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Epinephelus diacanthus 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Actinopterygii Perciformes Epinephelidae

Scientific Name: Epinephelus diacanthus (Valenciennes, 1828)
Common Name(s):
English Spinycheek Grouper
French Mérou Épineux
Spanish Mero Espinudo
Synonym(s):
Epinephelus dayi (Bleeker, 1874)
Epinephelus diacanthus (Valenciennes, 1828)
Serranus diacanthus (Valenciennes, 1828)
Serranus sexfasciatus (non Valenciennes)
Taxonomic Notes: Records of E. diacanthus from the western Pacific are based on misidentifications of E. stictus (Heemstra and Randall 1993). Records of E. diacanthus from South Africa are misidentifications of E. rivulatus (Heemstra and Randall 1993).

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2008
Date Assessed: 2008-01-01
Assessor(s): Sadovy, Y., Pollard, D., Russell, B. & Heemstra, P.C.
Reviewer(s): Sadovy, Y. & Moss, K. (Grouper and Wrasse Red List Authority)
Justification:
Epinephelus diacanthus is listed as Near Threatened. Population decline (A4d) over much of its range inferred from expanding trawl fisheries into deeper water and apparent overexploitation of juveniles and adults in shallower water. Also vulnerable to net fisheries because of aggregating behavior and insufficient management. More up to date information on its abundance, biology, age-and-growth and management practices is recommended before it disappears due to unsustainable exploitation (especially the trawling fishery).

Geographic Range [top]

Range Description:General
Epinephelus diacanthus is an Indian Ocean species found on the continental shelf of the northern Indian Ocean from the Gulf of Aden (possibly) to Sri Lanka and Madras (India). It is not known from the Persian Gulf nor the Red Sea (Heemstra and Randall 1993). Western Indian Ocean (30°E to 80°E; 45°S to 30°N), Eastern Indian Ocean (77°E to 150°E; 55°S to 24°N). Records of Epinephelus diacanthus from the South China Sea, southern East China Sea, and western Pacific (Chen et al. 1997) are based on misidentifications of E. stictus (Heemstra and Randall 1993).

Specific
India, Iran, Oman, Pakistan, Sri Lanka, Yemen and Iraq (Nader and Jawdat 1977). The species is also possibly found off Malaysia and Mozambique.
Countries occurrence:
Native:
Djibouti; India; Iran, Islamic Republic of; Oman; Pakistan; Sri Lanka; United Arab Emirates; Yemen
FAO Marine Fishing Areas:
Native:
Indian Ocean – western; Indian Ocean – eastern
Additional data:
Lower depth limit (metres):500
Upper depth limit (metres):10
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Fisheries-dependent data
It is uncommon in Sri Lanka, but abundant on muddy trawling grounds and forms large schools on Pakistan trawling grounds at depths of 20 to 50 m (Debruin et al. 1995). There have been declines noted in India and some concern that juveniles were being taken. One of the most abundant species in trawl catches (18 to 45 m) (James et al. 1996). See Table 1 in the Supplementary Material, showing the mortality, yield and stock parameters for E. diacanthus (Chakraborty 1994).

India
The landing of E. diacanthus at Mangalore increased by 328% from 81.4 tonnes in1988/89 to 348.3 tonnes in 1993/94, with an increase in catch rate (kg / hour) from 0.18 to 0.54, respectively (Zacharia et al. 1995a). E. diacanthus was found in the trawl fishery from October to May, with peak landing occurred during December (Zacharia et al. 1995a).

See Table 2 showing the annual landings of E. diacanthus and ‘all fish’ catch by multi-day trawlers at Mangalore and Malpe during 1988/89 to 1993/94 (Zacharia et al. 1995a) in the Supplementary Material.

In September 1995, E. diacanthus comprised 82.65% (size ranged from 25 to 46 cm TL with modal size group at 30 to 34 cm TL) of the groupers caught in the trawl fishery in India. In October 1995, the size of fish dropped to a length range of 20 to 32 cm TL with modal size at 24 to 26 cm TL (Zacharia et al. 1995b).

Pakistan
Based on a trawl survey carried out off Pakistan waters in 1983-1984, the mean catch rates of E. diacanthus ranged 6.80 kg/hour in September to 12.68 kg/hour in June (Iqbal 1995).

Biomasses of E. diacanthus in Pakistani coastal waters and in total shelf area of Sindh were estimated ranging from 0.01 to 0.14 tonnes per nm² and 93 to 1302 tonnes per nm², respectively (Iqbal 1995).

Fisheries-independent data
Epinephelus diacanthus is moderately common in northwest India in visual surveys (Sluka and Lazarus in press).
For further information about this species, see 132777_Epinephelus_diacanthus.pdf.
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Current Population Trend:Decreasing
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:General
Epinephelus diacanthus occurs on mud or muddy sand bottom in depths of 10 to 120 m (Heemstra and Randall 1993). It occurs within trawl catches ranging in India from 250 to 500 m (cited in James et al. 1996). Also recorded on hard coral and hard bottom in shallow water (2 to 12 m) (possibly juvenile habitat?) (Sluka and Lazarus in press). Epinephelus diacanthus reaches 52 cm TL (Boulenger 1895).

Feeding
Based on 65 specimens collected in India, Epinephelus diacanthus feeds on crustaceans (mainly crabs and small prawns) and fishes (mainly Ambassis sp. and Leiognathus spp.) (Zacharia et al. 1995a).

Juveniles abound the midshelf waters for feeding for eight months before migrating to the deeper waters for further growth and breeding (Zacharia et al. 1995a).

Reproduction, age, growth and maturity
Maturity
Based on 530 specimens collected in 2000-2001 in Oman, 87.2% and 71.7% of the fish sampled were mature females and males, respectively (McIlwain et al. 2003). In Oman, sizes of first maturity for female and male E. diacanthus were found to be 39.2 mm FL and 42.5 mm FL, respectively (McIlwain et al. 2003).

The minimum size of maturity was estimated to be about 125 mm SL in Taiwan (Chen et al. 1980b).

Spawning
According to GSI study, McIlwain et al. (2003) found that spawning of female Epinephelus diacanthus coincided with the decrease in sea surface temperature (25°C to 22.3°C) during June and July, during which disappearance of spawning / running gonads were also seen from macroscopic examinations. But there was no such pattern for male Epinephelus diacanthus (McIlwain et al. 2003).

Growth
Zacharia et al. (1995a) calculated that the growth rate of juvenile is 2.5 cm per month. Based on fish collected in Greater Bombay in 1989 to 1992, the length-at-age von Bertalanffy growth equation for Epinephelus diacanthus (sample size not specified) was found to be TL=502 mm (1-e(-0.61(Age-0)) (Chakraborty 1994).

Based on 5,043 specimens collected at two landing centers of Greater Bombay in India, Chakraborty and Vidyasagar (1996) calculated the length-at-age von Bertalanffy growth equation for E. diacanthus to be TL=494 mm (1-e(-0.59(t-t0/)).

Mortality
The natural mortality of Epinephelus diacanthus was calculated to be 1.10 in India (Chakraborty and Vidyasagar 1996).

Sexual pattern
Based on 380 specimens collected in 1975 to 1977 in Taiwan, E. diacanthus is protogynous which changes sex at two to three years of age in Taiwan (Chen et al 1980b). Chen et al. (1980b) found that the intersexual fish were found within two to six year-old classes and absent during spawning, and males became dominant after four years old.

Fecundity and Recruitment
Chen et al. (1980b) estimated the fecundity of E. diacanthus ranged from 64,000 to 233,000 ova, with a linear relationship with SL (Fecundity = -265.2036+2.6570xSL).

Sex ratio
Based on 530 specimens collected in 2000 to 2001 in Oman, the male-to-female sex ratio of Epinephelus diacanthus was found to be 1:2.3, with females (40.3 mm FL; Flmin-max: 26.0-53.2 mm FL) had a lower average body size than males (41.2 mm FL; Flmin-max: 28.2 to 51.6 mm FL) (McIlwain et al. 2003).

More up-to-date information on its abundance, biology, age-and-growth and management practices is recommended given its susceptibility to probable unsustainable exploitation (especially the trawling fishery).
Systems:Marine

Threats [top]

Major Threat(s): General
The greatest threat to Epinephelus diacanthus is overfishing and exploitation of juveniles and possible bycatch from trawl fisheries.

Fisheries-dependent
Zacharia et al. (1995a) indicated that very small E. diacanthus were discarded as trash fish and used for poultry feed. The trawl fishery of E. diacanthus consisted exclusively of juveniles (max catch size was 23.5 cm TL) from 30 to 60 m depth, which comprised of the 0-year age class (Zacharia et al. 1995a). The trawling fishery went deeper from 60 to 80 m in 1994 to 72 to 108 m in 1996, inducing a more serious threat to the population in Indian waters (Zacharia et al. 1995b).

Exploitation of juveniles and the associated overfishing will lead to depletion of the stock of E. diacanthus from Dakshina Kannada coast in India (Zacharia et al. 1995a).

Chakraborty (1994) suggested go fishing beyond 70 m in Bombay waters will increase the yield of E. diacanthus without posing a threat to the depletion of this species On the contrary, Zacharia et al. (1995b) pointed out that the trawling fishery went deeper from 60 to 80 m in 1994 to 72 to 108 m in 1996 will inducing a more serious threat to the population in the Indian waters.

McIlwain et al. (2003) suggested area closures that protecting critical habitat together with installing satellite tracking devices in individual trawlers would be successful in managing this species.

Conservation Actions [top]

Conservation Actions: No specific conservative measures for Epinephelus diacanthus.

McIlwain et al. (2003) suggested area closures that protecting critical habitat together with installing satellite tracking devices in individual trawlers would be successful in managing this species.

Citation: Sadovy, Y., Pollard, D., Russell, B. & Heemstra, P.C. 2008. Epinephelus diacanthus. The IUCN Red List of Threatened Species 2008: e.T132777A3448896. . Downloaded on 21 September 2018.
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