Fishing on Lake Victoria

Last updated
Fishing boats return laden with tilapia at Ggaba Landing Site, Uganda. Ugandan fishing boats.jpg
Fishing boats return laden with tilapia at Ggaba Landing Site, Uganda.

Lake Victoria supports Africa's largest inland fishery, with the majority of the catch being the invasive Nile perch, introduced in the Lake in the 1950s. [1]

Contents

History

The cichlid Haplochromis thereuterion is endemic to Lake Victoria. Haplochromis thereuterion.jpg
The cichlid Haplochromis thereuterion is endemic to Lake Victoria.

In 1927-1928 Michael Graham conducted the first ever systematic Fisheries Survey of Lake Victoria. The dominant species in the 1927–8 survey catches were two, now critically endangered tilapia species, the 'Ngege' or Singida tilapia (Oreochromis esculentus) and Victoria tilapia (O. variabilis). [2] [3] Other commonly observed species included: Marbled lungfish (Protopterus aethiopicus), Elephant-snout fish (Mormyrus kannume), Ripon barbel (Labeobarbus altianalis), African sharptooth catfish ( Clarias gariepinus ), silver butter catfish ( Schilbe intermedius ) and Semutundu (Bagrus docmak). The most common Haplochromis species were suggested to be Haplochromis guiarti and Haplochromis cinereus. [4]

In his official report of the survey, Graham wrote that "The ngege or satu Tilapia esculenta, is the most important food fish of the lake, whether for native or non-native consumption. No other fish equals it in the quality of the flesh. It is convenient size for trade, travels well and is found in much greater numbers than other important fish, such as semutundu (Luganda), Bagrus sp.''. [4] Furthermore, Graham noted that the introduction of the European flax gill-net of 5 inch mesh had undoubtedly caused a diminution in the number of ngege in those parts of the Kavirondo Gulf, the northern shore of the lake, the Sesse Islands and Smith's Sound that were conveniently situated close to markets. [4]

Before 1954, Lake Victoria's ecology was characterised by enormous biodiversity. It was inhabited by over 500 species of fish, 90% of which were cichlids belonging to the haplochromines. [5] They are thought to have evolved in Lake Victoria within the last 15,000 years. [6] [7] They are known for their extraordinary ability to evolve rapidly to suit extremely localised and diverse environments, a characteristic termed 'evolutionary plasticity'. [8] [9] [10] This ability has made the cichlid species of Lake Victoria an extremely successful fish. Haplochromine species accounted for some 80% of the fish biomass of the lake, [5] an abundance which led Graham to believe that this species flock could support a trawler fishery of up to 200 boats. [11] It also meant that Lake Victoria at one time boasted one of the most diverse fish environments on earth. [12] With such diversity, the cichlids of Lake Victoria managed to exploit virtually every food source available, including most detritus, zooplankton and phytoplankton. [8]

Haplochromine species are relatively small and bony, and were generally not favoured in catches. Riparian populations preferred the lake's two endemic species of tilapia ( Oreochromis esculentus and O. variabilis ). [Note 1] Hence, by the late 1940s, British colonial authorities were debating the overall ecological efficiency of the lake. For many authorities at this time, the lake needed a large and efficient predator to turn haplochromine fish stocks into something more economically valuable. The prime candidate was the Nile perch (Lates niloticus). Arguments in favour of introducing a predator were as follows:

  1. Evidence from other African lakes suggested that the Nile perch could do well commercially, and if the fish were introduced into Lake Victoria, it would no doubt eat the haplochromines, and hence improve the overall value of the fishery. In addition, it was suggested that by introducing such a fish, fishers might turn their attentions to catching it, so easing some of the pressure on tilapia stocks. [14] Because the Nile perch can weigh as much as 200 kilograms (440 lb), it was argued, fishers would be encouraged to use large mesh-sizes to capture it. [14] Furthermore, the perch was said to prefer off-shore habitats, and this would serve to relieve pressure on the in-shore tilapia fishery. [14] [15]
  2. In those lakes where the Nile perch was a native it co-existed with tilapia species, and therefore it posed no great danger to commercially important tilapia stocks in Lake Victoria. [14] [15]
  3. The potential size of the perch made it a fine sports fish, and this might attract sports fishers and tourists to the lake region. [15]
  4. Finally, archaeological findings close to Lake Victoria suggested that an ancestor of the Nile perch had been native to the Miocene predecessor of Lake Victoria, Lake Karunga. [16] It was reasoned, then, that if the perch had once been native to the lake, there was little reason why it could not be a native again. [15] [17]

The arguments against its introduction were as follows:

  1. Predators can never be as abundant as non-predators because of their nutritional requirements. In other words, the amount of fish a Nile perch has to eat to produce a kilogram of flesh is far greater than the amount of vegetative matter a tilapia has to eat to produce an equal amount of flesh. In ecological terms, the Nile perch is inefficient. [18] As mentioned above, the fertility of tropical waters depends on the rate at which nutrients (mainly detritus) are brought back into solution. The Nile perch, however, does not eat this detritus, and it was argued that its introduction would do little to improve the over-all ecological efficiency of the lake. If any fish should be introduced, it should be a herbivore or a detritivore. [19] [20]
  2. It would be wishful thinking to suppose that the Nile perch would exclusively consume haplochromines. [18]
  3. Given the complexity of tropical ecosystems, it is impossible to predict what might happen should the Nile perch be introduced. [18]

While the argument continued, it was agreed that tilapia stocks needed bolstering largely as a result of increasing fishing pressure on indigenous species, associated with the expansion of the market for fresh fish in the 1940s. [1] Tilapia introductions started in the early 1950s with Oreochromis leucostictus from Entebbe, and followed by Tilapia zillii (Winam Gulf, 1953), T. rendalli (Winam Gulf 1953–54), O. niloticus (Kagera River 1954) and O. mossambicus (Entebbe 1961–62). [12] [19] [21] [22] Because tilapia are detritivores and herbivores, these introductions were regarded as less threatening than the introduction of any carnivore. Nevertheless, while the argument over the introduction of the Nile perch raged throughout the early 1960s, it seems that it had already been surreptitiously introduced in 1954 from Uganda. [9] Once it had been discovered to be in the lake, further official introductions occurred in 1962 and 1963. [23]

Introduced tilapia species were unable to establish themselves in the lake between the 1950s and 1963. Following unusually heavy rainfall in the early 1960s, however (the so-called 'Uhuru Rains'), the lake-level rose considerably, flooding large areas of shore-line, and opening up new breeding areas to fledgling tilapia stocks, so creating the opportunities for these exotic species to compete with indigenous stocks. [1] Of the six exotic species introduced, two – Oreochromis niloticus and O. zillii – were to firmly establish themselves in the lake, so that by the early 1980s, these two species comprised the mainstay of tilapia catches. Of the indigenous species, O. esculentus was extirpated from the lake as a consequence of competition with introduced tilapiids, while O. variabilis populations declined significantly. [22]

The Nile perch is a substantial predator. One specimen, preserved at the Kisumu Museum in Kenya, weighed 184 kg (406 lb) when landed. Populations of the fish established themselves in a clockwise motion around the lake, starting in Uganda, followed by Kenya and ending in Tanzania. [5] Initial catches were minimal, but grew rapidly in the 1980s, heralding the start of the so-called 'Nile perch boom'. "On the face of it...the lake after the debut of Lates [Nile perch] has turned into a fish producer that can only be described in Gargantuan terms". [24]

The introduction of the Nile perch had a decisive impact on haplochromine stocks which it favoured as its prey, affecting both their abundance and diversity. It is believed that the contribution of this species flock to the fish biomass of the lake has decreased from 80% to less than 1% since the introduction of the Nile perch, [5] [25] and that some 40% of the haplochromine species were driven to extinction in the process. [26] [27] [28] This may well represent the largest extinction event amongst vertebrates in the 20th century [8] and has been called the "most dramatic example of human-caused extinctions within an ecosystem". [29]

Freed from their evolutionary predators, populations of the diminutive endemic silver cyprinid Rastrineobola argentea (omena in Luo, mukene in Ganda and dagaa in Swahili), flourished, developing into huge shoals. In turn, pied kingfisher (Ceryle rudis) populations, that had hitherto fed on haplochromines, exploded in response to this new food source. [30] Similar and other impacts have propagated throughout the ecosystem.

Given its 'evolutionary plasticity', it follows that haplochromines should adapt rapidly to the new environmental conditions generated by the Nile perch 'boom' and eutrophic conditions. Evidence from studies on the lake does suggest that this is happening. [31] One haplochromine, H. (Yssichromis) pyrrhocephalus , a zooplanktivore, was almost driven to extinction by the Nile perch. This species has recovered alongside increased exploitation of the Nile perch, at a time (the 1990s) when water clarity and dissolved oxygen levels had declined as a consequence of eutrophication. [32] Over a period of just two decades, H. pyrrhocephalus responded to raised hypoxia (oxygen deficiency) by increasing its gill surface area by 64%. Head length, eye length, and head volume decreased in size, whereas cheek depth increased. The former morphological changes may have occurred to accommodate this increased gill size. Other morphological changes suggest adaptations in response to the availability of larger and tougher prey types.

By the end of the 1940s, fish stocks were under severe pressure. The market for fish grew since railways were available to carry fish to the coast and settlements in between. Improved fishing boats and nets were introduced. [Note 2] [1] British colonial authorities set out to remedy this through the introduction of exotic species, including tilapia and the Nile perch. These introductions had five main impacts. The first of these was the rise of the Nile perch. The fish took some time to establish itself, and only began to appear in catch statistics in the mid-1970s. By the 1980s, the 'explosion' of this species was being referred to as the Nile perch 'boom'. Catches climbed from about 335 mt in 1975, to a peak of 380,776 mt in 1990. [Note 3] The second impact was the Nile perch's devastation of the haplochromine species flock, its main food source. Catches of this species crashed. The third impact related to the lake's diminutive endemic silver cyprinid, the dagaa. Freed from competition (with haplochromine species) for food sources, this species thrived. It was not the main target of the Nile perch, and catches increased spectacularly from 13,000 mt in 1975, to an all-time high 567,268 mt in 2006. The fourth main impact of the introductions related to the exotic tilapia species. One of these, the Nile tilapia (Oreochromis niloticus), was to establish itself firmly in the fishery. Tilapia catches from the lake rose from about 13,000 mt in 1975, to an all-time high of around 105,000 mt in 2000. There can be little doubt that these introductions saved the fishery from collapse. With such increases, so too the entire production system on the lake changed, the fifth and final key change. Prior to the arrival of the colonial administration, the fishery was dominated by fishermen (mainly, although certain fishing techniques were reserved for women) who owned their labour and their fishing gear. Contributing to the near-collapse of the fishery in the 1940s and 1950s was the reorganisation of the fishery into fleets drawing on hired labour and much improved gear. [1] [35] The Nile perch 'boom' was to accelerate and massively expand this process. It coincided with an emerging European market for high-quality white fish meat, prompting the development of industrial fish processing capacity along the lake's shores in Kisumu, Musoma, Mwanza, Entebbe and Jinja. [36] The export of Nile perch has since expanded away from the European Union (EU) to the Middle East, the United States and Australia, and now represents large foreign exchange earnings to the lake's riparian states. In Uganda, indeed, its export is second only to coffee in the rankings of export earnings. In 2006, the total value of Nile perch exports from the lake was estimated to be US$250 million. [37] The main market for the perch remains the EU, and the industry is, therefore, subject to the worries of EU health and safety inspectors. The EU has frequently closed its doors to the export for reasons ranging from unsatisfactory hygiene at factories to cholera outbreaks on the lake shores. [33]

In 2007, Lake Victoria Sailing Company (LVSC) petitioned the Ugandan government to gazette the first Lacustrine Protected Area (LPA) in Ugandan Lake Victoria that is enforced by the UPDF-Fish Protection Unit (FPU). This protected area is to encourage fishers to form fishing cooperatives and allow fish populations to replenish. [38]

In 2015, Victory Farms was founded by two Americans, and soon became the fastest growing fish farm in sub-Saharan Africa. [39]

Economic impact

With such high demands for Nile perch, the value of the fishery has risen considerably. Labour inflows into the fishery have increased along with growing demand. In 1983, there were an estimated 12,041 boats on the lake. By 2004, there were 51,712, and 153,066 fishermen. [34] The fishery also generates indirect employment for additional multitudes of fish processors, transporters, factory employees and others. All along the lakeshore, 'boom towns' have developed in response to the demands of fishing crews with money to spend from a day's fishing. [Note 4] These towns resemble shanties, and have little in the way of services. Of the 1,433 landing sites identified in the 2004 frame survey, just 20% had communal lavatory facilities, 4% were served by electricity and 6% were served by a potable water supply. [34]

The impact of perch fishing on the local economy is the subject of the 2004 documentary Darwin's Nightmare .

Controversy

The Nile perch fishery has proved controversial, not least between conservationists keen to see the preservation of the lake's unique ecology; and others who recognise the fish's importance to regional economies and poverty alleviation. In the 1990s, one group of thinkers argued that the export of this fish represented a net loss of fish proteins to riparian fishing communities, hence explaining high incidences of malnutrition amongst them. [41] [42] [43] 'Empirical evidence ... vividly show that the growing export of the Nile perch and the commercialisation of the dagaa are undermining the survival of households'. [44] Malnutrition amongst these communities are indeed high; one study estimates that 40.2% of children in fishing communities are stunted. [45] Rates of childhood malnutrition are, however, lower around the lake than they were in the agricultural hinterland. At fish landing sites, 5.7% of mothers were found to be chronically malnourished. [45]

The three countries bordering Lake Victoria – Uganda, Kenya and Tanzania – have agreed in principle to the idea of a tax on Nile perch exports, proceeds to be applied to various measures to benefit local communities and sustain the fishery. However, this tax has not been put into force, enforcement of fisheries and environmental laws generally are lax, and the Nile perch fishery remains in essence a mining operation so far.

Notes

  1. ↑ See for example Graham (1929) [11] and Beverton (1959). [13]
  2. ↑ A full description of the development of fish markets surrounding the Kenyan part of the lake is provided by Geheb, 1997. [1]
  3. ↑ See Geheb et al. (2008) [33] and catch statistics provided by the Lake Victoria Fisheries Organisation. [34]
  4. ↑ See for an anthropological study of these towns, called village landings, Beuving (2010). [40]

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. Traditionally Cichlids were 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">Lake Victoria</span> Lake in East-central Africa

Lake Victoria is one of the African Great Lakes. With a surface area of approximately 59,947 km2 (23,146 sq mi), Lake Victoria is Africa's largest lake by area, the world's largest tropical lake, and the world's second-largest fresh water lake by surface area after Lake Superior in North America. In terms of volume, Lake Victoria is the world's ninth-largest continental lake, containing about 2,424 km3 (1.965×109 acre⋅ft) of water. Lake Victoria occupies a shallow depression in Africa. The lake has an average depth of 40 m (130 ft) and a maximum depth of 80–81 m (262–266 ft). Its catchment area covers 169,858 km2 (65,583 sq mi). The lake has a shoreline of 7,142 km (4,438 mi) when digitized at the 1:25,000 level, with islands constituting 3.7% of this length.

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

The Nile perch, also known as the African snook, Goliath perch, African barramundi, Goliath barramundi, Giant lates or the Victoria perch, is a species of freshwater fish in family Latidae of order Perciformes. It is widespread throughout much of the Afrotropical realm, being native to the Congo, Nile, Senegal, Niger and Lake Chad, Volta, Lake Turkana, and other river basins. It also occurs in the brackish waters of Lake Maryut in Egypt. The Nile perch is a fish of substantial economic and food-security importance in East Africa. Originally described as Labrus niloticus, among the marine wrasses, the species has also been referred to as Centropomus niloticus. Common names include African snook, Victoria perch, and many local names in various African languages, such as the Luo name mbuta or mputa. In Tanzania, it is called sangara, sankara, or chenku. In Francophone African countries, it is known as capitaine. Its name in the Hausa language is giwan ruwa, meaning "water elephant".

<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">Lake Albert (Africa)</span> Lake in Uganda and the Democratic Republic of the Congo

Lake Albert, originally known as Lake Mwitanzige and temporarily Lake Mobutu Sese Seko, is a lake located in Uganda and the Democratic Republic of the Congo. It is Africa's seventh-largest lake, as well as the second biggest of Uganda's Great Lakes.

<span class="mw-page-title-main">Lake Kyoga</span> Large shallow lake in Uganda

Lake Kyoga or Lake Kioga is a large shallow lake in Uganda, about 1,720 km2 (660 sq mi) in area and at an elevation of 1,033 metres. The Victoria Nile flows through the lake on its way from Lake Victoria to Lake Albert. The main inflow from Lake Victoria is regulated by the Nalubaale Power Station in Jinja. Another source of water is the Mount Elgon region on the border between Uganda and Kenya. While Lake Kyoga is part of the African Great Lakes system, it is not itself considered a great lake.

<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">Haplochromine</span> Tribe of fishes

The haplochromine cichlids are a tribe of cichlids in subfamily Pseudocrenilabrinae called Haplochromini. This group includes the type genus (Haplochromis) plus a number of closely related genera such as Aulonocara, Astatotilapia, and Chilotilapia. They are endemic to eastern, southern and northern Africa, except for Astatotilapia flaviijosephi in the Middle East. A common name in a scientific context is East African cichlids – while they are not restricted to that region, they are the dominant Cichlidae there. This tribe was extensively studied by Ethelwynn Trewavas, who made major reviews in 1935 and 1989, at the beginning and at the end of her career in ichthyology. Even today, numerous new species are being described each year.

<i>Haplochromis</i> Genus of fishes

Haplochromis is a ray-finned fish genus in the family Cichlidae. It has been used as the default "wastebin taxon" for Pseudocrenilabrinae cichlids of the East African Rift, and as such became the "largest" fish "genus". Many of these cichlids are popular aquarium fishes; like similar Haplochromini they are known as "haplos", "happies" or "haps" among aquarium enthusiasts.

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>Oreochromis esculentus</i> Species of fish

Oreochromis esculentus, the Singida tilapia or Graham's tilapia, is a species of cichlid endemic to the Lake Victoria basin, including some of its satellite lakes such as Kyoga, in Tanzania, Uganda, and Kenya. Its common name refers to Lake Singida, but this population is the result of an introduction that happened in the 1950s. This fish is highly valued by local fishermen, who know it as ngege.

<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 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.

<span class="mw-page-title-main">Fishing industry in Uganda</span>

There are two major sources of fish in Uganda; one is from aquaculture, the other from fishing in rivers and lakes. The latter has made up the largest and most significant share of all fishing. Open water covers 15.3 percent of Uganda's surface and comprises five major lakes which are the main sources of fish in the country. Lake Victoria continues to be the most important water body in Uganda both in size and contribution to the total fish catch, followed by Lake Albert and Lake Kyoga.

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

The blue tilapia is a species of tilapia, a fish in the family Cichlidae. Native to Northern and Western Africa, and the Middle East, through introductions it is now also established elsewhere, including parts of the United States, where it has been declared an invasive species and has caused significant environmental damage. It is known as the blue kurper in South Africa.

Lake Nabugabo is a small freshwater lake in Uganda.

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

Lake Bisina, also known as Lake Salisbury, is a freshwater lake in eastern Uganda. It is a satellite lake of Lake Kyoga, which it drains into, and the two are to some extent directly connected by papyrus swamps. During the high-water rainy season, Lake Bisina can be up to 6 m (20 ft) deep and it is often directly connected to the smaller Lake Opeta, but during the dry season the two are clearly separated.

There are two major sources of fish in Uganda; one is from aquaculture, the other from fishing in rivers and lakes. Different types of fish flourish in different water sources. The waters of Uganda contain an impressive array of fish species—over 90 in all. This count does not include the Haplochromis complex, which itself is made up of more than 200 species.

<span class="mw-page-title-main">Fisheries Survey of Lake Victoria</span>

Lake Victoria supports Africa's largest inland fishery, with the majority of present catch being the invasive Nile perch, introduced to the Lake in the 1950s. Prior to the introduction of Nile perch as well as Nile tilapia, the fish community was very different and consisted mainly of 'Ngege' and Victoria tilapia as well as vast numbers of Haplochromis species. Fish communities in the first half of the 20th century are known primarily from a unique fisheries survey conducted in 1927-1928 by the Colonial Office.

References

  1. 1 2 3 4 5 6 Kim Geheb (1997). The Regulators and the regulated: fisheries management, options and dynamics in Kenya's Lake Victoria Fishery (Ph.D. thesis). University of Sussex. Archived from the original on 2011-10-07. Retrieved 2012-02-21.
  2. ↑ Twongo, T.K.; Bayona, J.D.R. & Hanssens, M. (2006). "Oreochromis esculentus". IUCN Red List of Threatened Species . 2006: e.T15457A4587658. doi: 10.2305/IUCN.UK.2006.RLTS.T15457A4587658.en . Retrieved 14 January 2018.
  3. ↑ Twongo, T.K.; Bayona, J.D.R. & Hanssens, M. (2006). "Oreochromis variabilis". IUCN Red List of Threatened Species . 2006: e.T15458A4587788. doi: 10.2305/IUCN.UK.2006.RLTS.T15458A4587788.en . Retrieved 14 January 2018.
  4. 1 2 3 Graham M. (1929.) The Victoria Nyanza and Its Fisheries: A Report on the Fish Survey of Lake Victoria 1927–1928 and Appendices. London: Crown Agents for the Colonies. 256pp.
  5. 1 2 3 4 F. Witte, A. Goldschmidt, P. C. Goudswaard, W. Ligtvoet, M. J. P. van Oijen & J. H. Wanink (1992). "Species extinction and concomitant ecological changes in Lake Victoria". Netherlands Journal of Zoology . 42 (2–3): 214–232. doi:10.1163/156854291X00298.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  6. ↑ Meier, Marques, Mwaiko, Wagner, Excoffier, & Seehausen (2017). Ancient hybridization fuels rapid cichlid fish adaptive radiations. Nature Communications 8: 14363. DOI: 10.1038/ncomms14363
  7. ↑ Verheyen, Salzburger, Snoeks, and Meyer (2003). Origin of the Superflock of Cichlid Fishes from Lake Victoria, East Africa. Science 300: 325—329.
  8. 1 2 3 Tijs Goldschmidt; Frans Witte; Jan Wanink (1993). "Cascading effects of the introduced Nile perch on the detrivorous/phytoplantivorous species in sublittoral areas of Lake Victoria". Conservation Biology . 7 (3): 686–700. doi:10.1046/j.1523-1739.1993.07030686.x. JSTOR   2386700.
  9. 1 2 Tijs Goldschmidt (1998). Darwin's Dreampond: Drama in Lake Victoria. Trans. S. Marx-Macdonald. Cambridge, MA: MIT Press. ISBN   978-0-262-57121-0.
  10. ↑ Geoffrey Fryer; T. D. Iles (1972). The Cichlid Fishes of the Great Lakes of Africa . Edinburgh: Oliver & Boyd. ISBN   978-0-05-002347-1.
  11. 1 2 M. Graham (1929). A report on the fishing survey of Lake Victoria 1927–1928 and Appendices. London: Crown Agents for the Colonies.
  12. 1 2 George W. Coulter; Brian R. Allanson; Michael N. Bruton; P. Humphry Greenwood; Robert C. Hart; Peter B. N. Jackson; Anthony J. Ribbink (1986). "Unique qualities and special problems of the Great African Lakes". Environmental Biology of Fishes . 17 (3): 161–183. doi:10.1007/BF00698196. S2CID   3063490.
  13. ↑ R. J. H. Beverton (1959). A report on the state of the Lake Victoria fisheries. Lowestoft: Fisheries Laboratory.
  14. 1 2 3 4 A. M. Anderson (1961). "Further observations concerning the proposed introduction of Nile Perch into Lake Victoria". East African Agricultural and Forestry Journal. 26 (4): 195–201. doi:10.1080/00128325.1961.11661723.
  15. 1 2 3 4 A. P. Achieng (1990). "The impact of the introduction of the Nile Perch, Lates niloticus (L.), on the fisheries of Lake Victoria". Journal of Fish Biology . 37, Suppl. A: 17–23. doi:10.1111/j.1095-8649.1990.tb05016.x.
  16. ↑ R. H. Lowe-Mcconnell (1994). "The changing ecosystem of Lake Victoria, East Africa". Freshwater Forum . 4 (2): 76–89.
  17. ↑ S. Worthington; E. B. Worthington (1933). The inland waters of Africa: the result of two expeditions to the Great Lakes of Kenya and Uganda, with accounts of their biology, native tribes and development. London: MacMillan.
  18. 1 2 3 G. Fryer (1960). "Concerning the proposed introduction of Nile Perch into Lake Victoria". East African Agricultural Journal. 25 (4): 267–270. doi:10.1080/03670074.1960.11665278.
  19. 1 2 C. F. Hickling (1961). Tropical Inland Fisheries . London: Longmans.
  20. ↑ R. S. A. Beauchamp (1954). "Fishery research in the lakes of East Africa". East African Agricultural Journal. 19 (4): 203–207. doi:10.1080/03670074.1954.11664909.
  21. ↑ M. J. Mann (1969). "Appendix B. A resumé of the evolution of the Tilapia fisheries up to the year 1960". EAFFRO Annual Report 1969. Jinja: East African Freshwater Fisheries Research Organisation.
  22. 1 2 J. S. Balirwa (1992). "The evolution of the fishery of Oreochromis niloticus (Pisces: Cichlidae) in Lake Victoria" (PDF). Hydrobiologia . 232 (1): 85–89. doi:10.1007/BF00014616. S2CID   7495244.
  23. ↑ J. M. Gee (1964). "Appendix A. Nile perch investigations". EAFFRO Annual Report 1962/63. Jinja: East African Common Services Organization & East African Freshwater Fisheries Research Organisation. pp. 14–24.
  24. ↑ J. E. Reynolds; D. F. Greboval; P. Mannini (27–31 March 1992). Thirty years on: observations on the development of the Nile perch fishery in Lake Victoria. Symposium on Impact of Species Changes in African Lakes, Renewable Resources Assessment Group. Imperial College, London. p. 4.
  25. ↑ C. D. N. Barel; W. Ligtvoet; T. Goldschmidt; F. Witte; P. C. Goudswaard (1991). "The haplochromine cichlids in Lake Victoria: an assessment of biological and fisheries interests". In Miles H. A. Keenleyside (ed.). Cichlid Fishes: Behaviour, Ecology and Evolution. London: Chapman and Hall. pp. 258–279. ISBN   978-0-412-32200-6.
  26. ↑ DeWeerdt, S. (28 February 2004). Dark secret of the lake. New Scientist. Retrieved 26 March 2017.
  27. ↑ Lowe-McConnell, R. (2009). Fisheries and cichlid evolution in the African Great Lakes: progress and problems. Freshwater Reviews 2: 131-151.
  28. ↑ van Rijssel; and Witte (2013). Adaptive responses in resurgent Lake Victoria cichlids over the past 30 years. Evol.Ecol. 27:253–267. DOI: 10.1007/s10682-012-9596-9.
  29. ↑ Fiedler, P.L.; and P.M. Kareiva, editors (1998). Conservation Biology: For the Coming Decade. 2nd edition. Pp. 209—210. ISBN   978-0412096617
  30. ↑ Jan H. Wanink & Kees (P. C.) Goudswaard (1994). "Effects of Nile perch (Lates niloticus) introduction into Lake Victoria, East Africa, on the diet of Pied Kingfishers (Ceryle rudis)". Hydrobiologia . 279–280 (1): 367–376. doi:10.1007/BF00027868. S2CID   25284942.
  31. ↑ John S. Balirwa, Colin A. Chapman, Lauren J. Chapman, Ian G. Cowx, Kim Geheb, Les Kaufman, Rosemary H. Lowe-McConnell, Ole Seehausen, Jan H. Wanink, Robin L. Welcomme & Frans Witte (2003). "Biodiversity and fisheries sustainability in the Lake Victoria basin: an unexpected marriage?". BioScience . 53 (8): 703–716. doi: 10.1641/0006-3568(2003)053[0703:BAFSIT]2.0.CO;2 .{{cite journal}}: CS1 maint: multiple names: authors list (link)
  32. ↑ France Witte; Monique Welten; Martin Heemskerk; Irene van der Stap; Lisanne Ham Hendrikus Rutjes; Jan Wanink (2008). "Major morphological changes in a Lake Victoria cichlid fish within two decades". Biological Journal of the Linnean Society . 94 (1): 41–52. doi: 10.1111/j.1095-8312.2008.00971.x .
  33. 1 2 Kim Geheb; Sarah Kalloch; Modesta Medard; Anne-Therese Nyapendi; Carolyne Lwenya; Mercy Kyangwa (2008). "Nile perch and the hungry of Lake Victoria: Gender, status and food in an East African fishery". Food Policy . 33 (1): 85–98. doi:10.1016/j.foodpol.2007.06.001.
  34. 1 2 3 LVFO (Lake Victoria Fisheries Organisation) (2005). Regional report on Lake Victoria Frame surveys for 2000, 2002 and 2004. Jinja, Uganda: LVFO and the Lake Victoria Environmental Management Project.
  35. ↑ C. Asowe-Okwe (1996). "Abavubi: an examination of the living and working conditions of fish labourers of Lake Kyoga and Victoria (Uganda)". In Mahmood Mamdani (ed.). Uganda, Studies in Labour. Dakar, Senegal: Council for the Development of Social Science Research in Africa. pp. 181–240. ISBN   978-2-86978-059-0.
  36. ↑ Craig K. Harris; David S. Wiley; Douglas C. Wilson (1995). "Socio-economic impacts of introduced species in Lake Victoria fisheries". In Tony J. Pitcher; Paul J. B. Hart (eds.). The Impact of Species Changes in African Lakes. London: Chapman and Hall. pp. 215–242. ISBN   9780412550508.
  37. ↑ "State of fish stocks". LVFO (Lake Victoria Fisheries Organisation). 2007. Archived from the original on 2011-07-27.
  38. ↑ "Bulago Island initiative bears fruits". New Vision. Retrieved 2023-08-30.
  39. ↑ The Economist, March 28th 2020, "The African century", page 9.
  40. ↑ J. Joost Beuving (2010). "Playing pool along the shores of Lake Victoria: Fishermen, careers and capital accumulation in the Ugandan Nile perch business". Africa . 80 (2): 224–248. doi:10.3366/afr.2010.0203. S2CID   145457096.
  41. ↑ C. T. Kirema-Mukasa; J. E. Reynolds (1991). Marketing and consumption of fish in Uganda. FISHIN Notes and Records: Occasional Papers No. 4. Food and Agriculture Organization.
  42. ↑ Richard O. Abila; Eirik G. Jansen (1997). "From local to global markets: the fish exporting and fishmeal industries of Lake Victoria – structure, strategies and socio-economic impacts in Kenya" (PDF). Socio-economics of the Lake Victoria fisheries: Report No. 2. Nairobi: IUCN Eastern Africa Programme.
  43. ↑ Eirik G. Jansen (1997). "Rich fisheries-poor fisherfolk: some preliminary observations about the effects of trade and aid in the Lake Victoria fisheries" (PDF). Socio-economics of the Lake Victoria fisheries: Report No. 1. Nairobi: IUCN Eastern Africa Programme. Archived from the original (PDF) on 2012-03-31. Retrieved 2012-02-21.
  44. ↑ J. Mugabe; E. G. Jansen; B. Mak'Ochieng. "Foreign cash for local food insecurity? Socio-economic impacts of liberalized trade in Lake Victoria's fisheries. Lake Victoria Policy Brief". Nairobi, African Centre for Technology Studies.
  45. 1 2 K. Geheb; M. Modesta Medard; M. Mercy Kyangwa; C. Lwenya (2007). "The future of change: roles, dynamics and functions for fishing communities in the management of Lake Victoria's fisheries" (PDF). Aquatic Ecosystem Health & Management . 10 (4): 467–480. doi:10.1080/14634980701704098. S2CID   83777385. Archived from the original (PDF) on 2012-03-31. Retrieved 2012-02-21.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.