Lake Tanganyika sardine

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Lake Tanganyika sardine
Limio u0.gif
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Clupeiformes
Family: Dorosomatidae
Genus: Limnothrissa
Species:
L. miodon
Binomial name
Limnothrissa miodon
(Boulenger, 1906) [2]
Synonyms [3]
  • Pellonula miodonBoulenger, 1906

The Lake Tanganyika sardine (Limnothrissa miodon) is a species of freshwater ray-finned fish in the family Dorosomatidae which was endemic to Lake Tanganyika but which has now been introduced to other lakes in Africa as a food source. [2] It is one of two species within the genus Limnothrissa , the other being the Lake Mweru endemic, L. strappersi . This species and the Lake Tanganyika sprat are known collectively as kapenta.

Contents

Distribution

As its name suggests the Lake Tanganyika sardine was endemic to Lake Tanganyika extending into the lower reaches of the Malagarasi River. It was introduced to Lake Kivu in Rwanda in 1959 [4] and the man-made Lake Kariba in the Zambezi valley between Zambia and Zimbabwe, [1] and more recently into the Itezhi-Tezhi Dam in Zambia. [5] It has colonised Cahora Bassa lake in Mozambique from Lake Kariba - the fish have survived transit through the hydro-electric turbines in the Kariba Dam and made their way downstream, colonising Cahora Bassa. [5]

Description

A typical clupeiform, this is a small silver fish with a brighter stripe down the lateral line, a broad snout with tapering sides. It has a relatively large swim bladder which allows it to travel large vertical distances in the water column. [2] The maximum length is 17 centimetres (6.7 in), but most specimens are about 10 centimetres (3.9 in) long and they are thought to be sexually mature at 6.8 centimetres (2.7 in). [2]

Biology

Lake Tanganyika sardines undergo vertical migrations, spending the day in tight shoals in deep water, rising to the surface at dawn and dusk while spending the remainder of the night dispersed widely throughout the pelagic waters, although in Lake Kivu the fish move to the surface during the early morning and late afternoon. It is thought that these movements follow those of its food source, zooplankton but in Lake Kariba they do not. It seems that the fish and the plankton are responding to the same stimuli meaning that they occur in the same locations at similar times. One theory is that this may be a reaction to light intensity and be protection against predators, similar to that reported in marine clupeids. [5]

The depth used by Lake Tanganyika sardines is determined by the depth of the thermocline and the amount of dissolved oxygen. Below the thermocline, the water is normally anoxic and from November to April the fish are found no deeper than 20 metres (66 ft). Adults migrate into deeper water as they grow larger, with the smaller, young fish preferring clear water of around 1.5 metres (4 ft 11 in) deep with a rocky or sandy bottom and also occur in areas with steep shores. The adults move into the shallows to breed, [5] this is usually during the rainy season and peaks in May and June and again in December and January [2] but has been recorded throughout the year. [5] The fecundity of these fish increases as they grow; in samples from Lake Kariba a fish which was 46 millimetres (1.8 in) in length had 600 eggs while another measuring 11.4 centimetres (4.5 in) had 14,044 eggs. In Lake Tanganyika fish had higher fecundity and a fish sampled there of 140 millimetres (5.5 in) had 55,000 eggs. The main breeding season in Kariba is from about September to February, the population will generally increase steadily from February to August and then fall because of high mortality and decreased recruitment. [5]

Lake Tanganyika sardines are omnivorous, feeding mainly on zooplankton and phytoplankton. In Lake Kariba studies over time have shown that they opportunistically feed on the most abundant prey at any given time and different samples have shown the main prey to be Bosmina longirostris , Mesocyclops spp and Ceriodaphnia dubia . Lake Tanganyika sardines may have caused a decline in the abundance of some larger zooplankton species, e.g. Diaptomus , Ceriodaphnia and Diaphanosoma , which were more abundant in Lake Kariba prior to 1971 but as no stomach contents were sampled then we cannot be certain what caused their decline. [5] In Lake Tanganyika prey has been recorded as atyid shrimps, also copepods and prawns but larger fish have been known to prey on the larva of the Lake Tanganyika sprat. [2] Other food items include insects, such as chironomids, ephemeroptera, trichoptera and hemiptera and in some Lake Kariba samples these formed 55% of the stomach contents sampled and it is indicated by these samples that these prey items are taken on the surface at night. [5] In Lake Kivu cannibalism appears to be common and is suspected in the Lake Kariba population but these may also prey on other fish species, unidentified fish remains have been recorded in Kariba samples and a specimen of the Southern mouth-brooder Pseudocrenilabrus philander has been found in the stomach of 6.4 centimetres (2.5 in) specimen in Lake Kariba. [5]

Evolutionary History

Most clupeiforms are marine and Lake Tanganyika was formed by rifting and has never had a connection with sea, the family that the Lake Tanganyika sardine and its relative the Lake Tanganyika Sprat, are members of, the Dorosomatidae are common in southern and western Africa, for example Microthrissa royauxi [6] and Potamothrissa acuitirostris [7] in the Congo Basin. Molecular phylogenetic reconstructions indicate that the ancestors of these freshwater dorosomatids colonised West Africa 25–50 million years ago, at the end of a major marine incursion in the region. Dorosomatids subsequently speciated in an evolutionary radiation in West Africa, spreading across the continent and colonising Lake Tanganyika during its early formation. This shows that while Lake Tanganyika has never been directly connected with the sea, the endemic freshwater clupeiforms of the lake are descended from fish who radiated out of an ancient marine incursion. [8]

Etymology of the scientific name

The generic name is derived from the Greek limno meaning lake, referring to this species' distribution in Lake Tanganyika; and thrissa, the Greek word for a kind of anchovy which is used here as a standard suffix for clupeids, the specific name miodon is a compound of mio- meaning less or small and odon meaning tooth, referring to smaller teeth compared to related species such as Pellonula vorax . [9]

Predators

In Lake Kariba the most important predator on the Lake Tanganyika sardine is Hydrocynus vittatus , and the population in Lake Kariba increased following the introduction of the sardines. The diet of H. vittatus changed and as much as 70% of the food eaten by H. vittatus consisted of sardines by 1971. H. vittatus predation appears to be most intense at dawn and dusk when they were seen feeding on sardines at the surface at these times. [5]

Other fish predators of the sardines in Lake Kariba include Coptodon rendalli , Synodontis zambezensis and Schilbe intermedius . Some birds also feed on the sardines in Lake Kariba and possibly elsewhere, notably the white-winged black tern, Chlidonias leucoptera and the pied kingfisher Ceryle rudis. [5]

Fisheries

Kapenta rig Kariba Kapenta Rig.JPG
Kapenta rig

In Lake Kariba 360,000 [10] Lake Tanganyika sardines were introduced by the Zambian government [11] in 1967 and 1968 to be fished, here they enter the fishery at about 40 millimetres (1.6 in) in length when they are 3–4 months old. The bulk of those caught in the fishery are 40–50 millimetres (1.6–2.0 in) long and about 5 months old. There appears to be a correlation between biomass and fishing effort, as the biomass was 10% lower in 1985 than it was in 1974 when fishing began. [5] The annual catch on Lake Kariba is now between 20,000 and 30,000 tonnes (22,000 and 33,000 short tons). [11]

Kapenta fish drying in the sun Kapenta drying in the sun.jpg
Kapenta fish drying in the sun

See also

Related Research Articles

<span class="mw-page-title-main">Clupeiformes</span> Order of fishes

Clupeiformes is the order of ray-finned fish that includes the herring family, Clupeidae, and the anchovy family, Engraulidae. The group includes many of the most important forage and food fish.

<span class="mw-page-title-main">Lake Tanganyika</span> Rift lake in east-central Africa

Lake Tanganyika is an African Great Lake. It is the second-largest freshwater lake by volume and the second deepest, in both cases after Lake Baikal in Siberia. It is the world's longest freshwater lake. The lake is shared among four countries—Tanzania, the Democratic Republic of the Congo, Burundi, and Zambia—with Tanzania (46%) and the DRC (40%) possessing the majority of the lake. It drains into the Congo River system and ultimately into the Atlantic Ocean.

<span class="mw-page-title-main">Lake Kivu</span> Meromictic lake in the East African Rift valley

Lake Kivu is one of the African Great Lakes. It lies on the border between the Democratic Republic of the Congo and Rwanda, and is in the Albertine Rift, the western branch of the East African Rift. Lake Kivu empties into the Ruzizi River, which flows southwards into Lake Tanganyika. In 1894, German officer and colonial ruler Gustav Adolf von Götzen was the first European to discover the lake.

Kariba is a resort town in Mashonaland West province, Zimbabwe, located close to the Kariba Dam at the north-eastern end of Lake Kariba, near the Zambian border. According to the 2022 Population Census, the town had a population of 27,600.

<span class="mw-page-title-main">Lake Kariba</span> Reservoir in Zimbabwe

Lake Kariba is the world's largest artificial lake and reservoir by volume. It lies 1,300 kilometres (810 mi) upstream from the mouth of the Zambezi river on the Indian Ocean, along the border between Zambia and Zimbabwe. Lake Kariba was filled between 1958 and 1963 following the completion of the Kariba Dam at its northeastern end, flooding the Kariba Gorge on the Zambezi River.

<span class="mw-page-title-main">Kapenta</span>

The Tanganyika sardine is a term for two related species, both of which are small, planktivorous, pelagic, freshwater clupeid originating from Lake Tanganyika in Zambia. They form the major biomass of pelagic fish in Lake Tanganyika and Lake Malawi, swimming in large schools in the open lake, feeding on copepods and potentially jellyfish. Their major predators are four species of Lates which are also endemic to Lake Tanganyika, and are related to the Nile perch in Lake Victoria. All of these pelagic fish have suffered from overfishing in the last two decades.

<span class="mw-page-title-main">Sprat</span> Common name for several kinds of forage fish

Sprat is the common name applied to a group of forage fish belonging to the genus Sprattus in the family Clupeidae. The term also is applied to a number of other small sprat-like forage fish. Like most forage fishes, sprats are highly active, small, oily fish. They travel in large schools with other fish and swim continuously throughout the day.

Tigerfish can refer to fish from various families, and derives from official and colloquial associations of these with the tiger. However, the primary species designated by the name "tigerfish" are African and belong to the family Alestidae.

<i>Bathybates</i> Genus of fishes

Bathybates is a genus of piscivorous cichlids endemic to Lake Tanganyika in East Africa. The genus includes both pelagic species that mainly feed on Tanganyika sardines and benthic species that mainly feed on other cichlids. They are some of the deepest-living cichlids, regularly occurring down to 200 m (660 ft).

Chelaethiops minutus is a species of ray-finned fish in the family Cyprinidae. It is endemic to Lake Tanganyika and its outflow, the Lukuga River and is found in Burundi, Democratic Republic of the Congo, Tanzania, and Zambia.

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

The Lake Malawi sardine, lake sardine, or usipa, is an African species of freshwater fish in the family Cyprinidae. It is endemic to Lake Malawi and its outlet, the (upper) Shire River; it is found in Malawi, Mozambique, and Tanzania.

The silver cyprinid also known as the Lake Victoria sardine, mukene, and omena, dagaa (Swahili) is a species of pelagic, freshwater ray-finned fish in the carp family, Cyprinidae from East Africa. It is the only member of the genus Rastrineobola.

<i>Diplotaxodon limnothrissa</i> Species of fish

Diplotaxodon limnothrissa is a species of haplochromine cichlid which is endemic to Lake Malawi and it is found in Malawi, Mozambique, and Tanzania. It occurs in inshore and offshore waters, on reefs and over the rock shelf; and it is abundant over the anoxic zone. It is a maternal mouthbrooder and it feeds on zooplankton. It is probably the most abundant species of cichlid in Lake Malawi. The specific name references the clupeid Limnothrissa miodon, the Lake Tanganyika sardine, to which this species bears some morphological and biological similarities.

<i>Limnothrissa</i>

Limnothrissa is a small genus of freshwater ray-finned fishes elonging to the family Dorosomatidae, which also includes the gizzard shads and sardinellas. The species in this genus are endemic to Africa. It was considered to be monospecific but L. strappersi, a Lake Mweru endemic, has been recognised as a valid species. The Lake Tanganyika sardine was endemic to Lake Tanganyika but has been introduced to Lake Kivu, Lake Kariba and the Cahora Bassa reservoir.

The Lake Tanganyika sprat is a species of fish in the family Dorosomatidae. It is monotypic within the genus Stolothrissa. It is found in Burundi, the Democratic Republic of the Congo, Tanzania, and Zambia. Its natural habitat is freshwater lakes. It and the Lake Tanganyika sardine are known collectively as kapenta.

<span class="mw-page-title-main">Forage fish</span> Small prey fish

Forage fish, also called prey fish or bait fish, are small pelagic fish that feed on planktons and other small aquatic organisms. They are in turn preyed upon by various predators including larger fish, seabirds and marine mammals, this making them keystone species in their aquatic ecosystems.

The West African pygmy herring is a very small fish, reaching a maximum length of 3 centimetres (1.2 in) SL. It is a member of the clupeiform family Dorosomatidae in the freshwater systems of western and central Africa that includes such species as the Microthrissa royauxi of the Congo River basin and Limnothrissa miodon of Lake Tanganyika. It is the only species of its genus.

<i>Hydrocynus vittatus</i> Predatory freshwater fish

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<i>Microthrissa royauxi</i> Species of fish

Microthrissa royauxi, the royal sprat, is a species of pelagic, freshwater fish from the herring family Clupeidae which is found in the Congo River basin in west Africa. It was described in 1902 by the Belgian-British zoologist George Albert Boulenger. It is of limited importance as a food fish in subsistence fisheries and its conservation status is Least Concern.

Ndagala or Daaga are the vernacular names given to two species of small pelagic fish of the Clupeidae family, which are only found in Lake Tanganyika.

References

  1. 1 2 Rachel ndlovu (2006). "Limnothrissa miodon". IUCN Red List of Threatened Species . 2006: e.T60754A12406200. doi: 10.2305/IUCN.UK.2006.RLTS.T60754A12406200.en . Retrieved 16 November 2021.
  2. 1 2 3 4 5 6 "Limnothrissa miodon (Boulenger, 1906) Lake Tanganyika sardine". fishbase.org. Retrieved 20 August 2016.
  3. ↑ Eschmeyer, William N.; Fricke, Ron & van der Laan, Richard (eds.). "Species in the genus Limnothrissa". Catalog of Fishes . California Academy of Sciences . Retrieved 22 November 2024.
  4. ↑ Collart, Alphonse (June 1989). "Introduction et acclimatation de l'Isambaza du lac Tanganyika au lac Kivu". Compte rendu du seminaire trente ans apres l'introduction de l'Isambaza au lac Kivu (RWA/87/012/DOC/TR/16) (in French). Gisenyi, Rwanda: Food and Agriculture Organization of the United Nations.
  5. 1 2 3 4 5 6 7 8 9 10 11 12 Chifamba, P.C. (1992) The Life History of Limnothrissa miodon in Lake Kariba. Papers presented at the Symposium on Biology, Stock Assessment and Exploitation of Small Peleagic Fish Species in the African Great Lakes Region. Kariba, Zimbabwe: Lake Kariba Fisheries Research Institute.
  6. ↑ "Microthrissa royauxi Boulenger, 1902 Royal sprat". fishbase.org. Retrieved 20 August 2016.
  7. ↑ "Potamothrissa acutirostris (Boulenger, 1899) Sharpnosed sawtooth pellonuline". fishbase.org. Retrieved 20 August 2016.
  8. ↑ Wilson, Anthony B.; Teugels, Guy G.; Meyer, Axel (2008). "Marine Incursion: The Freshwater Herring of Lake Tanganyika Are the Product of a Marine Invasion into West Africa". PLOS ONE. 3 (4): e1979. Bibcode:2008PLoSO...3.1979W. doi: 10.1371/journal.pone.0001979 . PMC   2292254 . PMID   18431469.
  9. ↑ "Order CLUPEIFORMES (part 2 of 2)". The ETYFish Project. Christopher Scharpf and Kenneth J. Lazara. Retrieved 4 October 2016.
  10. ↑ Kefasi, Nyikahadzoi. "Heterogeneity and Rule Conformance in the Management of the Kapenta Fishery at Lake Kariba, Zimbabwe". Research Gate.
  11. 1 2 Madamombe, Loveless (2002). The economic development of the Kapenta fishery Lake Kariba (Zimbabwe/Zambia) (PDF) (MSc thesis). Norwegian College of Fishery Science.
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