Policy Insights and Implications

One of the main successes of MultiTip is our ability to provide insights on the governance of the socio-ecological system (SES) of Lake Victoria. We are also able to analyse tools in fisheries management that can increase the resilience of the resource system.

Boats on the shores of a natural harbour at Lake Victoria.

We focus on three areas of research with regards to governance and improving the resilience of the resource system: a conservation policy that could leverage the spatial dimensions of Lake Victoria, the impact of fishing gear regulations and the use of compliance subsidies in fisheries management.


Leveraging the Lakes Features

Impact of Gear Regulations on the Nile Perch Stock

Compliance Subsidies as Novel Regulatory Instruments 


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Leveraging the Lakes Features

The spatial dimensions of Lake Victoria, i.e. size and circular shape, means that boats do not fish far from land and its shallowness implies that fish stock density is high in areas that are not exploited by fishers (Gómez-Cardona, 2022; for more on the lakes spatiality , click here). Given these findings, MultiTip assess a policy that leverages the features of the lake for fisheries management (Gómez-Cardona, 2022). The policy declares the central areas of the lake as reserves and thus, it takes advantage of the already existing hurdle to reach areas that are both far from the shore and where fish density is relatively higher. While not a first-best policy, we find that the policy reduces costs in patrolling activities, which benefits and leverages the higher costs of reaching reserved areas. It reduces the variance in the SES as it is perturbed by external factors, e.g. prices, and hence, it increases the resilience of the SES to external shocks.

Principal Investigator: Dr. Santiago Gómez-Cardona

Publication: Gómez-Cardona, S., 2022, Spatial Structure effects on Fisheries Management for Lake Victoria’s Nile Perch. AWI Discussion Paper 713, Heidelberg University



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Impact of Gear Regulations on the Nile Perch Stock

The Lake Victoria Nile perch fishery is a de facto open access fishery and the existing methods of regulation rely on defining legal catch sizes and enforcing the minimum legal size of nets mesh sizes and hook sizes (LVFO, 2016). There is an open discussion about the specific merits of using enforcement to achieve compliance (Cepić and Nunan, 2017; Obiero et al., 2015). Although this is extremely important, it should be complemented with an analysis on the effectiveness of these regulations in achieving the desired effect on the fishery.

We examine the impact of gear selectivity of gillnets and longline hooks on the resilience of the Nile perch population. We use data from the Catch Assessment Survey from 2005 to 2015 (LVFO, 2015) which provides information on catch and gears used. We then use this information on gear selectivity to estimate overall fishing selectivity of the fleet. Our analysis provides evidence that a gill net fishing fleet is capturing increasingly larger fish and this trend correlates with increased enforcement of the mesh size regulation. The hook fishing fleet, by contrast, is not experiencing any changes in the average size of the fish capture. This is despite increasing use of undersized hooks (Aloo et al, 2017). Overall, the evidence suggests that gill-net mesh size regulation is effective in protecting juvenile fish stock while the hook size regulation appears to miss its intended effect.

Policy Fig1
(Click to enlarge)
Comparison of empirical catches from Gillnets (left) and Hooks (right) of different sizes. The y axis refers to the total amount of individuals in the sample used to generate the graphs. The differential height of the data coming from different size classes within each gear is due to the differential numbers of fish at each size and the differential number of boats at each gear size-class that are recorded in the dataset.Source: Gómez-Cardona et al., 2022

Researchers: Prof. Timo Goeschl, Ph.D., Prof. Dr. Anna Marciniak-Czochra, Dr. Santiago Gomez-Cardona, Johannes Kammerer (Ph.D. Candidate)

Partner: Hillary Mrosso (TAFIRI)

Publication: Gómez-Cardona, S.; Kammerer, J. and Mrosso, H. 2022. Fishing Fleet Selectivity in Lake Victoria. AWI Discussion Paper 712, Heidelberg University.



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Compliance Subsidies as Novel Regulatory Instruments

The current governance of Lake Victoria’s resource system relies on a coercive regime favouring direct enforcement (LVFO, 2016). In theory, this deters illegal gear use as fishers consider the probability of detection and punishment. However, in reality, this method leads to sporadic, but harsh enforcement that generates limited deterrence at high cost, destroys assets (boats and gear, some of it legal) and regularly leads to fatalities among both fishers and enforcers (Kolding et al., 2014; Obiero et al., 2015; Cepić and Nunan, 2017).

MultiTip studied regulatory alternatives to the current approach. We do this by testing the effect of a norm-nudge assisted subsidy program on demand for legal fishing nets in the Dagaa (silver cyprinid) fishery at Lake Victoria (Diekert et al., 2022). We run a field intervention at 20 landing sites in Tanzania and study two main research objectives. First, we study fishers willingness to pay for legal fishing nets with which we can assess the consistency of demand with a high prevalence for illegal fishing nets and what discount is necessary for widespread demand of legal nets. Second, we study a non-price related intervention in the form of a nudge that provides information on the desirable behaviour of peers. Therefore, we can analyse how the nudge affects the cost-effectiveness of the subsidy

Our findings suggest that subsidies on legal gear have the potential to drive out illegal gear at acceptable cost. Our evidence also suggest that soft measures like nudges that appeal to ‘good fishing practices’ are ineffective. This field experiment provides a first proof-of-principle regarding the feasibility of compliance subsidies on legal fishing gear as a novel tool in fisheries management.

Policy Fig2
(Click to enlarge)
The average number of panels demanded at all offered price points (left plot) and in terms of the different discounts offered (in ranges of 10%) compared to the average reported market price (right plot). The graphs are split by baseline and treatment group (combined N = 247).

Principal Investigators: JProf. Dr. Florian Diekert , Dr. Tillmann Eymess , Prof. Timo Goeschl Ph.D., Dr. Santiago Gómez-Cardona

Partner: Joseph Luomba (TAFIRI)

Publication: Diekert, F., Eymess, T., Goeschl, T., Gómez-Cardona, S. & Luomba, J. (2022) Subsidizing Compliance: A Multi-Unit Price List Mechanism for Legal Fishing Nets at Lake Victoria. AWI Discussion Paper 0711, Heidelberg University.



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Aloo, P. A., J. Njiru, J. S. Balirwa & C. S. Nyamweya, 2017. Impacts of Nile Perch, Lates Niloticus, introduction on the ecology, economy and conservation of Lake Victoria, East Africa. Lakes and Reservoirs: Research and Management 22: 320–333.

Cepić, D. and Nunan, F. (2017). Justifying Non-Compliance: The Morality of Illegalities in Small Scale Fisheries of Lake Victoria, East Africa. Marine Policy, 86:104–110.

Kolding, J., Medard, M., Mkumbo, O., and van Zwieten, P. (2014). Status, trends and management of the Lake Victoria Fisheries. Inland Fisheries Evolution and Management—Case Studies from Four Continents. FAO Fisheries and Aquaculture Technical Paper, 579

LVFO (2015). Regional catch assessment survey synthesis report. june 2005 to november/december 2015. hydroacoustics regional working group. Lake Victoria Fisheries Organization, Technical Reports.

LVFO (2016). Fisheries management plan III for Lake Victoria fisheries 2016-2020.

Obiero, K.O., Abila, R.O., Njiru, M., Raburu, P.O., Achieng, A.O., Kundu, R., Ogello, E.O., Munguti, J.M., & Lawrence, T.J. (2015). The challenges of management: Recent experiences in implementing fisheries co-management in Lake Victoria, Kenya. Lakes and Reservoirs: Research and Management, 20, 139-154.


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Updated on: 12.08.2022
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