Oreochromis mortimeri

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Oreochromis mortimeri
Oreochromis mortimeri.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Cichliformes
Family: Cichlidae
Genus: Oreochromis
Species:
O. mortimeri
Binomial name
Oreochromis mortimeri
(Trevawas, 1966)
Synonyms
  • Tilapia mortimeriTrewavas, 1966
  • Sarotherodon mortimeri(Trewavas, 1966)

Oreochromis mortimeri, the Kariba tilapia or kurper bream, is a species of cichlid, formerly classified as a Tilapiine cichlid but now placed in the genus Oreochromis , the type genus of the tribe Oreochromini of the subfamily Pseudocrenilabrinae. It is found in the rivers of south central Africa especially the middle Zambezi where it is endangered by the spread of invasive congener Oreochromis niloticus .

Contents

Description

Oreochromis mortimeri is greenish grey, green-blue or grey-blue marked with darker spots on each of its scales. The females and immature males often have 1–3 dark blotches in the middle of their flanks although these may only be visible as the fish dies. The breeding males are mainly iridescent, shading from blue-green to bronze and they have iridescent spots on their dorsal and caudal fins. The dorsal fin has a red margin that is not as obvious as it is in O. mossambicus , with a thin red band at posterior end of caudal fin, whereas that of O. mossambicus is noticeably wider. The jaws of mature males are obviously enlarged. [2]

Distribution

Oreochromis mortimeri is endemic to the middle Zambezi valley form the Cahora Bassa gorge to the Victoria Falls. [1] Its distribution includes the Luangwa River and its tributaries. [2] It occurs in Mozambique, Zimbabwe and Zambia. [1]

Biology

Oreochromis mortimeri is a schooling species which is predominantly diurnal. It is also tolerant of higher salinities. Its diet largely consists of filamentous algae and diatoms, and also includes some vascular plants, Dipteran larvae, other insects, cladocerans, copepods, shrimps, annelids and molluscs. [2]

The male makes a saucer-shaped depression with a raised mound in the middle as a nest situated within a breeding arena in water less than 4 metres (13 ft) in depth. The male attracts the females to the arena using a courtship display. The female lays the eggs and they are fertilised by the male before she collects them in her mouth. The mouthbrooding females do not feed and may form shoals. The eggs hatch after around ten days but the larvae remain in their mother's mouth for a few more days. Once the yolk has been consumed the fry undertake brief feeding sorties, staying close to their mother and darting into her mouth when threatened. Around a fortnight after hatching the female releases the 1 centimetre (0.39 in) young fish in nursery areas of warm shallow water close to the banks, where the young fish group in small shoals in which they forage independently. The female then goes back to the breeding arena where she spawns again. [2] Breeding occurs throughout the year. [1]

Conservation

The IUCN classify O. mortimeri as Critically Endangered and the main threat to this species is the invasive Oreochromis niloticus which has been introduced into most of the range of O. mortimeri by aquaculture and by anglers. [1] Studies in Lake Kariba have shown that O. niloticus has higher growth rates than O.mortmeri and this is inferred to be a competitive advantage for the invasive species. [3] It was also found that O. niloticus is more aggressive towards O. mortimeri and that the larger the size of individual O. niloticus then the more aggressive it was to smaller specimens of O. mortimeri, the higher growth rates of the invasive species meaning that they were normally the larger individuals. [4] The nature of the distribution of O. mortimeri means that there are no natural impediments to O. niloticus spreading throughout its range and it has already displaced the native species in much of Lake Kariba, especially in areas where there are fish farms rearing O. niloticus, [5] a practice which began in the 1990s. [6]

Etymology

The specific name of this fish honours M. A. E. Mortimer who was a Research and Administrative Officer of the Zambian Department of Game and Fisheries and who studied the Tilapiine fishes of Zambia as well as arranging for Ethelwynn Trewavas to take a trip to the Luangwa Valley to study this fish in its natural habitat. [7]

Related Research Articles

<span class="mw-page-title-main">Cichlid</span> Family of fishes

Cichlids are fish from the family Cichlidae in the order Cichliformes. Cichlids were traditionally classed in a suborder, the Labroidei, along with the wrasses (Labridae), in the order Perciformes, but molecular studies have contradicted this grouping. On the basis of fossil evidence, it first appeared in Tanzania during the Eocene epoch, about 46–45 million years ago. The closest living relative of cichlids is probably the convict blenny, and both families are classified in the 5th edition of Fishes of the World as the two families in the Cichliformes, part of the subseries Ovalentaria. This family is large, diverse, and widely dispersed. At least 1,650 species have been scientifically described, making it one of the largest vertebrate families. New species are discovered annually, and many species remain undescribed. The actual number of species is therefore unknown, with estimates varying between 2,000 and 3,000.

<span class="mw-page-title-main">Tilapia</span> Common name for many species of fish

Tilapia is the common name for nearly a hundred species of cichlid fish from the coelotilapine, coptodonine, heterotilapine, oreochromine, pelmatolapiine, and tilapiine tribes, with the economically most important species placed in the Coptodonini and Oreochromini. Tilapia are mainly freshwater fish inhabiting shallow streams, ponds, rivers, and lakes, and less commonly found living in brackish water. Historically, they have been of major importance in artisanal fishing in Africa, and they are of increasing importance in aquaculture and aquaponics. Tilapia can become a problematic invasive species in new warm-water habitats such as Australia, whether deliberately or accidentally introduced, but generally not in temperate climates due to their inability to survive in cold water.

<span class="mw-page-title-main">Mouthbrooder</span> Animal that cares for its offspring by holding them its mouth

Mouthbrooding, also known as oral incubation and buccal incubation, is the care given by some groups of animals to their offspring by holding them in the mouth of the parent for extended periods of time. Although mouthbrooding is performed by a variety of different animals, such as the Darwin's frog, fish are by far the most diverse mouthbrooders. Mouthbrooding has evolved independently in several different families of fish.

The Wami tilapia is a tilapiine cichlid that grows to over 20 cm in length and is considered a useful food fish in Tanzania and the island of Zanzibar, where it may have been introduced by man. It is tolerant of brackish water and grows well in saline pools, making it particularly suitable for aquaculture by communities living close to the sea. Like other tilapia it is an omnivore and will feed on algae, plants, small invertebrates, and detritus. The common name refers to the Wami River.

<span class="mw-page-title-main">Nile tilapia</span> Species of fish

The Nile tilapia is a species of tilapia, a cichlid fish native to parts of Africa and the Levant, particularly Israel and Lebanon. Numerous introduced populations exist outside its natural range. It is also commercially known as mango fish, nilotica, or boulti.

<i>Oreochromis</i> Genus of fishes

Oreochromis is a large genus of oreochromine cichlids, fishes endemic to Africa and the Middle East. A few species from this genus have been introduced far outside their native range and are important in aquaculture. Many others have very small ranges; some are seriously threatened, and O. ismailiaensis and O. lidole possibly are extinct. Although Oreochromis primarily are freshwater fish of rivers, lakes and similar habitats, several species can also thrive in brackish waters and some even survive in hypersaline conditions with a salinity that far surpasses that of seawater. In addition to overfishing and habitat loss, some of the more localized species are threatened by the introduction of other, more widespread Oreochromis species into their ranges. This is because they—in addition to competing for the local resources—often are able to hybridize.

<span class="mw-page-title-main">Tilapiine cichlid</span> Tribe of fishes

The Tilapiini are a tribe within the family Cichlidae commonly known as tilapiine cichlids. Formerly this tribe contained many other genera and species, including the economically important Oreochromis and Sarotherodon, but a taxonomic review found that this grouping was paraphyletic and most were moved to Coelotilapini, Coptodonini, Heterotilapini, Oreochromini and Pelmatolapiini. Together, most species in these tribes are called "tilapias". In a more distant past, a number of other, more different genera like Steatocranus also were included in Tilapiini. With these as separate, Tilapiini now is a much more restricted tribe with only three genera and about half a dozen species from Central and Southern Africa.

<span class="mw-page-title-main">Aquaculture of tilapia</span> Third most important fish in aquaculture after carp and salmon

Tilapia has become the third most important fish in aquaculture after carp and salmon; worldwide production exceeded 1.5 million metric tons in 2002 and increases annually. Because of their high protein content, large size, rapid growth, and palatability, a number of coptodonine and oreochromine cichlids—specifically, various species of Coptodon, Oreochromis, and Sarotherodon—are the focus of major aquaculture efforts.

Throughout much of the tropics, tilapiine cichlids native to Africa and the Levant have been widely introduced into a variety of aquatic systems. In the U.S. states of Florida and Texas, tilapia were originally introduced to curtail invasive plants. In an effort to meet the growing demand for tilapia, humans have farmed these fish in countries around the world. Capable of establishing themselves into new ponds and waterways, many tilapia have escaped aquaculture facilities across much of Asia, Africa, and South America. In other cases, tilapia have been established into new aquatic habitats via aquarists or ornamental fish farmers.

<span class="mw-page-title-main">Mozambique tilapia</span> Species of fish

The Mozambique tilapia is an oreochromine cichlid fish native to southeastern Africa. Dull colored, the Mozambique tilapia often lives up to a decade in its native habitats. It is a popular fish for aquaculture. Due to human introductions, it is now found in many tropical and subtropical habitats around the globe, where it can become an invasive species because of its robust nature. These same features make it a good species for aquaculture because it readily adapts to new situations. It is known as black tilapia in Colombia and as blue kurper in South Africa.

Aristochromis christyi is a species of fish in the family Cichlidae, which is endemic to Lake Malawi in Africa. It is the only known member of its genus.

<i>Oreochromis amphimelas</i> Species of fish

Oreochromis amphimelas is a species of tilapia cichlid endemic to north–central Tanzania, where it is found in Lake Manyara and a number of other saline lakes with closed basins. Maximum recorded size is 28 cm (11 in) in standard length.

<span class="mw-page-title-main">Lake Chala tilapia</span> Species of fish

The Lake Chala tilapia is a species of cichlid fish that is endemic to Lake Chala, a small crater lake on the border of Kenya and Rombo District of Kilimanjaro Region in Tanzania. It mostly lives in relatively deep water, at depths between 20–45 m (66–148 ft). It is considered critically endangered by the IUCN, with the two primary threats being deterioration of its habitat due to siltation, and other non-native tilapia species that have been introduced to Lake Chala. Before these introductions, the Lake Chala tilapia was the only fish in Lake Chala. It is very closely related to the similar Jipe tilapia, another highly threatened species from the same general region of Kenya and Tanzania. The Lake Chala tilapia can reach a standard length of up to 30 cm (12 in).

<i>Oreochromis leucostictus</i> Species of fish

Oreochromis leucostictus is a species of cichlid native to Albertine Rift Valley lakes and associated rivers in DR Congo and Uganda. It has now been introduced widely elsewhere East Africa, and is believed to have negative ecological impact, particularly on native tilapias. This species is reported to reach a standard length of up to 36.3 cm (14.3 in), but is usually much smaller. It is exploited by small-scale fishery and aquaculture operations.

<i>Oreochromis lidole</i> Species of fish

Oreochromis lidole is a species of freshwater fish in the family Cichlidae. This tilapia is native to Malawi, Mozambique and Tanzania, where it is found in Lake Malawi, Lake Malombe, the Shire River and perhaps some crater lakes further north. It is important in fisheries, but has drastically declined; it may already be extinct. This oreochromine cichlid is locally called chambo, a name also used for two other closely related species found in the same region, O. karongae and O. squamipinnis.

<i>Oreochromis variabilis</i> Species of fish

Oreochromis variabilis, the Victoria tilapia, is a species of African cichlid native to Lake Victoria and its tributaries, Lake Kyoga, Lake Kwania, and Lake Bisina (Salisbury), as well as being found in the Victoria Nile above Murchison Falls. This species can reach a standard length of 30 cm (12 in). This species is important to local commercial fisheries and is potentially important in aquaculture. It is also found in the aquarium trade.

<i>Tristramella</i> Genus of fishes

Tristramella is a genus of oreochromines, freshwater fishes in the cichlid family. The members of this genus prefer standing waters and their native range is restricted to the Jordan River system, including Lake Tiberias (Kinneret), in Israel and Syria, with introduced populations in a few other places in Syria. Its members are among the few cichlids native to Western Asia, the others being Astatotilapia flaviijosephi, Coptodon zillii, Iranocichla, Oreochromis aureus, O. niloticus and Sarotherodon galilaeus.

<i>Oreochromis andersonii</i> Species of fish

Oreochromis andersonii, the three-spotted tilapia, threespot tilapia, or threespot bream, is a species of cichlid native to Africa, where it is found in rivers and swamps in the southern half of the continent. This species reaches a length of 61 cm (24 in). It is important to local commercial fisheries, as well as being commercially farmed. It is also popular as a gamefish. The identity of the person honoured in the specific name of this fish is not known but it is though most likely to be the Swedish explorer and hunter Charles John Andersson (1827-1867) who explored much of Namibia where the type was collected.

The Wami tilapia or Rufiji tilapia is a species tilapiine cichlid that is native to Morogoro Region of Tanzania. It is an important food fish and has been introduced to several other countries, although most of these populations possibly are hybrids with close relatives, especially Mozambique and Nile tilapia.

<span class="mw-page-title-main">Oreochromini</span> Tribe of fishes

Oreochromini is a tribe of cichlids in the Pseudocrenilabrinae subfamily that is native to Africa and Western Asia, but a few species have been widely introduced to other parts of the world. It was formerly considered to be part of the tribe Tilapiini but more recent workers have found that the Tilapiini sensu lato is paraphyletic. Despite this change, species in Oreochromini are still referred to by the common name tilapia and some of the most important tilapia in aquaculture —certain species of Oreochromis and Sarotherodon— are part of this tribe. In contrast, several species have small ranges and are seriously threatened; a few are already extinct or possibly extinct.

References

  1. 1 2 3 4 5 Marshall, B.E.; Tweddle, D. (2007). "Oreochromis mortimeri". IUCN Red List of Threatened Species . 2007: e.T63337A12659594. doi: 10.2305/IUCN.UK.2007.RLTS.T63337A12659594.en . Retrieved 20 November 2021.
  2. 1 2 3 4 Froese, Rainer; Pauly, Daniel (eds.) (2018). "Oreochromis mortimeri" in FishBase . October 2018 version.
  3. Portia Chifamba & John J. Videler (2014). "Growth rates of alien Oreochromis niloticus and indigenous Oreochromis mortmeri in Lake Kariba, Zimbabwe". African Journal of Aquatic Science. 2014 (2): 1–10. Abstract.
  4. Portia Chiyedza Chifamba & Tendai Mauru (2017). "Comparative aggression and dominance of Oreochromis niloticus (Linnaeus, 1758) and Oreochromis mortimeri (Trewavas, 1966) from paired contest in aquaria". Hydrobiologia. 788 (1): 193–203. doi:10.1007/s10750-016-2997-y.
  5. Will Darwall; D. Tweddle; K. Smith; P. Skelton (2009). The Status and Distribution of Freshwater Biodiversity in Southern Africa. IUCN red list of threatened species: Regional assessment. IUCN. p. 32. ISBN   978-2831711263.
  6. Tsungai A. Zengeya; Anthony J. Booth & Christian T. Chimimba (2015). "Broad Niche Overlap between Invasive Nile Tilapia Oreochromis niloticus and Indigenous Congenerics in Southern Africa: Should We be Concerned?". Entropy. 17 (7): 4959–4973. doi: 10.3390/e17074959 .
  7. Christopher Scharpf & Kenneth J. Lazara (4 December 2018). "Order CICHLIFORMES: Family CICHLIDAE: Subfamily PSEUDOCRENILABRINAE (l-o)". The ETYFish Project Fish Name Etymology Database. Christopher Scharpf and Kenneth J. Lazara. Retrieved 8 February 2019.