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MultiTip ER - Enhancing Resilience

MultiTip ER focuses on enhancing the resilience of Lake Victoria fisheries and therefore, avoiding adverse tipping points. This work reflects an evolution in focus, co-designed with our local partners, that concentrates on the methods (the ‘how’) of exploitation, and therefore focus on the fishers’ choice of gear. 

Phase 2 research is separated into three work-packages (WP), each addressing a key dimension of resilience. In WP1, our bio-economic models examine the resilience of Lake Victoria as a multi-species system, reflecting new modelling insights on the role of size specificity in the fishery. This includes research on food web stability, particularly the role of Silver cyprinid in ecosystem dynamics (Task 1.1), and the effects of size-based fishing policies on yield and resilience (Task 1.2). 

In WP2, our field interventions investigate how input choices and market prices influence fishing behaviour. Specifically, we conduct field trials of subsidising sustainable dagaa fishing nets (Task 2.1) and and an analysis of non-compliance in renewable resource systems, focusing on a bait policy for the longline Nile Perch fishery (Task 2.2). 

Our governance work, in WP3, explores the cognitive and social dimensions of governance through surveys and experiments. This is divided into three sub-packages: WP 3.1 examines tipping points and user responses. WP 3.2 focuses on mental models, including fishers’ perceptions of stock decline (Task 3.2.1), stakeholder views on conservation and governance (Task 3.2.2), and adaptation strategies (Task 3.2.3). WP 3.3 explores governance acceptance and cooperation, analyzing fishers’ preferences for monitoring systems (Task 3.3.1) and cross-country differences in cooperation and punishment (Task 3.3.2).

Together, these studies provide a comprehensive understanding of resilience in Lake Victoria’s fisheries, integrating ecological, economic, and governance perspectives to support sustainable management.  

 

WP 1	Below the surface – Resilience of the resource system in a size-based multi-species model
WP 2	Interactions – Leveraging Input Choice as Focal Action Situation
WP 3	Above the surface – Surveys and experiments for mental models and acceptance of resilience-enhancing governance

 

 

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Below the surface – Resilience of the resource system in a size-based multi-species model

WP1 studies the stability of the fisheries and explores regime shifts and tipping points with a size-based multi-species model of the LV resource system. This is a natural extension from Phase 1 with its size-based single-species model of the Nile perch fishery. Building on the experiences from the first phase of MultiTip, we take this step towards a food web model including Nile perch, dagaa, and haplochromines. The comeback of haplochromines, together with sustained fishing pressure, could mean that the tipping of the resource system in the 1980s could be reversed soon, implying a collapse of the Nile perch stock. However, the food web today is different from the 1980s, especially due to the dagaa population. This might result in different interaction patterns between Nile perch and haplochromines with ecological niches that mitigate the instability.

Task 1.1 - Food web stability. The influence of Silver cyprinid on the stability in a size-based and an age-based multi-species model.

It is estimated that 200 haplochromine species have gone extinct in the last 50 years (Sayer et al., 2018). However, since 2005, the lake has seen a comeback of several haplochromine species (Kolding et al., 2014), which has profound consequences for the assessment of the stability of the lake (van Zwieten et al., 2016). Today, different from the 1970s, the silver cyprinid (Rastrineobola argentea, locally known as dagaa) has a large stock and is fished for protein supply of the local population (Nyamweya et al., 2022). It is an open question whether dagaa, as a prey for Nile perch, might increase the stability of the Nile perch population. 

To evaluate today’s ecosystem stability, we employ two modelling approaches. First, we use the mizer framework for building a size-based multi-species food web model (Delius et al., 2024). We calibrate the model for Nile perch, a (generalized) haplochromine species, and dagaa using biological measurements along catch and biomass data. This model captures the predator-prey relationships which are determined by the fish size, and thus allows to analyze the food chain. 

The second approach is the Atlantis ecosystem model. Atlantis is a spatially explicit, end-to-end ecosystem model that integrates physical, biological, and human system components (Fulton et al., 2011). The model represents key functional groups, including fish, invertebrates, plankton, and primary producers, along with environmental processes such as nutrient cycling and hydrodynamics. For this study, we configure Atlantis using parameterizations tailored to Lake Victoria, incorporating site-specific data on species interactions, habitat structure, and fishing effort. The model is initialized with historical ecosystem conditions. 

We compare two scenarios: One represents the present state of the lake, one represents a counter-factual state without dagaa. In the second scenario, after the system has reached equilibrium, the dagaa population density is set to zero, and the model is run for another 30 years. In the mizer model, we find that there is a co-existence state, with biomasses roughly similar to the observations. Without the existence of the dagaa population, the Nile perch stock would decrease by about 18% in biomass, while the haplochromine stock would be 29% bigger (Figure 1). This shows that the Nile perch stock benefits from the existence of dagaa (due to prey availability), while dagaa is a disadvantage to haplochromines (due to competition for resources). 

Atlantis is run for the same scenarios as mizer. In contrast to the pronounced changes in Nile perch biomass predicted by the mizer model, the Atlantis simulations show a more moderate response of Nile perch to the removal of dagaa (Figure 2). Under both scenarios—one with dagaa present and one without dagaa—Nile perch biomass remains relatively stable over the 45-year simulation. Although there is a dip in biomass in the absence of dagaa, this  decrease is considerably smaller than the ~18% reduction predicted by the mizer model. Instead, Nile perch appears to compensate for the missing dagaa through alternative trophic pathways, indicating a more diverse prey base or additional food web interactions accounted for in the Atlantis framework.

These findings are further reflected in the catch projections (Figure 3). While the overall catch of Nile perch shows minor fluctuations between the two scenarios, the difference is not as pronounced as expected from the simpler size-based model. Even in the absence of dagaa, the fishery for Nile perch remains robust, suggesting that other prey species—such as various haplochromines—partially offset the loss of dagaa in the Atlantis model. The divergence of the Atlantis predictions from the mizer results highlights how the complex food chains of the ecosystem, captured in more details in the Atlantis model, can buffer against the removal of a single forage species.

 

 

Researchers: Dr. Johannes Kammerer, Dr. Chrisphine Nyamweya (KMFRI), Prof. Dr. Anna Marciniak-Czochra

 

Task 1.2 - Size-based fishing policies. Effects of fishing patterns on yield and resilience in the multi-species ecosystem of Lake Victoria.

A fishery that targets a predator more strongly reduces the predation pressure on its prey. Hence the effect of fishing propagates down the food chain, and the total effect depends heavily on the typical mass ratio of predator and prey (Law et al., 2009). In populations with intraspecific competition and cannibalism (like Nile perch), the predation effect leads to oscillating dynamics (Law et al., 2015). 

We use the model developed in Task 1.1 to extend the research from the first phase of MultiTip and study the effect of four fishing patterns related to the slot size regulations in the mizer model. This allows us to detect whether or not there exist adverse effects of a modified fishing pattern, such that we can review the results from the first phase and assess their robustness. 

We integrate the four scenarios from the first phase (Kammerer, J., Gómez-Cardona, S., and Nyamweya, C., 2022) in the mizer model and modify the fishing pattern of the gillnet fleet accordingly: First, with fishing selectivity in a “business as usual” (BAU) scenario; second, no fishing below 50cm; third, no fishing above 85cm; forth, fishing only between 50-85cm. In each scenario, we start from the BAU equilibrium, introduce the respective fishery selectivity and then simulate 30 years into the future. We assess the final state’s biomass composition and catch rates. 

We find that sparing Nile perch below 50 cm leads to substantial increases in stock biomass and yield, compared to business as usual. The biomass increases from about 600 kt to almost 3000 kt, the yield from about 170 to 800 kt/yr, which is an almost five-fold increase (Figure 4). The temporal development of the transition is as follows: Directly after the fishery stops catching Nile perch below 50 cm, the yield from gillnets increases because the growth potential of the fish is more fully realized (Kammerer, 2024). The period of increasing gillnet catches takes about three years. Afterwards, a bigger stock of large adult Nile perch has built up, which increases the death rates of younger fish through cannibalism, leading to a slight decrease in gillnet yield. This coincides with the longline catches reaching the steady state plateau, which is around seven years into the simulation. Scenario three (sparing only fish above 85 cm) is similar to the BAU scenario, and scenario four (adhering to the slot size) is similar to the scenario where only fish below 50 cm are spared. This means that the qualitative result found in the single species model of phase one holds also in the three species food web model.

Researchers: Dr. Johannes Kammerer, Dr. Chrisphine Nyamweya (KMFRI), Prof. Dr. Anna Marciniak-Czochra.

 

Back to Phase 2 Introduction

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Interactions – Leveraging Input Choice and Price as Focal Action Situation

Phase 1 has provided evidence of the potential to improve or find alternatives to existing input regulations in the LV fisheries. WP2 will apply these lessons to two focal action situations: the use of unsustainable nets in the dagaa fishery (Task 2.1) and the use of wild-caught bait in the Nile perch fishery (Task 2.2). Jointly, the tasks generate outputs that can be readily used to inform current and intended changes in gear regulations. 

In renewable resource systems (Hilborn et al., PNAS 2020) and other environmental contexts (Gray and Shimshack, REEP 2011), monitoring and punishment are common tools for increasing the cost of non-compliance. Enforcement, especially in fisheries management, often targets inputs; for example, in Lake Victoria, regulations mandate mesh sizes of fishing nets and hook sizes of longline gear to reduce juvenile fish catch and support stock replenishment (LVFO, 2016). However, these tools often fail. Typical reasons are that the cost of effective monitoring is excessive (Kastoryano & Vollaard, JEEM 2023) or that punishment is non-credible (Duflo et al., E’metrica 2018).

We use two studies to test methods of increasing compliance in Lake Victoria fisheries. In the first study, we test the conjecture that subsidizing fishing net panels can increase compliance to LVFO mesh-size recommendations in the dagaa (Silver cyprinid) fishery. In the second study, we explore whether aqaculture bait - a sustainable, compliant input - can replace the widely used wild-caught bait – a non-compliant input - in Nile perch longline fishery. 

Task 2.1 - Subsidizing Compliance: A field experiment on discounted sustainable dagaa fishing nets at Lake Victoria.

We test the conjecture that subsidizing compliance can be a substitute for monitoring and punishment in a renewable resource system with enforcement challenges. The silver cyprinid or dagaa fishery is the largest at Lake Victoria in terms of biomass extracted (500,000 metric tons, LVFO 2016) and the second-largest in terms of market value (US$135m, LVFO 2016). Its sustainability is deemed under threat: Regulators suspect that the prevalent use of fishing nets with small mesh-sizes causes excess extraction of juvenile fish, reducing the reproductive capacity of the fishery. However, enforcement of mesh-size regulations is either absent (Kenya) or costly and ineffective (Tanzania).

We employ a RCT with nearly 800 boatowners at Lake Victoria, Tanzania and Kenya, where we offer compliant net panels for sale. Net panels present a suitable opportunity as they are an affordable (US$20 per panel) production input with short-term durability (replacement every 3 to 6 months due to wear and tear). The typical boat-owner must replace around three to six panels every month, creating continuous demand. The size-stratified cluster randomization at the landing site level leads to two types of landing sites, those where boatowners are offered compliant net panels at normal (control sites) or at discounted prices (treatment sites). We study differences in two key outcome variables: (1) the level of non-compliance, as measured by the number of non-compliant panels found with boat-owners; and (2) the demand for compliant panels purchased during visits. 

We have two main results. First, comparing the presence of non-compliant panels between the initial and follow-up visits at treated and control sites, we find that in the absence of enforcement (Kenya)– for each boat-owner – a discount of US$10 on compliant panels crowds out an average of 1.5 non-compliant panels. Second, comparing the difference in the likelihood of purchasing a panel during the follow-up visit between treated and control sites, we find that treatment significantly increases the likelihood of purchase. In Tanzania, where mesh size enforcement exists, we do not see any significant changes in the use of non-compliant net panels, but, three months later, the demand for discounted panels is sustained. 

Researchers: Sorell de Silva (Ph.D. Candidate), Dr. Tillmann Eymess, Prof. Timo Goeschl Ph.D, Prof. Dr. Florian Diekert, Joseph Luomba, M.Sc. (TAFIRI), Horace Owiti, M.Sc. (KMFRI)

 

Task 2.2. - Non-Compliance in Renewable Resource Systems: A Bait Policy for Sustainable Nile Perch Fishery at Lake Victoria .

We explore whether a sustainable, compliant input can replace a widely used non-compliant input in Lake Victoria's Nile perch longline fishery. The Nile perch fishery is the Lake’s most valuable, with an estimated market value of US$ 842m. However, the fishery is stressed by overfishing and widespread illegal gear use (LVFO 2021). In the last years, longlines with baited hooks have rapidly gained overall prominence as the most common fishing method over gillnets (the alternative method).

Two key challenges undermine the sustainability of the Nile perch longline fishery. First, current regulations focus on hook-size restrictions (larger hooks catch fewer juveniles), despite evidence that hook size does not affect catch outcomes (Gómez-Cardona et al., AWI Discussion Paper Series 2022). Second, at least 71% of fishers use wild-caught bait, which is inexpensive but environmentally harmful and illegal as it is often juvenile fish caught from sensitive wetlands (LVFO 2021).

We study a policy targeting aquaculture bait as an alternative to wild-caught bait. Aquaculture bait can be standardized and regulated through suppliers. It is more sustainable than wild-caught bait and has the potential to improve catch outcomes due to higher quality (Løkkeborget et al., FishRes 2014). For this policy to be viable, two criteria must be met: (1) compliant and non-compliant inputs must have comparable outcomes, making them substitutable; and (2) the complaint input must have sufficient demand at market price, or subsidies can be used to lower compliance costs.

To evaluate criterion (1), we conducted a randomized controlled trial (RCT) with 83 boat owners. Boat owners in the Treatment received 400 units of standardized aquaculture bait. We assessed the outcomes total catch weight, landing value and the probability of zero catch. We hypothesized that aquaculture bait produces outcomes comparable to those of alternative bait, establishing it as a viable substitute. To assess criterion (2), we elicited willingness-to-pay (WTP) for aquaculture bait among 105 boat owners at the same sites using a multi-unit Multiple Price List method. This method, previously applied by Diekert et al. (AWI Discussion Paper Series 2022), provides insights into demand and pricing strategy.

Our results show that aquaculture bait is an adequate substitute for the wild-caught alternative, demonstrated by the lack of significant difference in outcomes between treatment and control groups. Moreover, results indicate that aquaculture bait has potential to be the better performer, especially when used by individuals with better education and experience. Additionally, analysis of the WTP elicitation shows that fishers accept the bait under the presence of a subsidy. A subsidy of 20% creates demand for the aquaculture bait that is equivalent to the demand for the same type of bait (same fish species but mainly wild-caught) that is seen among longline fishers. A subsidy of 40% is needed for a significant uptake on the demand for the aquaculture bait. 

 

Researchers: Sorell de Silva (Ph.D. Candidate), Dr. Santiago Gomez-Cardona, Bwambale Mbilingi, M.Sc. (NaFIRRI), Herbert Nakiyende, M.Sc. (NaFIRRI)

 

Back to Phase 2 Introduction

 

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Above the surface – Surveys and experiments for mental models and acceptance of resilience-enhancing governance

 

WP3 explores how people perceive the governance system and how they behave with respect to different outcomes and in different organizational structures (for example, Beach Management Units (BMU) versus Fisheries Protection Units (FPU) in Uganda). Phase 1 focused on the fishers’ system understanding of the ecological system and factors that influence their fishing behavior (e.g. Klein et al. 2021, Dannenberg et al. 2022). Phase 2 will both refine existing results as well as shift the focus to the governance system. Tools developed in Phase 1 will help identify the role of causality in behavioral response and help map mental models of conservation strategies of the ecosystem. Experimental studies will examine different information scenarios for causal attribution of tipping points and study the interaction of different governance strategies and the willingness of fishers to comply with regulations, esp. size-related regulations. LV is a common pool resource, with different user groups and different interests and views. This is a situation found all over the world in different contexts. A better understanding of the problems and possible solutions will also be helpful for other regions and contexts. 

WP 3.1 – Causes of tipping points in resource systems and user response. 

The Overfishing is a significant environmental challenge that threatens the sustainability of global fish populations and marine ecosystems. While the causes of overfishing are often complex, they are generally attributed to either natural factors, such as climate change and environmental fluctuations, or human activities, such as destructive fishing practices, over-exploitation of certain species, and inadequate fisheries management. Despite growing awareness of overfishing’s detrimental effects, there remains uncertainty about how the perceived cause of the problem influences the behavior of fishers and their willingness to adopt sustainable fishing practices.

This study looks at how understanding the causes of problems like overfishing can influence the decisions fishers make in the future. Specifically, we want to know whether knowing whether a problem, such as a decline in fish stocks, is caused by natural changes (like climate shifts) or human activities (like overfishing) can change how fishers approach their work.  

To address this issue, we will conduct a lab in the field experiment in the fisheries at Lake Victoria in Kenya. With our experiment, we will study whether behavior is different when causal attribution is conducted compared to when it is not and also whether future actions depend on which of the causes, anthropogenic or natural, it is attributed to.
 

Researchers: Dr. Patrick Maus, Horace Owiti, M.Sc. (KMFRI), Prof. Dr. Florian Diekert, Prof. Timo Goeschl, Ph.D.

 

WP 3.2. – Perceptions and maps of mental models of governance.

Task 3.2.1 – Perceptions of fishers towards the declining stocks of Lake Victoria Nile Perch.

A manuscript titled “Perceptions of fishers towards the declining stocks of Lake Victoria Nile Perch” was developed and has been submitted to the Journal of Great Lakes Research. The paper was developed using data from MultiTip phase one in a study that targeted 169 Nile perch fishers drawn from sixteen landing sites in the Ugandan part of Lake Victoria. The study employed mental models and a survey questionnaire.  Results indicate that fishers perceive the use of illegal fishing gear as the primary cause of the Nile perch stock reduction, followed by corruption, overpopulation and poor enforcement of fishing regulations (See Figure 7). The study revealed that the participants believed that they had high levels of control mainly over the use of destructive fishing gears. This underscores the fact that fishers play a pivotal role and should therefore be involved in efforts that are aimed at dealing with illegal fishing practices.

 

Researchers:  Bwambale Mbilingi, M.Sc. (NaFIRRI), Dr. Karlijn van den Broek,  Akumu Joyce (NaFIRRI), Okura Ritah (NaFIRRI), Baluku Johnson (NaFIRRI), Moses Musobya (KMFRI), Fonda Jane Awuor, M.Sc. (KMFRI), Konstantine Odongkara (NaFIRRI), Joseph Luomba, M.Sc. (TAFIRI).

Task 3.2.2 – The Future of Nile Perch in Lake Victoria: Stakeholder Insights on Conservation, Governance, and Socio-Economic Impacts.

 

The Nile perch (Lates niloticus) fishery in Lake Victoria is a cornerstone of East Africa's economy, supporting millions of livelihoods in Tanzania, Uganda, and Kenya. Introduced in the 1950s, it contributes significantly to export revenues, employment, and food security. However, the fishery faces severe challenges, including overfishing, illegal practices, environmental degradation, and climate change, threatening its sustainability and the livelihoods it supports. Overfishing, driven by high demand, has led to declining fish stocks, with fishers reporting reduced catches and smaller fish sizes. Illegal fishing gears, such as undersized nets, exacerbate the problem by capturing juvenile fish and disrupting breeding cycles. The ecological balance of Lake Victoria is also at risk, as the decline of Nile perch could alter biodiversity and increase smaller fish species like haplochromines. The socio-economic impacts of a potential collapse are severe, with thousands of fishers, processors, and traders at risk of unemployment and poverty. 

This study examines stakeholder perceptions in Tanzania, Uganda, and Kenya to inform sustainable management strategies. We explore stakeholder perceptions regarding the likelihood and consequences of a Nile perch stock collapse, as well as identify the governance and conservation strategies considered most effective in addressing this issue. Additionally, this study seeks to assess the effectiveness of current regulations and their enforcement in sustaining the Nile perch population. By examining these aspects, we aim to provide insights into the challenges and potential solutions for the sustainable management of this valuable fishery.

We sampled responses from fishers, fish processor/trader, fish maw collector, law enforcers, policy implementers (at National/ county (or district), policy makers, Civil Society Organization and Researchers in Kenya (N=101), Uganda (N= 102), and Tanzania(N=99). Data was cleaned, structured, and analyzed using ANOVA, Chi-square tests, correlation, and regression analysis. 

Key findings highlight varying levels of concern, perceived risk, and stakeholder involvement across Kenya, Tanzania, and Uganda regarding the potential collapse of Nile perch stocks. Stakeholders in Kenya express the highest level of concern (5 – Very Concerned) and perceive the greatest likelihood of collapse (5 – Very Likely), followed by Tanzania (4.5 concern, 4.2 likelihood) and Uganda (4.3 concern, 4.0 likelihood). Stakeholder involvement is moderate in Tanzania (3), whereas Kenya (2 – Somewhat Involved) and Uganda (2 – Low Involvement) show weaker engagement. Governance effectiveness is rated slightly higher in Tanzania (2.5 – Moderate) compared to Kenya (2 – Slight) and Uganda (1.8 – Low). Income levels vary significantly, with Tanzania reporting the highest average monthly income ($259), followed by Uganda ($81) and Kenya ($67.5). Inferential statistics reveal significant differences in concern levels (ANOVA, p=0.012) and income levels (ANOVA, p=0.005) among the three countries. Correlation analysis shows that concern about fishery sustainability strongly correlates with perceptions of stock collapse (0.65), while higher stakeholder involvement (0.60) is associated with better governance. However, income has a weak negative relationship with concern levels (-0.12), suggesting that wealthier respondents feel less threatened. Regression analysis indicates that stakeholder involvement and governance effectiveness are significant predictors of concern levels, whereas income plays a marginal role. These findings provide valuable insights into the socio-economic and governance factors influencing perceptions of fishery sustainability. 

To enhance the sustainability of the Nile perch fishery, it is crucial to strengthen governance and enforcement of fishing regulations, particularly in Tanzania and Uganda, where governance effectiveness is rated lower. Increasing stakeholder involvement in decision-making can improve conservation outcomes by fostering greater engagement and accountability. Additionally, providing alternative livelihood options for fishers can help reduce dependence on the Nile perch fishery, ensuring long-term economic stability and environmental sustainability.

Researchers:  Fonda Jane Awuor, M.Sc. (KMFRI), Patrick Otuo (KMFRI), Hezron Awandu (KMFRI), Kevin Onsongo (KMFRI), Joseph Luomba, M.Sc. (TAFIRI), Bwambale Mbilingi, M.Sc. (NaFIRRI), Dr. Karlijn van den Broek.

 

Task 3.2.2 – Stakeholder Perceptions, Conservation, and Adaptation Strategies for the Nile Perch Fishery in Lake Victoria.

The collapse of the Nile perch fishery in Lake Victoria has had far-reaching socio-economic and environmental impacts, affecting livelihoods, food security, and fisheries governance. Understanding stakeholders' perceptions of this collapse is crucial for developing effective conservation and adaptation strategies. This study aims to capture these mental models to inform policy interventions that support sustainable fisheries management.

This research seeks to understand how different stakeholders perceive the causes and consequences of the Nile perch fishery collapse, highlighting the various factors they consider most significant. It also aims to explore the key interconnections between socio-economic and ecological factors within stakeholders' mental models, providing insight into how these elements interact. Additionally, the study examines the conservation and adaptation strategies proposed by stakeholders to mitigate the impacts of the collapse, offering potential solutions for sustainable fishery management. 

A mixed-methods approach was used, integrating qualitative and quantitative data collection. The study was conducted across Kenya, Tanzania, and Uganda over three weeks, involving 372 stakeholders (policy makers, law enforcers, boat owners, fishing crew and researchers) randomly selected from Beach Management Unit (BMU) registers. Data collection relied on two digital tools: the M-Tool for mental modeling and the Kobo application for structured surveys. Enumerator training and a pilot study ensured data quality. 

The study's key findings reveal the complexity of stakeholders' mental models regarding the Nile perch fishery collapse. On average, each mental model contained 12.09 concepts and 9.02 connections, with each concept linked to 1.31 others, demonstrating the interconnected nature of stakeholder perceptions. The most frequently identified consequences included loss of livelihood (233 mentions), increased illegal fishing (231), poverty (205), food insecurity (201), and the collapse of the Nile perch industry (182). Centrality measures showed a balanced distribution of influence, with both mean in-strength and out-strength at 1.80, suggesting a well-integrated understanding of socio-economic and ecological factors. These findings underscore the significant socio-economic vulnerabilities associated with the fishery collapse and emphasize the need for integrated policy interventions. A policy approach that incorporates awareness, direct solutions, and integrated management strategies would better align with stakeholder perceptions and prove more effective in fostering sustainable fisheries governance. 

The mental model visualization of Nile perch collapse in Lake Victoria reflects the complexity of stakeholder perceptions by capturing multiple interrelated socio-economic and ecological effects. A policy approach that incorporates awareness, direct solutions, and integrated management strategies would align with stakeholder perceptions and be more effective in fostering sustainable fisheries governance.

Researchers:  Joseph Luomba, M.Sc. (TAFIRI), Fonda Jane Awuor, M.Sc. (KMFRI), Bwambale Mbilingi, M.Sc. (NaFIRRI), Dr. Karlijn van den Broek, Fenant L. Mhagaman (TAFIRI), Kalwa O. Khamis (TAFIRI), Patrick O. Wanguche (KMFRI), Rita Okura (NaFIRRI), Joyce Akumu (NaFIRRI).

 

 

WP 3.3 – Acceptance of and cooperation in governance systems. 

Lake Victoria’s ecological system is highly dynamic, shaped by ecological changes, overfishing, and conflicts among fishers, making resource management complex (Mgaya 2017; Mkuna & Baiyegunhi 2019; Nunan 2010). To address overfishing, riparian states have implemented fisheries regulations and monitoring institutions, which have evolved amid ongoing debates on optimal enforcement structures (Nunan et al. 2015; Mudliar 2021; Nyamweya et al. 2023; Mpomwenda et al. 2022). To examine fishers' preferences for and behavior under different enforcement structures, we conducted a stated choice experiment (Task 3.3.1) and a lab-in-the-field experiment (Task 3.3.2) with Ugandan and Kenyan fishers between May and July 2024. Additionally, we carried out an online experiment with students as a preparatory step for the lab-in-the-field study. 

 

Task 3.3.1 – Fishers’ Preferences for Monitoring Control and Surveillance Systems: A Comparative Study of Kenya and Uganda on Lake Victoria.

 

Effectively managing open-access fisheries remains a significant challenge, especially for shared resources like Lake Victoria. This study examines fishers' preferences and willingness to pay for different Monitoring, Control, and Surveillance (MCS) systems in Uganda and Kenya through a labeled stated-choice experiment. 

The research was conducted at 32 Lake Victoria landing sites, evenly split between Uganda and Kenya, with a total of 768 participating fishers. During the experiment, fishers evaluated four distinct MCS alternatives: a landing-site-based system, a local government-based system, a national government-based system, and a military-based system. These alternatives varied in key institutional features, including detection rates, corruption levels, the election process for enforcers, and landing fees. Fishers made eight choices, selecting their preferred MCS system each time, with the alternatives’ values changing across decisions. 

The findings reveal notable cross-country differences. Fishers in both Uganda and Kenya strongly prefer landing-site-based MCS systems over all other alternatives. However, while Ugandan fishers show no significant preference among the remaining three MCS systems, Kenyan fishers exhibit a clear preference for military-based enforcement over local or national government-led systems. Across both countries, fishers favor reduced corruption, improved detection rates, and directly elected enforcers, though Kenyan fishers demonstrate a significantly higher willingness to pay for these improvements than their Ugandan counterparts. Overall, the study highlights a strong preference for fisher involvement in the monitoring process. However, preferences differ between the two countries: Ugandan fishers favor the involvement of landing-site management in the MCS process, while in Kenya, the effectiveness of enforcement mechanisms plays a more critical role.   

 

Researchers: Fonda Jane Awuor, M.Sc. (KMFRI), Bwambale Mbilingi, M.Sc. (NaFIRRI), Pia Pico (Ph.D. Candidate), Philipp Händel (Ph.D. Candidate), Prof. Dr. Astrid Dannenberg.

 

Task 3.3.2 – Intergroup differences in cooperative and punitive behavior: A cross-country analysis of fishers at Lake Victoria.

 

Preventing the overexploitation of Lake Victoria’s fish resources requires both cooperation among fishers and effective sanctioning mechanisms. However, intergroup conflicts, such as those between Nile Perch and Dagaa fishers, can shape cooperative and sanctioning behaviors. This study explores these dynamics through a lab-in-the-field experiment conducted with Nile Perch and Dagaa fishers in Uganda and Kenya. It examines whether fishers targeting different species cooperate and punish each other differently than those targeting the same species and whether formalizing punishment can reduce this bias.

Conducted alongside Study 1, this experiment included 384 Ugandan and 384 Kenyan fishers. The experimental design varied group compositions, with fishers participating in public goods games either with a peer targeting the same fish species (ingroup) or one targeting a different species (outgroup). Additionally, the nature of punishment institutions was manipulated. Under informal punishment, fishers could directly penalize their peers after observing their contribution decisions. Under formal punishment, fishers first established a punishment strategy for all possible contribution levels, then learned about their peer’s strategy before making the contribution decision.

To test the experimental design, we conducted a preliminary study with German students from two universities. In this sample, cooperation did not differ based on whether individuals interacted with an ingroup or outgroup member. However, a clear bias in punishment emerged, with students punishing outgroup members more harshly than ingroup members under informal punishment. 

The results at Lake Victoria reveal distinct regional differences. Unlike the student sample, Ugandan fishers display a clear bias in cooperation, exhibiting stronger cooperation within their ingroup than with outgroup members. However, this bias disappears under informal punishment and reverses under formal punishment, driven by a sharp decline in ingroup cooperation. Additionally, Ugandan fishers punish those targeting the same species more harshly than those targeting a different species, but this pattern is observed only among fishers who perceive conflicts between target species and only under informal punishment. In contrast, in Kenya we do not find that fishers with different fish species cooperate or punish each other differently than fishers targeting the same species. These findings highlight key differences in group dynamics between Nile Perch and Dagaa fishers in Uganda and Kenya and suggest that formalizing punishment does not mitigate the impact of group dynamics on cooperative behavior in Uganda.

 

 

Researchers: Prof. Dr. Astrid Dannenberg, Pia Pico (Ph.D. Candidate)

 

Back to Phase 2 Introduction.

 

 

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