Sawfin
Encyclopedia
The Sawfin also known as Clanwilliam Sawfin, is a ray-finned fish species
in the family
Cyprinidae. It is placed in the "wastebin genus" Barbus
– the typical barbels and relatives – by default. But actually it is far less closely related to the typical barbels than to the South Africa
n redfins in Pseudobarbus
, and may well belong in the latter genus. Like Pseudobarbus but unlike most other Africa
n "barbs", it is tetraploid. Its closest living relative is probably the Cape Whitefish
(B. andrewi).
This sizeable cyprinid
can grow to over 40 cm (15.7 in) long and weigh more than 3 kg (6.6 lb).
, where it was formerly widespread in the Olifants River and its tributaries. Its range has decreased throughout most of the 20th century, and by now it is apparently only found in the upper Olifants River as well as the Biedou, Doring
, Driehoeks, Jan Dissels, Oorlogskloof, Ratels and Tra Tra Rivers.
It is rather euryoecious, inhabiting a wide variety of small and large rivers. While young fish are common in pools in the foothills, adults will move further down to where the rivers enter the coastal plain
and the water is deeper. The Sawfin is omnivorous, but mainly eats aquatic
insect
s and their larva
e. Its breeding season runs from late spring to summer (October to December), when schools of adults form to migrate upriver to shallow riffle
s with cobble
ground, where they spawn
. This species
is long-lived and slow-growing, with yearling
s being about 10 cm (3.9 in) long. It is only half-grown at about 4 years of age, and can get more than 10 years old.
(Micropterus dolomieu), which can kill off antire subpopulations by eating the juveniles. Clanwilliam Yellowfish
(Labeobarbus capensis) might be regarded as a competitor for food, but this is apparently not significant. Other threats are water pollution
and overuse, mainly due to agriculture
. Overall however, its stocks are healthy wherever the Smallmouth Bass is absent, but this still restricts its range quite a lot.
It is also listed as Endangered by the Nature Conservation Ordinance of Western Cape Province. For the time being, it may not be killed or caught. Considerable populations are found in the Cederberg Wilderness Area, Matjies River Nature Reserve and Oorlogskloof Nature Reserve. In 2004, the Greater Cederberg Biodiversity Corridor was established by CapeNature
and private landowners to better preserve and develop high-quality habitat
. This project aims at restoring the river ecosystems for sustainable development
. The Sawfin has been bred in captivity
at the Clanwilliam Yellowfish conservation station, but captive breeding success is not sufficient and improved techniques are needed.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Cyprinidae. It is placed in the "wastebin genus" Barbus
Barbus
Barbus is a ray-finned fish genus in the family Cyprinidae. The type species of Barbus is the Common Barbel, first described as Cyprinus barbus and now named Barbus barbus...
– the typical barbels and relatives – by default. But actually it is far less closely related to the typical barbels than to the South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
n redfins in Pseudobarbus
Pseudobarbus
Pseudobarbus is a ray-finned fish genus in the family Cyprinidae. The type species is Burchell's Redfin . The scientific name is derived from the Ancient Greek pseudes and the Latin word barbus . This genus contains some of the South African redfins...
, and may well belong in the latter genus. Like Pseudobarbus but unlike most other Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
n "barbs", it is tetraploid. Its closest living relative is probably the Cape Whitefish
Cape Whitefish
The Cape Whitefish or Berg-breede River Whitefish is a ray-finned fish species in the family Cyprinidae. It is placed in the "wastebin genus" Barbus – the typical barbels and relatives – by default...
(B. andrewi).
This sizeable cyprinid
Cyprinid
The family Cyprinidae, from the Ancient Greek kyprînos , consists of the carps, the true minnows, and their relatives . Commonly called the carp family or the minnow family, its members are also known as cyprinids...
can grow to over 40 cm (15.7 in) long and weigh more than 3 kg (6.6 lb).
Distribution and ecology
It is endemic to the Western Cape Province of South AfricaSouth Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
, where it was formerly widespread in the Olifants River and its tributaries. Its range has decreased throughout most of the 20th century, and by now it is apparently only found in the upper Olifants River as well as the Biedou, Doring
Doring River
Doring River, The Doring River originates northeast of Ceres and joins the Olifants River near the towns of Klawer and Vredendal, Western Cape, South Africa...
, Driehoeks, Jan Dissels, Oorlogskloof, Ratels and Tra Tra Rivers.
It is rather euryoecious, inhabiting a wide variety of small and large rivers. While young fish are common in pools in the foothills, adults will move further down to where the rivers enter the coastal plain
Coastal plain
A coastal plain is an area of flat, low-lying land adjacent to a seacoast and separated from the interior by other features. One of the world's longest coastal plains is located in eastern South America. The southwestern coastal plain of North America is notable for its species diversity...
and the water is deeper. The Sawfin is omnivorous, but mainly eats aquatic
Aquatic animal
An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...
insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s and their larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e. Its breeding season runs from late spring to summer (October to December), when schools of adults form to migrate upriver to shallow riffle
Riffle
A Riffle is a short, relatively shallow and coarse-bedded length of stream over which the stream flows at higher velocity and higher turbulence than it normally does in comparison to a pool....
s with cobble
Cobble (geology)
A cobble is a clast of rock with a particle size of to based on the Krumbein phi scale of sedimentology. Cobbles are generally considered to be larger than pebbles and smaller than boulders . A rock made predominantly of cobbles is termed a conglomerate....
ground, where they spawn
Spawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...
. This species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
is long-lived and slow-growing, with yearling
Yearling
Yearling may refer to:*Yearling , an animal in its second year of life.**Yearling , a horse between one and two years of age.in titles or proper names:*Yearling Books, an imprint of the publishing company Random House....
s being about 10 cm (3.9 in) long. It is only half-grown at about 4 years of age, and can get more than 10 years old.
Status and conservation
This species is considered Endangered by the IUCN, as it has declined much between the 1930s and 1970s. This seems to have been mainly due to the introduced Smallmouth BassSmallmouth bass
The smallmouth bass is a species of freshwater fish in the sunfish family of the order Perciformes. It is the type species of its genus...
(Micropterus dolomieu), which can kill off antire subpopulations by eating the juveniles. Clanwilliam Yellowfish
Clanwilliam Yellowfish
The Clanwilliam Yellowfish is a ray-finned fish species in the family Cyprinidae. It has long been placed in Barbus, the "wastebin genus" for barbs, by default; however, the species is increasingly being restored to related yellowfish genus Labeobarbus which seems a much more appropriate placement...
(Labeobarbus capensis) might be regarded as a competitor for food, but this is apparently not significant. Other threats are water pollution
Water pollution
Water pollution is the contamination of water bodies . Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful compounds....
and overuse, mainly due to agriculture
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...
. Overall however, its stocks are healthy wherever the Smallmouth Bass is absent, but this still restricts its range quite a lot.
It is also listed as Endangered by the Nature Conservation Ordinance of Western Cape Province. For the time being, it may not be killed or caught. Considerable populations are found in the Cederberg Wilderness Area, Matjies River Nature Reserve and Oorlogskloof Nature Reserve. In 2004, the Greater Cederberg Biodiversity Corridor was established by CapeNature
CapeNature
CapeNature is a governmental organisation responsible for maintaining wilderness areas and public nature reserves in Western Cape Province, South Africa.-West Coast:*Cederberg Wilderness Area...
and private landowners to better preserve and develop high-quality habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
. This project aims at restoring the river ecosystems for sustainable development
Sustainable development
Sustainable development is a pattern of resource use, that aims to meet human needs while preserving the environment so that these needs can be met not only in the present, but also for generations to come...
. The Sawfin has been bred in captivity
Captive breeding
Captive breedingis the process of breeding animals in human controlled environments with restricted settings, such as wildlife reserves, zoos and other conservation facilities; sometimes the process is construed to include release of individual organisms to the wild, when there is sufficient...
at the Clanwilliam Yellowfish conservation station, but captive breeding success is not sufficient and improved techniques are needed.