| Red steenbras | |
|---|---|
 | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Acanthuriformes |
| Family: | Sparidae |
| Genus: | Petrus Smith, 1938 |
| Species: | P. rupestris |
| Binomial name | |
| Petrus rupestris (Valenciennes, 1830) | |
| Synonyms[2] | |
| |
Thered steenbras (Petrus rupestris) is aspecies of fish in the familySparidae and the only known member of themonospecific genusPetrus. This species isendemic to South Africa. The species' population has been depleted byoverfishing in African waters and it has been classified as an endangered species by theInternational Union for Conservation of Nature.
The red steenbras was first formallydescribed in 1830 asDentex rupestris by the FrenchzoologistAchille Valenciennes inHistoire naturelle des poissons which he wrote withGeorges Cuvier. Thetype locality was given as theCape of Good Hope.[3] In 1938 the South AfricanichthyologistJames Leonard Brierley Smith placesD. rupestris in a newmonospecific genus,Petrus.[4] This taxon is placed in the family Sparidae within theorderSpariformes by the 5th edition ofFishes of the World.[5] Some authorities classify this genus in the subfamily Denticinae,[6] but the 5th edition of Fishes of the World does not recognise subfamilies within the Sparidae.[5]
The red steenbras has the generic namePetrus which comes from theGreekpetra, meaning "rock", and is thought to be a reference to the rocky habitat preferred by this species. Thespecific name isrupestris, which means "dweller in rocks", again an allusion to this species rock habitat.[7]
The red steenbras has scales on the head that extend past the level of the eyes. The limbs of thegill rakers are both short. The bases of the soft rayed parted of the dorsal and anal fins are densely scaled. Thedorsal fin is supported by 10 spines and 10 or 11 soft rays while theanal fin has 3 spines and 8 soft rays. The body is elongate, compressed and moderately elongate and has a depth that first into itsstandard length 2.5 to 3 times. The dorsal profile of the head is almost straight between the snout and the origin of the dorsal fin in juveniles, becoming slightly convex as the fish grows. The front of the upper jaw has 4 robustcanine-like teeth while there are between 4 and 6 similar teeth on the front of the lower jaw, on each jaw there is a band of fine teeth behind the canine-like teeth.[8] The overall colour reddish, bronzy or golden-yellow with the young fish having a blotch to the rear of the dorsal fin. This is the largest species in the family Sparidae with a maximumtotal length of 200 cm (79 in), although 100 cm (39 in) is more typical, and a maximum published weight of 80 kg (180 lb).[2]
The red steenbras is endemic to South Africa where it occurs fromTable Bay in theWestern Cape toSt Lucia, KwaZulu-Natal. It is found at depths between 5 and 150 m (16 and 492 ft), with the adults found on offshore rocky reefs at depths greater than 50 m (160 ft) while the juveniles are found in shallower reefs.[1]
The red steenbras is a carnivore which feeds on octopuses, crabs and fishes,[8] especiallySpondyliosoma emarginatum.[2] This fish is a late maturinggonochorist, and is regarded as a rudimentary hermaphrodite, in that uit has both male and female reproductive tissue. It reaches sexual maturity at 7.2 years old and at an average total length of 63 cm (25 in) in both males and females. Thespawning season runs from August to October. SPawing seems to be confined to an area of sea betweenEast London and southern KwaZulu-Natal and also on the offshoreAgulhas Bank. They form spawning aggregations and the females have large ovaries which suggest that they are very fecund.[1]
The red steenbras was an important recreational and commercial fisheries target in South Africa but in 2012 a moratorium was placed on its fishing. It is a long lived and slowing maturing fish that undertake a northwards migration to off theEastern Cape to spawn. Here they were historically fished for by both recreational and commercial line fishermen. The life history traits shown by this species make it highly vulnerable to overfishing and make the recovery of the population very difficult. Illegal fishing, particularly targeting spawning schools, continues to pose a serious threat to this species and hold back the recovery of its population.[9] As the red steenbras is a long-lived, slow growing and late maturing species that has been overfished in the past and there has been no indication that the stock has recovered the International Union for Conservation of Nature have classified it asEndangered and state that it almost reaches the threshold of being classified asCritically Endangered, calling for research into the true status of the population and to measure the effectiveness of the moratorium on fishing.[1]
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