribati (Gilbert Is., Kiribati Line Is., Phoenix Is.); Marshall Islands; Micronesia, Federated States of ; Nauru; Niue; Northern Mariana Islands; Palau; Pitcairn; Samoa; Tokelau; Tonga; Tuvalu; United States (Hawaiian Is.); United States Minor Outlying Islands (Howland-Baker Is., Johnston I., Midway Is., US Line Is., Wake Is.); Wallis and Futuna
|FAO Marine Fishing Areas:||
Pacific – eastern central; Pacific – northwest; Pacific – southwest; Pacific – western central
|Range Map:||Click here to open the map viewer and explore range.|
Ctenochaetus hawaiiensis is relatively common in the Hawaiian Islands. It is relatively uncommon throughout Micronesia (R.F. Myers pers. comm. 2010). It is a minor component in the commercial landings in Hawaii, 90 kg recorded in 2007 (Hawaii Division of Aquatic Resources unpub. data). It is the fifth most collected aquarium fish in West Hawaii. There was a non-significant decrease in overall density across Fish Replenishment Areas (FRAs) surveyed from 1999-2009. However, the FRAs were shown to be effective in terms of increases inside the FRAs relative to long term marine protected areas. There was minimal recruitment into West Hawaii in the last decade: 0.05/100 m2. The deeper areas where the West Hawaii Aquarium Project transects are located is not the prime habitat for adults of this species. Ctenochaetus hawaiiensis inhabits high energy shallow surge zones. For FY 2005-2009, the total number of individuals caught was 19,631 with a total value of $309,808 (Walsh et al. 2010). There was a change in abundance recorded from nine monitoring stations in Fish Replenishment Areas (FRAs) in West Hawaii. FRAs were closed to aquarium collecting in 2000. Prior to establishment of FRAs density was recorded at 0.23 individuals/100 m2 and after establishment density was 0.39 individuals/100 m2 (Friedlander et al. 2006).
It was observed in Tuvalu but was noted as rare (Randall and Clements 2001). It seemed to be quite uncommon in the northwest Hawaiian Islands. It was not observed at the French Frigate Shoals, Pearl and Hermes or Midway (K.D. Clements pers. comm. 2010). Overall aquarium catch in fiscal years 2004 through 2006 reported 5,867 individuals caught per year and a value of $91, 016 per year (Friedlander et al. 2006). It is rare in the American Samoa National Park (National Park of Samoa Checklist of Fishes, accessed 21 April 2010).
|Habitat and Ecology:||
Ctenochaetus hawaiiensis inhabits high energy shallow surge zones (Walsh et al. 2010). The genus Ctenochaetus feed on fine detrital material. They whisk the sand or rocky substratum with their teeth and utilize suction to draw in the detrital material that consists of diatoms, small fragments of algae, organic material and fine inorganic sediment (Randall and Clements 2001). Species of Ctenochaetus share the presence of a thick-walled stomach (Randall and Clements 2001), this character is significant with respect to the nutritional ecology of this genus (Choat et al. 2002b).
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).
Ctenochaetus hawaiiensis is a popular aquarium species. In West Hawaii, it is the 5th most collected aquarium fish. Surveys since 1999 show that there is minimal recruitment (Walsh et al. 2010).
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:||In Hawaii, nine Fish Replenishment Areas were established in 2000. These areas prohibit marine aquarium organism collecting within approximately 30% of the Kona coast nearshore habitat (Kusumaatmadja et al. 2004). Its distribution overlaps with several marine protected areas in parts of its range.|
|Citation:||McIlwain, J., Clements, K.D., Choat, J.H., Abesamis, R., Myers, R., Nanola, C., Rocha, L.A., Russell, B. & Stockwell, B. 2012. Ctenochaetus hawaiiensis. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 21 April 2014.|
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