Blacksaddled coral grouper (Plectropomus laevis)
|Also known as:||Saddleback coralgrouper|
|Synonyms:||Bodianus cyclostomus, Bodianus melanoleucos, Bodianus melanoleucus, Labrus laevis, Paracanthistius melanoleucus, Paracantistius maculatus, Plectropoma maculatum, Plectropoma melanoleucum, Plectropomus leopardus, Plectropomus maculates, Plectropomus maculatum melanoleucum, Plectropomus melanoleucus|
|Size||Length: up to 125 cm (1)|
|Weight||18 kg (1)|
Classified as Vulnerable (VU) on the IUCN Red List (1).
Like other groupers, this rather wary (2), coral reef-dwelling fish is a large, robust species (2) (3). It may be one of two colour forms: the pale black-saddled form is whitish or pale yellowish, with five dark brown to black bars on the head and body. Small blue spots with dark edges may also pattern the body. The other colour form is much darker, being brown, olive, red, or nearly black, speckled with numerous, dark-edged blue spots. The dark bars that appear on the pale form are either very faint or entirely absent in this form (3). Blacksaddled coral groupers have large mouths, lined with numerous small teeth and prominent canines on the sides of the lower jaw, enabling them to be efficient predators of other reef inhabitants (2).
The blacksaddled coral grouper occurs in the Indo-Pacific. From the east African coast, its distribution stretches east to French Polynesia in the central and southern Pacific, and extends as far north as Japan (1) (3).
As its name suggests, this grouper inhabits coral reefs, between depths of 4 and 90 metres (3), where it is said to be encountered most frequently in channels (2).
Typically found hovering just above the bottom (2), this large grouper is one of the major predators within its coral reef habitat (3), feeding on a range of large fish, including other grouper species and crustaceans. Its tendency to feed on large fish explains why high concentrations of ciguatoxin may be found in this species (1).
Like many groupers, this species has a fascinating life history. All blacksaddled groupers begin life as a female, and then as the animal ages, based on internal or external triggers, it shifts sex to become a male animal, a system known as protogynous hermaphroditism (3).
Most groupers are solitary fish, except when it comes to spawning (3), when small groups or larger aggregations form to release large quantities of eggs into the surrounding water (1). The eggs are fertilised by sperm released by males into the water, and after a period, the round, floating eggs hatch to reveal a tiny larva. The blacksaddled grouper is a fairly fast-growing species, with females reaching maturity in less than three years (1). Groupers typically spawn as a female for one or more years, before changing sex and then functioning as a male (3).
This Vulnerable fish is thought to be threatened by collection for the aquarium trade. It is also occasionally caught for food, despite the danger of ciguatera poisoning, and while this is not currently believed to pose a threat, there is potential for hunting for human consumption to increase and have an impact on the blacksaddled grouper (1).
The blacksaddled coral grouper occurs in a number of protected areas throughout its range, as well as being subject to several conservation actions in certain areas (1). For example, in the Great Barrier Reef Marine Park, 30 percent of the area is closed entirely to fishing, while in the remainder of the park, blacksaddled coral groupers below 50 centimetres are not allowed to be caught (1). In Pohnpei, Micronesia, a ban on the sale of this species and other groupers is in place during March and April (1), presumably to protect this species during the critical spawning period.
For further information on the conservation of groupers see:
Grouper and Wrasse Specialist Group:
Society for the Conservation of Reef Fish Aggregations:
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- Ciguatoxin: a substance produced in some tiny marine organisms. The toxin accumulates in the flesh of certain fish, as the microorganisms are eaten by small fish, which in turn are eaten by larger fish. Humans who eat fish containing ciguatoxin may get ciguatera poisoning, developing nausea, vomiting, numbness of parts of the body and even coma.
- Crustaceans: diverse group of arthropods (a phylum of animals with jointed limbs and a hard chitinous exoskeleton) characterised by the possession of two pairs of antennae, one pair of mandibles (parts of the mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, slaters, woodlice and barnacles.
- Larva: stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
- Spawning: the production or depositing of large quantities of eggs in water.
IUCN Red List (April, 2008)
- Lieske, E. and Myers, R. (2001) Coral Reef Fishes. HarperCollins Publishers, London.
- Heemstra, P.C. and Randall, J.E. (1993) FAO Species Catalogue. Volume 16: Groupers of the World. FAO, Rome.