The present study demonstrates the declining state of the major commercial fisheries of Lake Victoria, Kenya, a situation threatening sustainability of the lake's fishery. Data in the present study were derived from resource monitoring programmes that included hydro‐acoustics (2009–2018), trawl net fishing (2011–2018), frame surveys (2000–2016) and catch assessment surveys (2000–2015). The activities provided information on fish stocks and supported advice for fisheries management. The average fish stock densities for Tanzania, Uganda and Kenya of 8.92, 8.25 and 8.19 t/km2, respectively, were relatively similar. Diplomatic and sustainable efforts for harmony in fish harvesting among the fishers of the riparian countries are encouraged given the interdependence of the lake. The Kenyan and River Kagera regions had a higher proportion (≈ 4% each) of big‐sized Nile perch (≥50 cm total length) in 2018, signifying the critical breeding areas for Nile perch. To sustain the fishery, there is need to enforce a 36%–44% effort reduction for all the major fisheries, and enforcement of gear limits to avoid harvesting of immature fish and destruction of the lake ecosystem.

Links between corruption and illegal practices within fisheries are recognised in existing literature but little reference has been made to how these interconnected practices affect the performance and legitimacy of fisheries comanagement. Research in the three countries bordering Lake Victoria, Kenya, Tanzania and Uganda, found that corruption is systemic and that members of all stakeholder groups-fishers, fisheries officers, police and the judiciary-are implicated. It was confirmed that corruption is strongly linked to illegalities and that corruption in this context should be viewed as a collective action problem, with fishers reluctant to invest in legal gears and methods when they perceive illegalities and corruption to be prevalent. It was also found that corrupt practices linked to illegalities discourages local level fisheries management structuresthe Beach Management Units-from enforcing regulations and contributes to a lack of trust between fishers and government. Linked corruption and illegal fisheries practices were therefore found to be undermining the performance and legitimacy of co-management. This article concludes that whilst co-management offers opportunities for collusive corruption through collaborative arrangements, any management system will be susceptible to the harmful effects of corruption where it is systemic and is not formally recognised or appropriately addressed. Greater official recognition of the links between corruption and illegalities, and a range of appropriate actions taken to this collective action problem, is essential if co-management is to have a chance of success.

This study investigated the growth, mortality and recruitment of Lates niloticus in Lake Victoria basis on length–frequency data collected during the period 2014‐2015. The asymptotic length (L∞) had a value of 124 cm TL, growth curvature (K) of 0.22 year−1, total mortality (Z) of 0.96 year−1, a natural mortality (M) of 0.42 year−1, a fishing mortality (F) of 0.54 year−1, an exploitation rate (E) of 0.57 and a growth performance index (normal∅) of 3.53. Logistic selection model showed that 50% of fish of 46.09 cm TL encountering the gear are retained. There were two peak recruitment periods, a minor one in March and a major one in July, accounting for 12.04% and 22.04%, respectively, of the total fish catch. The Beverton and Holt's relative yield‐per‐recruit model indicated the indices for sustainable yields are 0.32 for optimum sustainable yield (E0.5), 0.60 for maximum sustainable yield (Emax) and 0.51 for economic yield (E0.1). Compared to previous findings, there is a great decline in the sizes of Nile perch stocks in Lake Victoria. Thus, managing the fishery requires strict adherence to the slot size of 50–85 cm TL, and restrictions on illegal gear and methods, by the devolved governments through monitoring, control and surveillance in liaison with the Beach Management Units (BMUs).

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This study reports on the population parameters, catch distribution and feeding ecology of Nile tilapia (Oreochromis niloticus) from bottom trawls and commercial catches obtained in the Kenyan portion of Lake Victoria during 1997-2006. The population parameters were analysed using the FAO-ICLARM stock assessment tool (FISAT). The fish biomass and the food ingested by the fish were estimated using the swept area and point methods, respectively. Immature fish comprised ഠ70% of the total fish population. The asymptotic length, maximum weight, maximum age, exploitation rate (E) and length at 50% maturity of Nile tilapia have decreased, whereas the growth curvature and fishing mortality have increased. The commercial catches increased from 13.93 t in 1997, to 23.70 t in 1999, decreasing thereafter to 18.73 t in 2005. The bottom trawl catches increased from 46.90 kg ha -1 in 1997, to 401.48 kg ha -1 in 2000, decreasing thereafter to 15.57 kg ha -1 in 2006. The major food items ingested by the fish were algae, insects and other fish. Population parameters, and the catch and diet of O. niloticus, have changed over the years in Lake Victoria. The population characteristics suggest a population under stress, attributable to intense catch exploitation. Even under intense exploitation (E = 0.68), however, the mature fish constituted ഠ30% of the population. The commercial catches are still high, indicating a very resilient fishery. Nevertheless, despite this resilience, the future of Oreochromis fishery is threatened by increased fishing capacity in the lake, and there is need to re-evaluate the effectiveness of current fishery management measures, with the goal of possibly adopting new measures. Enactment of new fishery policies also should provide for co-management to enhance the management process. Furthermore, there is a need to reduce fishing capacity and illegal fishing methods, and to seek alternative livelihoods for lake fishers and other stakeholders.