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The humphead or Napoleon wrasse is one of the largest reef fishes in the world and is the largest member of the wrasse family (Labridae). The enormous size of adult fish is made even more imposing by the prominent hump that develops on their forehead, from which they earn their common name. Mature adults also have thick lips; juveniles can be identified by their pale greenish colour and two black lines running behind the eye.
The Humphead Wrasse is widely distributed on coral reefs and inshore habitats throughout much of the tropical Indo-Pacific, from western Indian Ocean and Red Sea to southern Japan, New Caledonia and into the central Pacific Ocean (follow link below for a distribution map). In Australia, it occurs on offshore reefs of north-western Australia and the Great Barrier Reef (Pogonoski et al. 2002). It is rare in the southern part of the Great Barrier Reef in the Capricorn-Bunker Group (Russell 1983) and at Middleton and Elizabeth Reef (Gill and Reader 1992). This species appears to occur predominantly at depths of less than 100 m. It is not known from the Hawaiian Islands, Johnston Island, Easter Island, Pitcairn Is., Rapa or Lord Howe Islands, Kermadec or Australes Is., and evidently does not occur in the Gulf of Oman, the Persian Gulf, Reunion Is., Mauritius or Rodrigues Is.
Adults are known to occur largely on outer reef areas, often in association with channels and passes. Spawning aggregation sites have been reported from outer reef areas.
In one study, small post-settlement humphead wrasses were found in a species of seagrass (Enhalys acoroides), four species of hard coral (three Acropora spp. and Porites cylindricus), and in the soft coral Sarcophyton sp. (branching form; M.A. Tupper, pers. comm.). After settlement, juveniles and adults live associated with reef or near-reef habitats of seagrass beds and mangrove areas, with juveniles typically inshore and the largest individuals found in deeper waters of outer reefs or lagoons (Myers 1999). Juveniles of 3–20 cm TL, and larger, occur in coral-rich areas of lagoon reefs, particularly among live thickets of staghorn, Acropora spp. corals, in seagrass beds, murky outer river areas with patch reefs, shallow sandy areas adjacent to coral reef lagoons, and mangrove and seagrass areas inshore (Randall 1955, Randallet al. 1978, Myers 1999, J.H. Choat, pers. comm.). Recruitment patterns may vary considerably between years (M.A. Tupper, unpublished data). Adults are more common offshore than inshore, their presumed preferred habitat being steep outer reef slopes, reef drop-offs, reef tops, channel slopes, reef passes, and lagoon reefs to at least 100 m. They are usually found in association with well-developed coral reefs (Vivien 1973, Randall et all. 1978, Winterbottom et al. 1989, Allen and Swainston 1992, Sluka 2000). Typically they are solitary or paired, but have also been noted in groups of 3–7 individuals (Donaldson 1995). They appear to be somewhat sedentary in that the same individuals, indentifiable by distinct natural markings, may be seen along the same stretch of reef for extended periods. Indeed, many commercial dive sites have their ‘resident’ Humphead Wrasse, a favoured species for divers. Natural densities are evidently never high, even in presumed preferred habitats. For example, in unfished or lightly fished areas, densities may range from two to rarely more than 10–20 individuals per 10,000 m² of suitable reef. In fished areas, however, densities are typically lower by tenfold or more, and in some places fish no longer appear to be present.
Accounts of reproductive activity in the field reveal that, depending on location, this species spawns between several and all months of the year, in small or large groupings, that spawning coincides with certain phases of the tidal cycle, and that groups of spawning fish can form daily, at a range of different reef types. Spawning areas and aggregated adults have been noted regularly along specific sections of reef, sometimes associated with no obvious topographical features, sometimes close to the shelf edge on outer reefs, or adjacent to exposed reef passes near fairly steep drop-offs, or on mid-shelf (unspecified) reefs (P.L. Colin, J.H. Choat, R. Hamilton, S. Oakley, pers. comms.). The species is evidently a daily spawner that probably does not migrate far to its spawning site(s), spawning for extended periods each year, i.e., a ‘resident’ spawner (Domeier and Colin 1997, P.L. Colin, pers. comm.): groups of up to 150 fish were observed in Palau along the shelf edge in a loose aggregation.
Probable spawning aggregations have also been noted on Australia’s Great Barrier Reef (GBR), Fiji, New Caledonia, and in the Solomon Islands. Although spawning was not always observed, aggregated fish were ripe, or exhibiting behaviour likely associated with spawning. On the GBR, aggregations of up to 10 large males and 20–50 smaller fish (35–95 cm TL) were noted (J.H. Choat, pers. comm.). GBR aggregations from the Ribbon Reefs and north of Jewell Reef, once noted to include hundreds of fish, are no longer known at the same sites (Johannes and Squire 1988, L. Squire, pers. comm.).
The longevity of this species is up to at least 32 years, with females outliving the males (the oldest female recorded was 32 years), and sexual maturity is reached at about eight years of age (Choat in Pogonosky et al. 2002). Histological studies show that sexual maturation is reached at a size of between 40 cm and 60 cm total length (Sadovy, unpublished data). This species is thought to be a protogynous hermaphrodite, with sex reversal occurring at about 15 years of age (Choat in Pogonosky et al. 2002). At a total length of approximately 111 cm (Lau and Li 2000). Males grow very rapidly (Choat in Pogonosky et al. 2002).
It feeds on a variety of molluscs, fishes, sea urchins, crustaceans and other invertebrates (Randall et al. 1997).
The Humphead Wrasse is widely distributed but is nowhere common, naturally. Densities rarely exceed 20 fish per hectare in the preferred habitats of outer reefs; more typically not more than 10. Wherever it is fished, even if only moderately, density quickly declines to 25% or less of peak densities recorded at no fishing – this is known from 24 different studies based on fishery-independent data from 11 range states (Sadovy et al. 2003). It appears to be extirpated from several edge of range locations (Sadovy et al. 2003). It is particularly heavily exploited (i.e., high levels of fishing pressure) at the centre of its range in southeastern Asia where its coral reef habitat is most abundant, and particularly in key supply countries for the live reef fish trade, Malaysia and Indonesia, and out of Palawan, its stronghold in the Philippines. In these countries all available fishery-dependent and trade-related data suggest declines over 10–15 years in exploited areas of 10–fold or more with fish now considered rare in areas where once it was common. Buyers of this fish are continually having to source new areas as numbers decline and the pattern of fishing reported is one typical of rapid serial depletions. Much of the capture in all major source countries for live fish are of small fish, mainly juveniles, according to all reliable accounts. Moreover, juveniles are the preferred size range for retailers of live Humphead Wrasse. Severe declines have also been noted nationally wherever the species is taken by speargun at night. Such is the concern for this species that it is one of the only reef fish protected by name (i.e., species name) across a range of countries. It is everywhere accessible to live fish catcher boats which can visit the most remote locations at will. Some spawning aggregations have been noted to decline or have disappeared in eastern Malaysia and Australia.
The total global catch of this species is estimated to be no more than 400 mt annually (Sadovy et al. 2003), yet despite this low volume, severe declines are noted in all places for which data are available and occurring very soon after fishing begins, reducing numbers by more than 50% (see country accounts and summary table) (both fishery-dependent and fishery-independent) and where management is not effective. Much of the trade is now in juvenile fish which is the preferred market size for live fish. It is severely reduced anywhere that it is fished unless a) it is effectively managed, b) there is no export trade or night spearfishing, and c) it is not included in marine protected areas. It is a species that appears to be highly conservation-dependent. There is no regional fishery management authority for this species and FAO does not collect data on it.
The listing of this species as Endangered is based on a population reduction of at least 50% over the last three generations (approximately 30 years) based on an index of abundance and actual or potential levels of exploitation (A2bd). The declines are predicted to continue or even accelerate because of the likely growth of the live fish export trade (A3bd).
This species can live at least 30 years (25 for males and 32 for females) and becomes sexually mature at six years (J.H. Choat, C.R. Davies, J. Ackerman and B.D. Mapstone, unpublished manuscript). This means that its generation time is expected to be in the order of 10 years and that the rate of intrinsic population increase is likely to be low; natural predators are few and natural mortality rate was determined to be 0.14 or less (J.H. Choat, C.R. Davies, J. Ackerman and B.D. Mapstone, unpublished manuscript). The species is particularly vulnerable because the bulk of the fishery for live fish, at least in east Malaysia, southwest Philippines and Indonesia (the major suppliers for the live reef fish trade and the centre of the species’ range) is selective for juvenile sized fish since this is the preferred size class for consumers and gains the highest prices. This selective fishery for animals below but close to the size of sexual maturation has the potential to severely reduce the reproductive capability of exploited populations. The species cannot be artificially cultured (i.e., hatchery produced) to relieve fishing pressure.
The declines are projected to continue or worsen in key source countries for live fish because:
a) The species is one of the two most highly valued fish, economically, in the luxury live reef fish trade on a per kg basis;
b) Of the probable intrinsic vulnerability of such a large and long-lived reef fish, that is also hermaphroditic with relatively few adult males, and an aggregation-spawner, to overfishing; and
c) In places where the species has declined but is still actively sought, fishers only find a few fish a month or a year, at most;
d) The projected growth in the live fish trade, especially into mainland China in the next few years.
Finally, despite regulations in many places, there is much illegal, unregulated and unmonitored trade, according to many verbal accounts by fishers and traders and there is no regional management authority actively engaged in managing this small fishery and FAO does not collect data on it. It only remains abundant where protected or not fished at all. Protective legislation in most places appears to be ineffective.
1) Intensive and species-specific removal for the live reef food fish export trade of a naturally uncommon and vulnerable species;
2) Readily accessible to spearfishing at night with SCUBA or hookah (i.e., compressed air) gear, and easy to catch with cyanide, or other poisons such as Derris trifoliata, due to predictable adult habitat and shallow depth range;
3) Lack of coordinated, consistent national and regional management largely due to limited management capacity and the sometime secretive nature of traders – in particular there is no relevant regional fishery management authority to address problems with this species;
4) Selective fishing, in particular the intensive take of juveniles for direct export sale and for grow-out (also referred to as ‘culture’ – the species cannot be hatchery reared; and
5) Illegal, unregulated, or unreported (IUU) fisheries (Donaldson and Sadovy 2001).
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