General
Epinephelus tukula is a reef-associated species mainly found in deep reef channels and seamounts, in current prone areas. Juveniles may be found in tide pools. Considered to be exceedingly territorial and very aggressive towards intruders. Vulnerable to spear fishers. Hand fed by divers in certain areas, but potentially dangerous to the inexperienced. Prefers coral reefs, although also occurs on non-coral reefs at depths of 10 to 150 m (Heemstra and Randall 1986); museum specimens collected from 3 m depth on the GBR (Pogonoski et al. 2002), occasionally to depths of 400 m (QFS 2000, reported in Pogonoski et al. 2002). An aggressive species (van der Elst 1993), easily approached particularly on reefs which are protected from fishing.

Feeding
Feeds on reef fishes, skates, crabs, and spiny lobsters.

Growth and Reproduction
Maximum size 150 cm TL, 90 kg (Heemstra and Heemstra 2004); Lieske and Myers (1994) indicate a maximum length of 200 cm (110 kg). Yeh et al. (2003) reported inducing protogynous sex change in captive specimens. Matures at about 90 cm (Morgan, 1982); 90 cm TL/16 kg (Yeh et al. 2003); Lau and Li (2000) report maturity at 99 cm TL. Length weight relationship y(kg) = 1.0-5.xTL cm 3.07. A slow-growing species: von Bertalanffy parameters k 0.13 yr^-1, Linf 114.9 cm (t₀ assumed to be zero), natural mortality 0.13 yr^-1 (Grandcourt 2005). Ripe fish obtained in February, October and December on the central East African coast (North Kenya Banks and Mafia island; Nzioka 1977).

Red List Category

Red List Criteria

Year Assessed

Assessor/s

Reviewer/s

Contributor/s

General
Epinephelus tukula is not a common species where fishing is known to occur, but may be more common in unfished areas. The species is patchy over its range and highly localized. Very rare in Japan (Dr. A. Ebisawa, Okinawa Prefectural Fisheries and Ocean Research Center pers. comm.).

Fisheries-independent data
Potato grouper are classified as rare (based on density estimates) on the GBR (Pears 2005). Chater et al. (1993) recorded it as common during informal diving and angling surveys (8 to 45 m) on coral reefs in the St Lucia and Maputaland Marine Reserves (northern KwaZulu-Natal, South Africa) from 1987 to 1990. The St Lucia reserve, which is well-policed to prevent demersal fishing, had been in existence since 1979 at that point. In a more formal survey, in shallow (9 to 13 m) UVC surveys in these reserves between 1987 and 1992, Chater et al. (1995) recorded densities of this species which were higher than any other serranid. Attraction to divers cannot be ruled out however. On the west coast of India, this species was recorded at six of nine shallow water (2 to 28 m) sites surveyed in shallow water (2 to 28 m), but at a low relative abundance compared to other groupers (Sluka and Lazarus unpub.). Few seen in northern Somalia while diving on shallow (2 to 14 m) non-coral reefs in northern Somalia (Mann and Fielding 2000).

Fisheries-dependent data
Juveniles are relatively common (20% of all grouper caught from the shore by researchers, n=108 of 546 groupers) from the shore in the St Lucia/Maputaland marine reserves in South Africa 2000 to 2005; catches were higher in sanctuary areas compared to catches in areas which had been open to fishing five years previously (Mann, Oceanographic Research Institute, unpub. Data). Not reported from commercial line catches from southern Mozambique in the mid-1990s after the fishery rapidly developed following 20 years of light fishing effort owing to civil war (Dengo and David 1993, van der Elst et al. 1994). Recorded in 2002 to 2004 (no numbers provided) during monitoring of commercial linefish catches in southern/central Mozambique from 2000 to 2005 (D. Gove, Mozambican Fisheries Research Institute, pers. comm.); recorded in trap catches in central Mozambique from 1997 to 1998 (n=7 individuals of 1,304 groupers; Abdula et al. 2000). Morgans (1964) recorded only one individual in 689 groupers in catches on the North Kenya Banks, at a time when the reef had not been exploited. Nzioka (1977) recorded catching five specimens from 1974 to 1977 as part of a survey of reefs between Mafia Island (Tanzania) and the North Kenya Banks which caught 130 other serranid fishes. Also reported in catches from Reunion (D. Miossec, pers. comm. IFREMER) but lumped with several other species.

Reproduction
Localised small aggregations of large fish reported anecdotally by recreational scuba divers in numerous locations, particularly in areas where fishing effort is low e.g. northern KwaZulu-Natal MPAs, southern Mozambique – “Bass City” (Pereira 2003), Bassas d’India Mozambique channel (Oceanographic Research Institute, unpub. Data, Aldabra (Grandcourt 2005). Such aggregations may be for spawning as recorded by Robinson et al. (2004).

Unknown

General
Epinephelus tukula is threatened by loss of habitat and overfishing.

Loss of habitat
Episodes of coral reef bleaching in the range of this species are likely to occur increasingly as SST increases (Sheppard 2003). Dynamiting of reefs, fishing with poisons and netting on reefs have resulted in loss of habitat in several countries, such as Tanzania, Indonesia and Malaysia (Spalding et al. 2001, Kunzmann 2004).

Overfishing
Most of the fishing effort in the region is small-scale, is largely unregulated and can generally be assumed to be increasing (e.g. Martosubroto 2005, Cunningham and Bodiguel 2006, Morgan 2006, Flewelling and Hosch 2006). Caught in the live reef fish trade (Lee and Sadovy 1998). In the Hong Kong live fish markets.

General
Epinephelus tukula occurs in marine protected areas within its range.

Specific
Only 225 km² of reefs are no take-areas in Kenya, Tanzania and Mozambique (Wells et al. 2007) and it is no clear how much compliance there is. In KwaZulu-Natal in South Africa, most of the north coast which contains coral reefs is protected by a 145 km long MPA in which no demersal fishing is allowed, and is strictly enforced. It is intended that this MPA and the southern Mozambique coast from Ponta d’Ouro to Maputo will be incorporated into a Transboundary MPA, with areas zoned for protection, which will offer further protection to this species. May not be retained in South Africa (since 1992) and by recreational fishers in Mozambique (since 1999). Australia: Western Australia and Queensland: totally protected.