|Scientific Name:||Epinephelus awoara|
|Species Authority:||(Temminck & Schlegel, 1842)|
Epinephelus awoara (Temminck & Schlegel, 1842)
|Red List Category & Criteria:||Data Deficient ver 3.1|
|Assessor/s:||Shuk Man, C. & Ng Wai Chuen (Grouper & Wrasse Specialist Group)|
|Reviewer/s:||Cornish, A. & Sadovy, Y. (Grouper & Wrasse Red List Authority)|
Although the fishery for this species is not documented, it is known that fish of all sizes are captured; large juveniles and adults are offfered for sale both live and freshly dead ,and smaller fish for grow out in captivity. The species is also extensively cultured, both from wild-caught juveniles as well as from hatchery produced juveniles, according to reports from China. All groupers are popular for sale in SE Asia, especially alive, and the Yellow Grouper is one of the more common grouper species for sale in Hong Kong. Most of the fish sold in Hong Kong probably do not come from Hong Kong waters, however (Situ and Sadovy 2004) but from outside waters and from culture.
Mean market size in Hong Kong was found to be 155 mm (TL) in 1990s (Sadovy pers. comm. 1999) following a short study and 150–250 mm in 2004/5 following a more detailed study. Since E. awoara attains sexual maturation at size of 160 mm, and maximum size is 610, young fish are being removed from the fishery in substantial numbers and the fishery needs to be monitored.
Trade in adults and juveniles is unregulated and undocumented, although Hong Kong port surveys suggests about 9–10 tons were taken annually in recent years in local waters. In Malaysia, the only grouper term used is 'Epinephelus' (genus) with no distinction by species (Sadovy 2000). This classification is too broad to estimate the catch volumes, since trade volumes can reflect many things other than catch rates.
For such an important commercial species in South China, little is known of its biology or catch rates, more effort is needed to address both data gaps. Both fishery dependent and independent data are needed as well as an estimate of the contribution to sales of hatchery reared, as opposed to wild-caught, fishes.
Epinephelus awoara is a marine species that occurs in the northwestern Pacific Ocean, including North and South Korea, Japan, Taiwan, China, Viet Nam, and islands in the South China Sea (Heemstra and Randall 1993) and Indian Ocean (Chen 1997, Zhu 1998).
In China, E. awoara can be found in the South China Sea only, along the Guangdong coastline and Daya Bay (Institute of Oceanology Academia Sinica 1991).
E. awoara is rare in the coastal waters of the Pacific but very common in the Sea of Japan (Masuda et al. 1980), and south of Toyko (Nakabo 2000). In the sea of Japan it is known from Pusan, Toyama Bay, Niigata, and in the Sanin area. On the Pacific coast of Japan it occurs from Tokyo to Nagasaki and also around Ryukyu Island. It can be found all around Taiwan (Lindberg and Orlans 1967, Shao 2005).
The species is caught occasionally in Ha Long Bay and Me Island of Thanh Hoa province (central Viet Nam) (Sadovy 2000).
Native:China; Disputed Territory; Hong Kong; Japan; Korea, Democratic People's Republic of; Korea, Republic of; Philippines; Taiwan, Province of China; Viet Nam
|FAO Marine Fishing Areas:||
Pacific – northwest; Pacific – western central
|Range Map:||Click here to open the map viewer and explore range.|
An otter trawl survey conducted by Dr. Kwang-Tsao Shao around Taiwan (K.-T. Shao pers comm. 2004) showed that E. awoara was distributed from the 10 to 50 m depth off the Miaoli County, northwestern Taiwan. The density was 1.32 kg per square kilometer in this area. Nine of ten specimens were smaller than 100 g. The above density is an under estimate because the bottom trawl could not harvest in the reef areas which this species prefers to inhabit.
In Hong Kong, catch data were collected by a questionnaire survey with local fishermen in 1996/97; annual catch of E. awoara by weight was estimated to be 9 metric tons for all fishermen in all Hong Kong waters (AFD 1998); the survey was repeated in 2001/2002 and the annual catch was about 10.5 metric tons (AFCD 2004). About 30% of the local fishermen were interviewed and the total annual catch calculated by factoring up their responses.
The population status or abundance cannot be inferred from insufficient data.
Minimum population doubling time 4.5 to 14 years (Froese and Pauly 2005).
|Habitat and Ecology:||
E. awoara can be found in rocky areas and sandy-mud bottoms. Juveniles are common in tide pools and adults are caught in depths of 10–50 m. In captivity, E. awoara is an aggressive fish, spending much of its time chasing and biting other fishes, especially conspecifics (Heemstra and Randall 1993). It is very common in rocky areas and coral reefs in littoral or sublittoral area of Taiwan (Shen 1984).
E. awoara feeds on shrimp and other fishes (Zhu 1998). Massive E. awoara can be caught in Fujian annually between April and November and live fishes are sold to Hong Kong and Macau. E. awoara has the highest yield among Fujian groupers with high commercial value (Chu 1984). It is also a common commercial fish in Guangdong (China), Taiwan, and Japan.
In Hong Kong, E. awoara is categorized as moderately abundant (Sadovy and Cornish 2000). The fish is one of the four most common inter-tidal groupers in eastern Hong Kong waters, but in the field it is evidently not frequently seen (Sadovy and Cornish 2000).
The fish is cultured in both Hong Kong and Taiwan (Shao et al., 1996). Eggs of E. awoara have been artificially fertilized by Zhang and Li (1988) (as cited by Cheung 1998), and the longest survival time for the larvae was 15 days (Randall and Heemstra 1991).
E. awoara is protogynous, i.e. changes sex from female to male when they grow to certain size. Spawning season lasts from March to May in Hong Kong (Liu 1971) and June to July in Taiwan (Shao 2005). Size of sexual maturation is attained at 160 mm (TL), size at sex change 220–320 mm (TL), maximum size 610 mm (TL), while the mean market size is 155 mm (Y. Sadovy pers. comm. 1999).
Optimum water temperature for mature individuals to spawn is 23.2 to 23.4° C at salinity 20–34 ppt. E. awoara spawn in Taiwan from June to July during evening 6–8 pm. Fertilized eggs hatch after around 27 hours (Shao 2005).
E. awoara is a determinate spawner with a group-synchronous type of ovarian development pattern. Total annual potential fecundity was estimated to range from 55,200 to 1,146,400 oocytes for a fish of standard length from 161 to 315 mm. Relative fecundity was estimated to range from 432 oocytes to 1,017 oocytes, with body weight ranging from 136 g to 1,479 g. The minimum annual spawning frequency was two. Early yolked oocytes formed would probably be reabsorbed after spawning (Cheung 1998).
Potential annual fecundity of E. awoara exhibited a logarithmic relationship with standard length: F=22.95L2.84 where F is potential annual fecundity and L is standard length of E. awoara. A straight-line relationship was also found between potential annual fecundity and fish body weight. The regression equation of this relationship was found to be F= 733.14 W-37260 where F is potential annual fecundity and W is fresh body weight of E. awoara. There was no relationship between relative fecundity and either standard length or body weight (Cheung 1998).
Local market survey in Hong Kong (2004–2005) showed that live individuals of E. awoara sold in the market ranged from 400 mm, with the most common (70%) sizes from 150–250: most of the fish were reported caught from local waters (A. To pers. comm. 2005), although sources could not be determined and wet market data suggest that many E. awoara are not from local Hong Kong waters (Situ and Sadovy 1004). Of the 19 or so groupers sampled in the market, the Yellow Grouper was in the top third in terms of frequency of observation.
Data on size and age of sexual maturity and on fisheries landings outside Hong Kong, or from non-Hong Kong waters, are not available.
E. awoara is a valuable food fish, which is caught with trawl or hook-and-line (Heemstra and Randall 1993, Masuda et al. 1980).
Overfishing of grouper adults and juveniles, habitat damage and loss from bottom trawling, pollution, high demand for food are the main threats to E. awoara.
E. awoara occurs in the Cape d’Aguilar Marine Reserve (southeast Hong Kong island), and on no-take artificial reefs in Hong Kong, but these areas are likely to be too small to support viable reproductive populations (A. Cornish pers. comm. 2005), and the artificial reefs are still fished.
No species-specific management or conservation action has been taken.
From 1985/6, E. awoara seed was increasingly used and it has become the major species. However, in the last couple of years, less E. awoara is reported and traders suggest that this might be due to enforced closures of the South China Sea fishery (Sadovy 2000). During June and July each year, no trawling is permitted inshore in mainland Chinese waters (these do not include Hong Kong waters).
Large scale culture (grow out) of captured fry is taking place in South China, including Guangdong, Fujian and Zhejiang provinces, Hainan and Hong Kong, occasionally in Quang Ninh province, and in Viet Nam. It is an important species of wild seed caught in southern China (mainly Fujian and Xiamen). Some E. awoara seeds are/were also collected in Hong Kong in limited amounts (Sadovy 2000).
A hatchery in Zhejiang province reported production of E. awoara of at least 80,000 seeds per year and at a Daya Bay facility, NE of Hong Kong, there is active research on E. awoara with natural spawning in 1998. It is not known how much of the seed production comes from hatchery production or from the wild (grow out of wild-caught fish does not count as true mariculture since the juveniles still come form the wild and are, therefore, part of a juvenile fishery) (Sadovy and Lau 2002).
|Citation:||Shuk Man, C. & Ng Wai Chuen (Grouper & Wrasse Specialist Group) 2006. Epinephelus awoara. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 19 May 2013.|
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