Four decades after the initial export of Nile Perch from Lake Victoria, which reached an annual maximum harvest of 330,000 tons in 2000 (LVFO, 2009), Nile Perch resources are under pressure. With a form of co-management in place, it is not clear who is responsible for resources management. The fishers claim the Governments are responsible and the Governments say that the fish export industry is responsible. Results of six years of research led the Council of Ministers of the Lake Victoria Fisheries Organization in 2003 to endorse the recommendation to enforce drastic measures. When the measures came into force they were strictly adhered to, but with time, the authorities unwillingly relaxed them until draconian measures then had to be taken. Identical measures were adopted by the Council in 2009 and this resulted in the professional fish export associations rigidly maintaining one portion, while claiming that no scientific evidence existed for the other part.

The co-management system making use of Beach Management Units (BMU) is well developed on Lake Victoria, but has only been partly introduced to the shores of Lake Tanganyika, where certain management structures have existed for many years. This article discusses how the state of the optimum fish stocks could be regenerated, but notes that other external factors may also play roles (including climate change).

On Lake Tanganyika an industrial fishery was operational in the northern part of the lake from the mid-1970s to the mid-1990s, which gradually moved southwards with time and was outcompeted by the emerging artisanal fishery, whose effort is still increasing.

Whilst riparian Governments subscribe to international action plans, messages have to be put across to the fishing communities about regeneration of lake ecosystems.

Introduction

The degradation of inland aquatic habitats through decades of human activities has led to massive efforts to rehabilitate freshwater habitats for fisheries and aquatic resources in watersheds throughout the world (Roni et al., 2005). Roni et al. reviewed hundreds of studies and summarized what is known about the effects of various techniques for restoring natural processes, improving habitat, and increasing fish and biotic production. Goudswaard et al. (2002) suggested that recruitment of fish was affected negatively, particularly Lungfish, due to large-scale conversion of wetlands to agricultural land.

The fisheries on the two largest lakes of Africa, Lakes Victoria and Tanganyika, are under pressure. This article deals with fisheries restoration which, is a rather vague term. Therefore, agreement on the exact terminology is required: what can be restored on the two lakes? In the recent past there has been talk of restoring (or regenerating) the inshore habitats, ecotones and wetlands that border Lake Victoria in Uganda. Projects such as these may be very costly which could be the reason why restoration or regeneration of these wetlands has not occurred as yet.

The two Great Lakes in East Africa, Victoria and Tanganyika, on which approximately 45 million people depend directly or indirectly for their livelihoods, are using fisheries practices that are not sustainable. Fisheries resources are seriously threatened by overexploitation and post-harvest losses. Rigorous action will have to be taken to restore the situation. It is, however, recognized that competent authorities cannot implement this by themselves; they require co-managing assistance from the other stakeholders in the fisheries and in the lakes (Geheb and Crean, 2000). The Lake Victoria BMU experiment has been going on for over a decade and must be seriously evaluated before the formula is transferred to Lake Tanganyika, where the process of (organized) co-management is about to begin.

Lake Victoria

The modification of some of Lake Victoria's riparian wetlands in the recent past may be irreversible, as reclaimed areas have been populated or are being used for agricultural and timber production. It is unknown to what extent these modifications affected the fisheries yields of the lake, mainly due to lack of monitoring and evaluation procedures.

Lake Victoria's fisheries have an interesting history. Until the introduction of the Nile Perch and Nile Tilapia (Lates niloticus and Oreochromis niloticus), the only exploited fish varieties were the Haplochromis species flock and the autochthonous group of tilapia species (Ogutu-Ohwayo, 1990; Witte et al., 1992a,b, 1999; Goudswaard, 2006). The fish harvests were mainly for national consumption. In the late 1970s and early 1980s the Nile Perch became the dominant species in fish catches and formed the backbone of a regional export industry. Initially frozen fish was exported but with time the majority of fish products were exported in fresh form (Cowx et al., 2003; Johnson, 2010; Van der Knaap and Ligtvoet, 2010).

Lake Victoria's water level has been regulated since the late forties by the Owen Falls dam in Jinja, Uganda, where the River Nile is claimed to have its source. The hydropower plant draws water from the lake, and this has caused rather low lake levels in years poor in rainfall. As international conventions exist with countries downstream of Lake Victoria, it is not possible to regenerate the lake levels from the time before the dam was constructed.

That leaves the fishery itself to be rehabilitated to levels where production may become sustainable (again). Fishing effort has grown dramatically in the past decade, attracting more and more fishermen into the fisheries with different target species like Nile Perch, Nile Tilapia and Rastrineobola argentea. Van der Knaap and Ligtvoet (2010) considered the size of the fishery in 2002 to be of a sustainable level. Since then, however, the total number of fishermen, motorized canoes, numbers of legal as well as illegal fishing gears increased again dramatically (LVFO, 2009). As the fishery needs to be rehabilitated, a choice must be made regarding various points in time: should the fishery go back to the pre-Nile Perch era, or perhaps the pre-water hyacinth era, or should only the Nile Perch fishery be addressed?

Lake Victoria's fisheries resources have been managed by the relevant authorities for a long period. Under British colonial rule cooking pots in the villages were overturned and fish bones measured for compliance with minimum fish sizes used for food. Since independence the three riparian countries developed their own fisheries management measures, which have been summarized by Van der Knaap et al. (2002). One of the most remarkable successes of fisheries management on Lake Victoria was the removal of trawlers from the lake. It was concluded at the time that trawling had too big an impact on fish stocks, not only on Nile Perch, but also on demersal fish species that used trawlable bottoms for their breeding pits (Mkumbo, 2002).

The total fish output from Lake Victoria has been a topic of discussion, particularly since 2005. Until that year a more or less constant output was arrived at, but then the fisheries harvest started to increase considerably. Figure 1 shows the evolution of total catches on Lake Victoria. It is remarkable that when the new data collection system was introduced the total catches of Haplochromines increased from 1,020 tonnes in 2003 to 112,000 tonnes in 2005 and up to 146,000 tonnes in 2006, which is approximately 100 thousand tonnes more than in 1978 when the Haplochromines reached their maximum harvest before the Nile Perch boom. The same may be valid for Nile Perch. In 2006 a total of 264 thousand tonnes would have been harvested, which was of the same order of magnitude as during the peak years in 1994–1995 (although not as high as the Nile Perch output in 1988–1990, when it exceeded 300 thousand tonnes).

Nile Perch fishermen were complaining about the lack of fish; fish processors could not obtain sufficient raw material to satisfy their clients overseas. As a result, factories had to shut their doors, staff were laid off, and both fishermen and auxiliary fish workers suffered tremendously. As there was no legal destination for the fish caught, a parallel market developed where undersized fish found its way to regional customers. The extent of the trade is not known but it is believed to be substantial, particularly because of the fact that such large numbers of illegal fishing gears were encountered during the biannual frame surveys (LVFO, 2009). The question arises as to why the Nile Perch fisheries sector complained about the lack of raw materials and at the same time the official catch statistics went up.

The results of the hydro-acoustic surveys carried out on the lake indicate a declining trend for Nile Perch and an increasing one for Dagaa, whereas the total relative biomass fluctuates around two million tonnes of fish.The species composition has changed dramatically and, therefore, so has the potential total value of the resource (Figure 2).

Van der Knaap and Ligtvoet (2010) calculated the total value of the Nile Perch since the peak of its production in 1989 up to 2000. A total quantity of 3.5 million tons of Nile Perch had been harvested, which represents in monetary terms an amount of 2.5 billion US dollars, at an average price of $0.70 US per kg. This amount was the value on the beaches, i.e. the amount paid to the fishermen. Such an amount should have enabled fishermen to escape from the poverty trap, but unfortunately no saving possibilities were available. Had savings been made, the fishermen could have afforded to be subjected to certain management measures, like for instance close seasons, or to purchase nets with larger mesh sizes.

There are therefore no financial means to survive when catches are low. (Van der Knaap and Ligtvoet, 2010). With the current pressure on the resources, the catch rates of the fishermen decreased, but still prices on the beach are relatively high (of the order of US$ 2 per kg). The fishermen continue to exert fishing effort in order to survive and more and more illegal fishing gears enter the fishery, including destructive monofilament nets.

There is a definite financial incentive to restore the fishery. Cowx et al. (2003) reported on the various import and export bans of Nile Perch. The most serious fishing ban was due to the use of noxious chemicals to catch fish, which lasted little less than a year. Upon lifting the ban, fishermen returned to the lake and landed bumper catches for some time. This is an indication that a reduction in effort can lead to rapid recovery of the stocks of Nile Perch. It should be noted, however, that the export ban was only for the European Union. Some firms continued fishing and exporting to destinations outside the EU. Thus fishing effort was not reduced to zero at the time of the ban.

Lake Tanganyika

On Lake Tanganyika, an industrial fishery was operational in the northern part of the lake from the mid-1970s to the mid-1990s, which gradually moved southwards with time and was outcompeted by the emerging artisanal fishery, whose fishing effort is still on the increase. In 1999, a Framework Fisheries Management Plan for Lake Tanganyika (FAO, 1999) was prepared but then was shelved for over ten years. This implies that the management of the fisheries resources of the lake was not a priority. It should be taken into account that two of the lake's riparian countries went through periods of civil strife and related unrest. Furthermore all the four countries had to deal with Internally and Internationally Displaced People. Fisheries statistics are incomplete or non-existent. Biomass estimates date back to the previous millennium, and in the meantime a possible change in fish migration took place, which could be linked to climate change.

Many changes occurred in the fisheries during the past two decades, but little attention has been paid to managing or controlling them. Harmonization of fisheries legislation has been considered but is not yet on the diplomatic agenda. Also, adaptation of the fiscal systems in the riparian countries will be required. Socio-economic surveys yielded information that newcomers (returning refugees) into the fisheries cannot be refused when they wish to go fishing and therefore the fishing effort continues to increase. The four Governments are conscious of the problems but find it difficult to take proper action. Despite the regional initiative to start up a fisheries assistance project, as part of a wider development intervention, with confirmed funding, the countries find it difficult to undertake the assignment of managing the resources. Since insufficient manpower is available, the countries should resort to involving the local communities. The question remains whether the same system should be adopted as in place on Lake Victoria.

It is high time to review the existing means for fisheries management and to discuss a formula for community involvement in managing the fisheries resources of Lake Tanganyika. Theoretically the communities may play an important role in Monitoring, Control and Surveillance, but in practice that may require considerable effort to sensitize these communities. An automated MCS system, making use of newly developed technology (e.g. Vessel Monitoring System), could be considered, which would not only monitor the national fleets, but also strongly contribute to safety on the lake as movements of individual fishing units (as well as transport and leisure boats) can be monitored on land. But cheaper ways exist than monitoring via satellite-based communication.

The entire regional fisheries management and governance system has to start basically at the drawing board, and as a result it may take a number of years before an effective system can be put in place. As all relevant authorities are convinced that action needs to be taken promptly, the logical approach would be through the fishing communities and other related stakeholders. This forms part of the ecosystem-based approach to fisheries management, applying the Code of Conduct for Responsible Fisheries (FAO, 1999, 2003).

What hope is there of rehabilitation if natural climatic conditions change and cause increased stratification in the water column, which in its turn leads to loss of nutrient supply in near-surface waters? There will be less plankton and as a result less food for the small pelagic fish species in the euphotic zone of the lake (Verburg and Hecky, 2007). Wind patterns may change also causing less mixing of the water layers (Langenberg et al., 2003).

Fish abundance has been observed to move from North to South. Burundian waters in the northern part of the lake were teeming with fish, but an industrial fleet exploited the small pelagic species until the catch rates diminished to such low levels that the vessels could not economically operate any longer. The entire fleet moved from the northern part to Zambian waters in the South. The artisanal fleet remained in northern waters, where the fishing effort increased also in the last decade and catch rates declined (Figure 3).

From historical datasets the following information (Table 1) on maximum annual catches may be obtained:

Since there is currently a more politically stable situation in the eastern part of DR Congo, many Internally Displaced Persons are returning to their villages of origin. It is quite likely that their houses were destroyed during the period of civil unrest or became occupied by other people looking for shelter after their own dwellings were occupied or destroyed. Since 2007 many refugees who resided in Tanzania, Burundi and Zambia returned to the DR Congo's part of the Lake Tanganyika Basin. At the peak of remigration, approximately 1000 persons per week returned from Tanzania across the lake back to DR Congo. It has been observed that returnees arrived, fully dependent on hand-outs. It will take a long time before they can harvest vegetables or fruits from their own gardens. In order to feed the family, fishing on Lake Tanganyika was a means of last resort. Non-Governmental and UN Organizations, although meaning well, supplied returnees with fishing nets (not necessarily of the correct mesh size) to look after themselves. Instantly fishing effort in near-shore waters increased dramatically, exploiting juvenile small pelagic herring-like fish (Stolothrissa and Limnothrissa species). This is a typical problem with open-access fisheries.

Even if a licensing scheme is introduced in the near future, who will enforce this? Who will set the ceiling to the number of licenses to be issued? Another question is, why one person should have the right to fish and another one be denied a certificate? The introduction of such a system requires large-scale extension programmes and demonstrations of resource management (for instance demonstrating gillnet selectivity).

Data collection

The fisheries statistical data collections on Lake Victoria have been reviewed in 2003 (Cowx et al., 2003), and it was observed that the Fisheries Department in Kenya produced statistics considerably different from those collected by the institution responsible for fisheries research. Initially, the three countries were reluctant to harmonize their data collection systems as their national systems were based on catch statistics for natural lakes, rivers, reservoirs and the Indian Ocean (the latter being the case in Kenya and Tanzania). With the Lake Victoria Fisheries Organization in place, it was decided in 2006 to collect fisheries harvest data in a systematic way, following Standard Operating Procedures. It should be noted however, that the monthly data collection routines were replaced by simultaneous quarterly sampling exercises. The behavior of the small cyprinid fish species, Rastrineobola argentea (locally known as Omena, Mukene or Dagaa), is such that it can be attracted to a light source during dark nights (caused by the lunar phase and/or by cloud coverage). Therefore the choice of timing of the two weeks sampling is crucial for the estimation of harvest of these small cyprinids.

Although the data collection system on Lake Victoria is not ideal, at least two-yearly lake-wide frame surveys are conducted as well as quarterly Catch Assessment Surveys (CAS). On Lake Tanganyika the four riparian states conducted the first simultaneous frame survey in 1995 (Paffen et al., 1995) and the second in 2011 (LTA Secretariat, 2011a). In the period between the frame surveys the total numbers of fishermen and canoes doubled to approximately 100,000 fishermen and 29,000 fishing units. The four national CAS are different or non-existent.

Biodiversity

While Nile Perch catches were increasing in the 1980s, nobody knew how to conserve the fish and make use of this species. It was seen as a noxious animal eating away the unique biodiversity of the lake. By the time almost all the Haplochromine species susceptible to trawl nets were described, the Nile Perch had become so dominant that trawl catches were becoming mono-specific. A trawl fishery developed rapidly in the three riparian countries, exploiting the Nile Perch. A group of scientists concerned about the potential loss of biodiversity encouraged the fishermen to fish out the perch (Barel et al., 1985). This appeared more complicated than envisaged and three decades later the Nile Perch still occurs in Lake Victoria, despite the high fishing pressure.

The shallow rocky areas in various parts of the lake revealed a surprise for concerned scientists. Areas where trawlers had no access appeared swarming with rock-dwelling species. Research by Seehausen (1996) revealed a total of 175 different new species.

Estimates suggest that Lake Tanganyika harbours at least 1,500 species, although species numbers vary according to taxonomic authority. Approximately 600 species are endemic to the lake, including 245 morphologically diverse and colourful cichlid fish species. Lake Tanganyika is unique in harbouring endemic species clusters of bagrids, cyprinids, mastacembelids and mochokids. Fish species of commercial interest are Stolothrissa tanganicae, Limnothrissa miodon and Lates stappersii (LTA Secretariat, 2011b). An aquarium fish export sector exists, but due to limited numbers of international flight connections this has not (yet) further developed. Also, the status of the many ornamental fish species remains unknown.

Restoration and sustainable exploitation

Many commercial sustainable fisheries attempt to obtain the Marine Stewardship Council's certificate; this would have a positive effect on the retail prices in Europe and North America. Not all fisheries can obtain such a certificate as there must be evidence that the stocks are actively managed to deserve such a label. It is obvious that the Nile Perch fishery on Lake Victoria is not a sustainable one. There is, however, another organization, Naturland, which strives after sustainable exploitation, and has three criteria: ecological, social and economic sustainability. Though it may sound contradictory in an overexploited lake, there is an area near Bukoba, Tanzania, where the fishery would be sustainable and where the fishing communities contribute to the local management and benefit from the local advantages. If this indeed is a positive model, then its expansion should be considered.

Which other active measures could be taken in the three countries? Despite the repeated discussions on the issue, so far the Lake Victoria fisheries remain open-access fisheries. Licensing fishermen or fishing units would be the first step to control the fishing effort exerted on the different stocks. The question is who should be licensed? The size of the fishery in 2002 was considered to be of a sustainable level. Would it be socially acceptable to license the number of fishermen who were active in 2002? What would happen to the fishermen who entered the fishery after 2002 and invested in canoes, outboard engines and fishing gears? A licensing system is not introduced without difficulty. It is important that a ceiling be put on the number of licenses to be issued. If this equaled the total number of fishermen, according to the 2008 or 2010 frame survey, then this number should be licensed, but the fisheries managers may set the goal that after a certain number of years the total number be diminished by a certain percentage, and so on, until the level of, for example, 2002 has been arrived at. This may be in combination with ceilings to the number of canoes or the number of netting panels, etc.

The fish processing factories have shown their goodwill by sticking to the lower limit of the slot size that was imposed by the LVFO Council of Ministers for Nile Perch, being 50 cm total length. The upper limit is ignored as neither fishermen nor processors discard or refuse fish of more than 85 cm in total length.

The four Governments around Lake Tanganyika have endorsed the Lake Tanganyika Convention in 2007, and subsequently established the Lake Tanganyika Authority (LTA). In 2008, a US$70 million programme commenced to assist the four riparian nations in managing sedimentation and pollution problems, construction of relevant infrastructure, assistance to returning refugees and IDPs, and last but not least fisheries. The LTA on behalf of the Conference of Ministers responsible for environment and fisheries, is responsible for the regional aspects of fisheries and environmental management (http://www.lta-alt.org) assisted by four national coordination units, responsible for the national components. The LTA is in the process of deciding on the form of co-management to be introduced to Lake Tanganyika. Interesting experiences have been obtained in other fisheries, which were overexploited and where conflicts occurred among fishing communities. For example, in Korea a fishermen-oriented and community-based management system was introduced where so-called ‘servicemen’ represent the communities and are actively involved in self-management (Lee, 2010). Options for the co-management approach on Lake Tanganyika are still open and the existing traditional systems may be strengthened so that they can co-exist next to the BMU-system in the Tanzanian part of the lake.

Corrective measures and adaptive management

The Beach Management Units around Lake Victoria have a role to play, but to what extent have they been prepared for their responsible and important (voluntary) tasks? During a well-funded project (Implementation of a Fisheries Management Plan) it was envisaged to form 200 BMUs during the lifetime of the project; instead over one thousand were established and given powers that could hardly be handled by the fishermen. Involving the local fishermen and leaders at landing sites requires time and often NGO-involvement in order to train and sensitize people who are supposed to function as fisheries officers for a fixed period of time. During a four years’ project over 1000 BMUs were formed, which implies about one per day for the entire period (Njiru et al., 2010). Can the BMUs be expected to take their tasks seriously? Some of them appeared to have been very accommodating by burning nets of illegal mesh sizes. BMUs could play a role also by regulating fishing effort, first of all by recording it, and then later on by ‘distributing’ fishing days among the members. They will have to be involved when licenses, illegal mesh sizes, effort allocation and undersized fish are discussed.

It is unimportant which system will be adhered to on Lake Tanganyika, but similar functions and responsibilities as on Lake Victoria may have to be incorporated, particularly the option to form clusters of co-management units.

In 2010, the elders in certain fishing villages on the shores of Lake Tanganyika determined that several areas had to be closed for fishing as the local fishing effort exceeded all expectations. The problem was not immediately solved and the fishermen respected the closed areas, but continued fishing outside these areas. This led to transboundary conflicts. With continued increase in the number of fishermen and canoes, the number of conflicts will continue to grow. On Lake Tanganyika the presence of government officials is insufficient, therefore the fishing communities should become involved in the management of the fisheries resources. With Tanzania sharing Lakes Tanganyika and Victoria there is the likelihood that the formula of the BMU from Lake Victoria will be transferred to Lake Tanganyika. Here the fisheries managers need to be cautious as managing by local communities is more complicated than on Lake Victoria, where there are three border areas. On the much narrower Lake Tanganyika, it is easy to drift from Congolese into Tanzanian waters or vice versa. Thus the number of transboundary conflicts is potentially higher than on Lake Victoria. The persons to be elected to form the executive board or committee of the co-management unit need to be properly prepared and trained for the tasks ahead. Lessons learned from Lake Victoria should be applied to the situation on Lake Tanganyika.

Conclusions

The fisheries on Lake Victoria and Lake Tanganyika have a number of characteristics in common. First of all, in the last decade the fishing capacity increased immensely, putting a high pressure on the resources. Both lakes still have open-access fisheries, which are difficult to manage as the number of professionals and fishing units cannot be easily controlled. A considerable difference is the destination of the harvested fish. Lake Victoria fisheries exploit a species with a high export value, whereas the fisheries products on Lake Tanganyika largely contribute to food security in the area. As a result the access to money is larger on Lake Victoria than on Lake Tanganyika. In case the supply chain of Nile Perch is disrupted, by for instance cheap fish from South-East Asia (Van der Knaap and Ligtvoet, 2010), then the socio-economic impact will be harder around Lake Victoria than around Lake Tanganyika. Both lakes produce small pelagic fish, which increasingly become more expensive on Lake Victoria and which continue to be vulnerable to post-harvest losses on the shores of Lake Tanganyika. The way forward for both lakes will be the control of fishing capacity through licensing systems (and subsequent surveillance activities) as well as combating illegal fishing and fishing methods, with a considerable input from the local fishing communities. These communities will need to be further strengthened in the co-management practices and in operating co-management units. With the BMU system in place, Lake Victoria may seem to be in an advance position in terms of management success. It should be noted, however, that the approach on Lake Tanganyika is still flexible and with the lessons learned the process may yield more positive results than on Lake Victoria, where the BMU was initially geared towards beach and fish quality management rather than to fisheries resources management.

The text of this article is only available as a PDF.

References

Barel, C. D.N., Dorit, R., Greenwood, P. H., Fryer, G., Hughes, N., Jackson, P. B.N., Kawanabe, H., Lowe-McConnell, R. H., Nagoshi, M., Ribbink, A. J., Trewavas, E., Witte, F. and Yamaoka, K.
1985
.
Destruction of fisheries in Africa's lakes
.
Nature
,
315
:
19
20
.
Cowx, I. G., Van der Knaap, M., Muhoozi, L. I. and Othina, A.
2003
.
Improving fishery catch statistics for Lake Victoria
.
Aquat. Ecosyst. Health Mgmt.
,
6
(
3
):
299
310
.
FAO
.
1999
. “
Lake Tanganyika Framework Fisheries Management Plan. FISHCODE Management. FAO/Norway Programme of Assistance to Developing Countries for the Implementation of the Code of Conduct for Responsible Fisheries
”.
FAO/Norway Cooperative Programme (GCP/INT/648/NOR)
FAO
.
2003
. “
The ecosystem approach to fisheries. FAO Technical Guidelines for Responsible Fisheries
”.
Fisheries Department No. 4, Suppl. 2. Rome, FAO, Rome
Geheb, K. and Crean, K.
2000
. “
The Co-management Survey: Co-managerial perspectives for Lake Victoria's fisheries
”.
LVFRP Technical Document No. 11. LVFRP/TECH/00/11
Goudswaard, P. C.
2006
. “
Causes and Effects of the Lake Victoria Ecological Revolution
”.
The Netherlands
:
PhD Thesis, Institute of Biology, University of Leiden
.
Goudswaard, P. C., Witte, F. and Chapman, L. J.
2002
.
Decline of the African Lungfish (wq) in Lake Victoria (East Africa)
.
African Journal of Ecology
,
40
:
42
52
.
Johnson, J. L.
2010
.
From Mfangano to Madrid: The global commodity chain for Kenyan Nile Perch
.
Aquat. Ecosyst. Health Manage.
,
13
(
1
):
20
27
.
Langenberg, V. T., Sarvala, J. and Roijackers, R.
2003
.
Effect of wind induced water movements on nutrients, chlorophyll-a, and primary production in Lake Tanganyika
.
Aquat. Ecosyst. Health Mgmt.
,
6
(
3
):
279
288
.
Lee, S.-G.
2010
. “
Rebuilding fishery stocks in Korea: A national comprehensive approach
”. In
OECD, 2010. The Economics of Rebuilding Fisheries: Workshop Proceedings
,
Korea
:
College of Fisheries Sciences, Pukyong National University
.
LTA Secretariat
.
2011a
.
Report on Regional Lakewide Fisheries Frame Survey on Lake Tanganyika 2011. LTA/TECH DOC/2012/01
Bujumbura, , Burundi
LTA Secretariat
.
2011b
.
Strategic Action Programme for the Protection of Biodiversity and Sustainable Management of Natural Resources in Lake Tanganyika and its Basin
Bujumbura, , Burundi
LVFO
.
2009
. “
State of Fish Stocks
”.
Lake Victoria Fisheries Organization
.
Available from: http://lvfo.org/index
Mkumbo, O. C.
2002
. “
Assessment and management of Nile Perch (Lates niloticus L.) stocks in the Tanzanian waters of Lake Victoria
”.
UK
:
PhD Thesis, Hull University
.
Njiru, M., Mkumbo, O. C. and Van der Knaap, M.
2010
.
Some possible factors leading to decline in fish species in Lake Victoria
.
Aquat. Ecosyst. Health Mgmt.
,
13
(
1
):
3
10
.
Ogutu-Ohwayo, R.
1990
.
The decline of the native fishes of lakes Victoria and Kyoga (East Africa) and the impact of introduced species, especially the Nile Perch, Lates niloticus and the Nile Tilapia, Oreochroms niloticus
.
Environ. Biol. Fish
,
27
:
81
96
.
Paffen, P., Coenen, E., Bambara, S., Wa Bazolana, M., Lyimo, E. and Lukeswa, C.
1995
. “
Synthesis of the 1995 Simultaneous Frame Survey of Lake Tanganyika Fisheries. FAO/FINNIDA Research for the Management of the Fisheries on Lake Tanganyika
”.
GCP/RAF/271/FIN-TD/60 (En)
Roni, P., Hanson, K., Beechie, T., Pess, G., Pollock, M. and Bartley, D. M.
2005
. “
Habitat rehabilitation for inland fisheries. Global review of effectiveness and guidance for rehabilitation of freshwater ecosystems
”.
FAO Fisheries Technical Paper. No. 484. Rome, FAO
Seehausen, O.
1996
.
Lake Victoria Rock Cichlids: Taxonomy, Ecology, and Distribution
Verduijn Cichlids, Zevenhuizen (ISBN 90-800181-6-3)
Van der Knaap, M., Ntiba, M. J. and Cowx, I. G.
2002
.
Key Elements of Fisheries Management on Lake Victoria
.
Aquat. Ecosyst. Health & Mgmt.
,
5
(
3
):
245
254
.
Van der Knaap, M. and Ligtvoet, W.
2010
.
Is Western consumption of Nile Perch from Lake Victoria sustainable?
.
Aquat. Ecosyst. Health Mgmt.
,
13
(
4
):
429
436
.
Witte, F., Goldschmidt, T., Wanink, J., Van Oijen, M., Goudswaard, K., Witte-Maas, E. and Bouton, N.
1992a
.
The destruction of an endemic species flock: quantitative data on the decline of the haplochromine cichlids of Lake Victoria
.
Env. Biol. Fish.
,
34
:
1
28
.
Witte, F., Goldschmidt, T., Goudswaard, P. C., Ligtvoet, W., Van Oijen, M. J. P. and Wanink, J. H.
1992b
.
Species extinction and concomitant ecological changes in Lake Victoria
.
Nether. J. Zool.
,
42
:
214
232
.
Witte, F., Goudswaard, T., Katunzi, E. F. B., Mkumbo, O. C., Seehausen, O. and Wanink, J. H.
1999
. “
Lake Victoria's Ecological changes and their relationships with the riparian societies
”. In
Ancient lakes: Their cultural and biological diversity
, Edited by: Kawanabe, H. H., Coulter, G. W. and Roosevelt, A. C.
189
202
.
Belgium
:
Kenobi Productions
.