Monotaxis grandoculis 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Actinopterygii Perciformes Lethrinidae

Scientific Name: Monotaxis grandoculis (Forsskål, 1775)
Common Name(s):
English Humpnose Big-eye Bream, Bigeye Barenose, Bigeye Bream, Bigeye Emperor
French Brème Aux Gros Yeux , Capitaine Bossu, Daurade Tropicale, Dorade à Gros Yeux, Empereur Bossu, Gueule Pavée
Spanish Emperador Jorobado
Sciaena grandoculis Forsskål, 1775
Taxonomic Source(s): Eschmeyer, W.N., Fricke, R. and Van der Laan, R. (eds). 2016. Catalog of Fishes: genera, species, references. Updated 29 September 2016. Available at: (Accessed: 29 September 2016).

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2016
Date Assessed: 2015-03-09
Assessor(s): Carpenter, K.E., Lawrence, A. & Myers, R.
Reviewer(s): Ralph, G. & Linardich, C.
Facilitator/Compiler(s): Ralph, G.
Monotaxis grandoculis is widely distributed. This species is among the most extensively harvested lethrinids in many parts of its range and is experiencing some localized population declines. It is subject to management in American Samoa, Guam and the Commonwealth of the Mariana Islands as part of the Bottomfish Management Unit. Global level declines are not suspected at this time; therefore, this species is assessed as Least Concern. Monitoring is strongly recommended in areas where fishing pressure is high.

Geographic Range [top]

Range Description:Monotaxis grandoculis is widespread in the Indo-West and Central Pacific from Hawaii and southeastern Oceania to the East Africa and Red Sea and from Australia northwards to Japan. It is typically found at depths of 3-60 m (Carpenter 2001), but has been recorded to 150 m (R. Myers pers. comm. 2015). This species has recently invaded the Mediterranean Sea through the Suez Canal (Bilecenoglu 2007).
Countries occurrence:
American Samoa; Australia; British Indian Ocean Territory; Brunei Darussalam; Cambodia; China; Christmas Island; Cocos (Keeling) Islands; Comoros; Cook Islands; Disputed Territory (Paracel Is., Spratly Is.); Djibouti; Egypt; Eritrea; Fiji; French Polynesia; French Southern Territories (Mozambique Channel Is.); Guam; India; Indonesia; Israel; Japan; Jordan; Kenya; Kiribati (Gilbert Is., Kiribati Line Is., Phoenix Is.); Korea, Republic of; Madagascar; Malaysia; Maldives; Marshall Islands; Mauritania; Mayotte; Micronesia, Federated States of ; Mozambique; Myanmar; Nauru; New Caledonia; Niue; Northern Mariana Islands; Oman; Palau; Papua New Guinea; Philippines; Pitcairn; Réunion; Samoa; Saudi Arabia; Seychelles; Solomon Islands; Somalia; South Africa; Sri Lanka; Sudan; Taiwan, Province of China; Tanzania, United Republic of; Thailand; Timor-Leste; Tokelau; Tonga; Tuvalu; United States (Hawaiian Is.); United States Minor Outlying Islands (Howland-Baker Is., US Line Is., Wake Is.); Vanuatu; Viet Nam; Wallis and Futuna; Yemen
FAO Marine Fishing Areas:
Indian Ocean – western; Indian Ocean – eastern; Pacific – western central; Pacific – southwest; Pacific – northwest; Pacific – eastern central
Additional data:
Lower depth limit (metres):60
Upper depth limit (metres):3
Range Map:Click here to open the map viewer and explore range.

Population [top]


From 2008-2014, regional estimates of the density of M. grandoculis ranged from 6.3-28.4 individuals per hectare over hard bottoms to 30 m depth in Pacific coral reef areas surveyed by NOAA (NOAA unpublished data as described in Heenan et al. 2014). The highest density was in the North Western Hawaiian Islands region (2.0-62.3 individuals per hectare) as compared to the lowest, in the Main Hawaii Islands region (2.7-15.2 individuals). The species was not recorded in the Hawaiian Islands or the Northern Marianas Islands region (NOAA unpublished data as described in Heenan et al. 2014). 

In Fiji, density of this species was shown to be 68.6/ha (S. Jupiter unpublished data). Density of this species in the Federated States of Micronesia ranged from 2.8/ha (Guam) to 56.7/ha (Ifalik) (B. Taylor, unpublished data). In the Solomon Islands, surveys from the populous islands showed a mean density of 132.7/ha and surveys around the remote islands showed a mean density of 546.2/ha (A. Green, unpublished data). This species is abundant in the Solomon Islands and is one of the most common lethrinids (Allen 2006). Mean density for this species in Raja Ampat 0.6/ha (A. Green, unpublished data). 

East Africa and Western Indian Ocean
In the Kalimani Wildlife Management Area, Papua New Guinea, the mean fork length of 76 specimens was 24 cm and decreased from 2013 to 2014. This is 67% of the estimated length of female maturity (36 cm), and 43% of the maximum length (56 cm)(Longenecker et al. 2014).

All of the M. grandoculis taken in the multi-gear fishery of southern Kenya were well below lengths of first maturity. The length at first capture was 19.2 cm, while the length at maturity was 31.8 cm. This species was not very abundant in the fishery (Mangi and Roberts 2006).

This species is not managed within the bottomfish resource management unit in American Samoa, the Commonwealth of the Northern Mariana Islands, and Guam. It is considered an "other bottomfish". Bottomfish complexes were not depleted and were not experiencing overfishing in 2010. The status of this stock is based on fishery-dependent data, and there are currently no fishery-independent measures of relative or absolute bottom-fish abundance (Brodziak et al. 2012). Abundant and most common lethrinid in Solomon Islands (Allen 2006).

In Fiji, all of the individuals (n=9) either landed, sold or consumed were below the minimum length at maturity (Cakacaka et al. 2010). This species was the 9th most common species in the coral reef fishery of Pohnpei, Micronesia (Rhodes et al. 2008).

American Samoa
The commercial bottomfish fishery in American Samoa was established from 1982-1985. Of all bottomfish species landed in American Samoa L. rubioperculatus and other emperors, Etelis corruscans and Lutjanus kasmira are the top landings in pounds comprising about 77% of total landings. The relative contribution of M. grandoculis to the catch is currently unknown. Stock assessment of Bottomfish Management Unit Species (BMUS) indicated below maximum sustainable yield. Decline in bottomfishing catch has occurred with decline in effort in American Samoa. Additionally, declines in adjusted price of fish suggest declining fish consumption. In 2011, this species accounted for 11% of all bottomfish landings (3987 lbs/35,808 lbs). In 2012 Annual Catch Limits were implemented (WPRFMC 2012).

This species is among the most extensively harvested lethrinids from reef flats in Guam and elsewhere (Taylor 2010). In Guam, Lethrinids are the largest component of the bottomfish fishery. The relative contribution of M. grandoculis is currently unknown. Catch-per-unit-effort has declined consistently from the early 1980s until 2008. From 2008 to 2010, CPUE (lbs/hr) values appear to be increasing; however, CPUE in 2010 is half that of the mid-late 1980s and early 1990s. High early CPUE values may be attributed to relatively unfished bottom areas being more productive. In Guam, Lethrinids have became rare on shallow reefs due to heavy fishing and possibly reef degradation due to natural and human impacts (Green et al. 1997). Emperors are frequently incidental catch in the fishery for small carangids. Coral reef fisheries around Guam have not been determined to be overfished, however, there are no existing stock assessments (WPRFMC 2012).

Commonwealth of Northern Mariana Islands (CNMI)
Lethrinids, which are caught using various methods, are the dominant catch in the CNMI, sometimes doubling or tripling the next most landed species. Fishing effort (number of boats and number of trips targeting bottomfish) has declined steadily from 2006 to 2011. Commercial landings of Lethrinids show large fluctuations from 1983 to 2011, and have fluctuated over the last 8 years. Catch-per-unit-effort (lbs per hour) has fluctuated from 2000 to 2011, with a slight decreasing trend. Bottomfish stocks are not experiencing overfishing although there are no species-specific stock assessments available (WPRFMC 2012).

The modal age of all samples of M. grandoculis, which indicates full recruitment to the common gear configuration used in Great Barrier Reef line fisheries, was three years, which corresponds to 20% of the estimated maximum age of 15 years. This species and other relatively large-bodied lethrinidae exhibited right-skewed frequency distributions. Very few specimens older than five years were sampled in the Great Barrier Reef (Currey et al. 2013). This species is a minor component of the Coral Reef Fin Fish Fishery in the Great Barrier Reef and is primarily taken by charter vessels rather than the commercial sector (Currey et al. 2010). Visual census among three mid-continental shelf reefs revealed significant temporal variation in the abundance of this species with counts being significantly higher in July than in September, February and May (Newman and Williams 2001).

Southeast Asia
In the Philippines, this species used to be locally abundant. However, it has been overexploited and now is not as common (K. Carpenter pers. comm. 2015).
Current Population Trend:Unknown
Additional data:

Habitat and Ecology [top]

Habitat and Ecology:Monotaxis grandoculis is usually found on coral reefs, often on the sandy periphery or in sand and rubble areas. Solitary individuals are often encountered, but large adults frequently form aggregations of up to about 50 individuals. The depths range of this species is between 3 and 60 m, although it appears to be most common between about 5 to 30 m. This species consumes mainly gastropod molluscs, ophiuroids and echinoids as well as pagurid and brachyuran crabs, polychaetes, tunicates and holothurians. It reaches a maximum size of 60 cm total length (TL); however, it is commonly seen to 40 cm TL (Carpenter 2001).

Use and Trade [top]

Use and Trade: This species caught mainly with gill nets, traps, spears and handlines. It is marketed fresh. Sometimes this species is ciguatoxic in the Marshall Islands (Carpenter 2001). Lethrinids are dominant features of fish landings in many parts of the Pacific. In Oceania, lethrinids are components of reef and lagoon and deep-slope species stocks, and are sometimes taken with small pelagics. Lethrinids are the main targeted reef fish species in Fiji. Commercial hand-line fishing primarily targets lethrinids in Guam in waters less than 150 m (Dalzell et al. 1996). Lethrinids are landed using hand-lines, spears, surrounding nets, and drive-in nets, and occasionally using spears and beach seines.

Threats [top]

Major Threat(s): This species is fished throughout its range, but this does not currently appear to be a major threat at the global level.

Conservation Actions [top]

Conservation Actions: There are no known species-specific conservation measures.

Citation: Carpenter, K.E., Lawrence, A. & Myers, R. 2016. Monotaxis grandoculis. The IUCN Red List of Threatened Species 2016: e.T16720607A16722460. . Downloaded on 16 October 2018.
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