The red steenbras (''Petrus rupestris'') is a
species
A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
of fish in the family
Sparidae and the only known member of the
monospecific genus ''Petrus''. This species is
endemic
Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...
to South Africa. The species' population has been depleted by
overfishing
Overfishing is the removal of a species of fish (i.e. fishing) from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing Fish stocks, fish stock), resu ...
in African waters and it has been classified as an endangered species by the
International Union for Conservation of Nature
The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...
.
Taxonomy
The red steenbras was first formally
described in 1830 as ''Dentex rupestris'' by the French
zoologist
Zoology ( , ) is the scientific study of animals. Its studies include the structure, embryology, classification, habits, and distribution of all animals, both living and extinct, and how they interact with their ecosystems. Zoology is one ...
Achille Valenciennes in ''
Histoire naturelle des poissons'' which he wrote with
Georges Cuvier
Jean Léopold Nicolas Frédéric, baron Cuvier (23 August 1769 – 13 May 1832), known as Georges Cuvier (; ), was a French natural history, naturalist and zoology, zoologist, sometimes referred to as the "founding father of paleontology". Cuv ...
. The
type locality was given as the
Cape of Good Hope
The Cape of Good Hope ( ) is a rocky headland on the Atlantic Ocean, Atlantic coast of the Cape Peninsula in South Africa.
A List of common misconceptions#Geography, common misconception is that the Cape of Good Hope is the southern tip of Afri ...
.
In 1938 the South African
ichthyologist
Ichthyology is the branch of zoology devoted to the study of fish, including bony fish (Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 35,800 species of fish had been described as of March 2 ...
James Leonard Brierley Smith
James Leonard Brierley Smith (26 September 1897 – 8 January 1968) was a South African ichthyology, ichthyologist, organic chemist, and university professor. He was the first to identify a taxidermied fish as a coelacanth, at the time thought t ...
places ''D. rupestris'' in a new
monospecific genus, ''Petrus''.
This taxon is placed in the family Sparidae within the
order Spariformes by the 5th edition of ''
Fishes of the World''.
Some authorities classify this genus in the subfamily Denticinae,
but the 5th edition of Fishes of the World does not recognise subfamilies within the Sparidae.
[
]
Etymology
The red steenbras has the generic name ''Petrus'' which comes from the Greek ''petra'', meaning "rock", and is thought to be a reference to the rocky habitat preferred by this species. The specific name is ''rupestris'', which means "dweller in rocks", again an allusion to this species rock habitat.
Description
The red steenbras has scales on the head that extend past the level of the eyes. The limbs of the gill rakers are both short. The bases of the soft rayed parted of the dorsal and anal fins are densely scaled. The dorsal fin is supported by 10 spines and 10 or 11 soft rays while the anal fin
Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...
has 3 spines and 8 soft rays. The body is elongate, compressed and moderately elongate and has a depth that first into its standard length
Fish measurement is the measuring of individual fish and various parts of fish anatomy, their anatomies, for data used in many areas of ichthyology, including Taxonomy (biology), taxonomy and fishery biology.
Overall length
Standard length (SL) is ...
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 robust canine-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.[
]
Distribution and habitat
The red steenbras is endemic to South Africa where it occurs from Table Bay in the Western Cape to St Lucia, KwaZulu-Natal. It is found at depths between , with the adults found on offshore rocky reefs at depths greater than while the juveniles are found in shallower reefs.[
]
Biology
The red steenbras is a carnivore which feeds on octopuses, crabs and fishes,[ especially '' Spondyliosoma emarginatum''.][ This fish is a late maturing gonochorist, 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 in both males and females. The spawning season runs from August to October. SPawing seems to be confined to an area of sea between East London and southern KwaZulu-Natal and also on the offshore Agulhas Bank. They form spawning aggregations and the females have large ovaries which suggest that they are very fecund.][
]
Fisheries and conservation
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 the Eastern Cape
The Eastern Cape ( ; ) is one of the nine provinces of South Africa. Its capital is Bhisho, and its largest city is Gqeberha (Port Elizabeth). Due to its climate and nineteenth-century towns, it is a common location for tourists. It is also kno ...
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.Endangered
An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching, inv ...
and state that it almost reaches the threshold of being classified as Critically Endangered
An IUCN Red List critically endangered (CR or sometimes CE) species is one that has been categorized by the International Union for Conservation of Nature as facing an extremely high risk of extinction in the wild. As of December 2023, of t ...
, calling for research into the true status of the population and to measure the effectiveness of the moratorium on fishing.[
]
References
* G.D.Johnson, A.C.Gill, J.R.Paxton & W.N. Eschmeyer, ed. 1998. ''Encyclopedia of Fishes''. San Diego: Academic Press. .
* C.Michael Hogan. 2010
''Overfishing''. Encyclopedia of Earth. National Council for Science and the Environment
eds. Sidney Draggan and Cutler Cleveland. Washington DC.
External links
''Petrus rupestris'' on Fishbase
*
Sparidae
Fish described in 1830
Taxa named by Achille Valenciennes
{{Perciformes-stub