Case Study

Madang Reef Fish Fishery (Papua New Guinea)

Author: Jacqueline Lau


This case study demonstrates how adaptive customary management confers resilience to key habitats, stock and social benefits in the face of fishing pressure and (hypothetically) climatic shocks through learning, agency, and flexibility. However, biomass is declining and previously successful adaptive management alone may not confer long-term resilience in the face of combined climate change effects and increased fishing pressure.

Fishery Background

The fishery encompasses two neighbouring coastal communities on KarKar Island, Madang Province, Papua New Guinea. Both communities pursue mixed-livelihoods, including fishing and cash crop and subsistence farming. Beside each community is a coral reef on a steep slope, which supports a mixed species coral reef fishery. 

The fishery is governed at a local level, allowing the communities to make quick adaptive decisions. Clan leaders provide strong leadership in the fishery. They lead the communities in continuing traditional rotational closures, and ensuring a balance of ecological and social outcomes from the fishery. Decisions are made through a combination of participation from the community and top-down from clan leadership. 

The fishery is small and local. Most fish are for subsistence, though some are sold locally. The fishery itself has very little influence on broader markets, and there are no economic incentives or penalties related to climate change. There are also very limited economic resources available to assist with adaptation.

Climate Change and Resilience

There are few granular and long-term projected climate shocks for this case study, but more broadly, PNG is expected to experience sea-level rise, increased air and sea-surface temperatures, and ocean acidification. The fishery has not experienced any distinct shocks over the past 20 years.

Key resilience features of the fishery include: 

1) strong, legitimate and effective local governance;

2) strong social capital;

3) well-defined boundaries based on clan sea-tenure;

4) a strong historical system of adaptive management and iterative learning;

5) a degree of socio-economic diversity in the fishery, with cash and subsistence crops also important for livelihoods and

6) moderate ecological connectivity, modularity and diversity. 

These features, and especially the adaptive strategies based on local-environmental knowledge, their legitimacy—based in strong leadership, participation governance, and strong social capital—and the moderate ecological diversity of the fishery, are well placed to continue to confer some resilience in the face of climatic shocks.

To date, the customary management system has conferred resilience to local fishing pressure. It is well placed to navigate trade-offs between the social and ecological dimensions of resilience through processes for translating local environmental knowledge and local monitoring into socially-accepted management measures (Lau et al., 2021). Overfishing is mediated by customary periodic closures, which act as buffers. However, there’s a broad trend of biomass decline suggesting that these closures are becoming less effective (Cinner et al., 2019). Thus, while the customary management process is capable of implementing measures for resilience in a timely fashion, it may be less capable of designing new features beyond temporary and rotational closures.

In sum, combined changes to the broader socio-ecological system (i.e., combined climate change impacts on the fishery, alongside subsistence and cash crops) may prove a challenge for existing resilience attributes to continue to confer long-term resilience.


Cinner, J. E. et al. (2019) ‘Sixteen years of social and ecological dynamics reveal challenges and opportunities for adaptive management in sustaining the commons’, PNAS, 116(52). doi: 10.1073/pnas.1914812116.

Lau, J., Gurney, G. and Cinner, J. (2021) ‘Environmental justice in coastal systems: Perspectives from communities confronting change’, Global Environmental Change, 66(102208).

Photo: Net fishing in Papua New Guinea. © Dean Miller