Indonesia's Lombok Fishers Revive Crab Stocks Through Community-Led Mangrove Silvofishery

On the east coast of Lombok Island, Indonesia, local fishers facing dwindling mud crab populations have launched their own mangrove planting programme, integrating forest restoration with crab cultivation in a practice known as silvofishery. The initiative is restoring habitat, raising earnings, and providing a locally driven model for reconciling aquaculture with coastal ecosystem recovery in one of Indonesia's most economically vulnerable districts.

 

Community Origins and the Decline of Wild Crab Stocks

 

The silvofishery initiative in Sugian village grew from direct observation of declining crab abundance. Fishers who had long set traps in the estuary for wild mud crabs of the genus Scylla found populations falling as overfishing removed juveniles and undersized animals before they could contribute to reproduction. Jamil, a 63-year-old fisher who now runs a silvofishery pond, described the old dynamic plainly. Selling crabs immediately when small fetched a lower price, yet the short-term incentive to do so was strong. When populations dropped and earnings followed, the community began looking for an alternative that could support both livelihoods and the natural system that underpinned them.

 

Ecological Logic of the Silvofishery

 

Mud crabs are ecologically distinctive because they thrive in the turbid, sheltered conditions that mangrove ecosystems provide. Mangrove roots trap sediment, reduce water flow, stabilise temperatures, and support the microorganisms and nutrients on which the crabs depend. Herman, who leads the local community fishing organisation in Sugian, has noted that the crabs prefer murky, dense water and are not suited to the high-visibility conditions of open aquaculture ponds. The relationship is reciprocal, as the crabs dig holes that aerate sediment and cycle nutrients, which in turn supports mangrove health. The silvofishery arrangement attempts to formalise and protect this mutual dependence by combining deliberate mangrove planting with crab cultivation in the same managed areas.

 

Economic Context and Social Pressure

 

The economic conditions driving the search for sustainable livelihood alternatives in East Lombok are stark. The district topped Indonesia's list of more than 500 districts for the highest number of residents who left for work overseas last year, with approximately 14,000 people, around one percent of the district's population, receiving permits to work abroad in a single year. Mothers typically become domestic workers in the Middle East while fathers leave for ship crew positions or plantation labour in Malaysia, separating families under financial pressure. The minimum wage set by the local government is 2.7 million rupiah per month, equivalent to approximately US$150 and less than half the Jakarta minimum. For communities like Sugian, a more productive and sustainable crab fishery represents not just an environmental gain but a direct mechanism for reducing the economic forces that drive family separation.

 

Mangrove Planting and Cultivation Methodology

 

In Sugian, fishers established belts of mangrove seedlings around pond embankments, inlets, and corners, adapting their methods over time to reinforce young trees against tidal washing. The approach has been developed largely through trial and error in the absence of formal technical support or extension services. Jamil raises crabs to adulthood alongside the newly planted mangroves rather than selling juveniles immediately, a practice that generates a higher price per animal and supports a more sustainable population. His wife, Eli Ernawati, sorts the catch by size and destination for sale to traders and direct customers, with earnings sufficient to cover household needs on productive days.

 

Read more: The Biggest Threats to the Ocean

 

Indonesia's Mangrove Context and the Broader Challenge

 

Indonesia hosts approximately 3.3 million hectares of mangrove forests, the largest estate in the world, yet studies indicate that up to 40 percent has been degraded or cleared, with crab, fish, and shrimp cultivation emerging as the major driver of deforestation since the 1980s. A government pledge to plant 600,000 hectares of mangroves by 2024 achieved only a fraction of its target. The silvofishery practised in Lombok represents a locally driven response to one of Indonesia's most enduring environmental dilemmas, namely how to support aquaculture-dependent livelihoods while restoring the coastal ecosystems on which those livelihoods ultimately depend. Indonesia's aquaculture exports were valued at US$5.5 billion in 2021 according to the Food and Agriculture Organization, underscoring the national economic significance of the sector.

 

Limitations and the Need for Technical Support

 

Despite the promise of the mud crab silvofishery model, local officials are clear that limited access to extension services and technical training leaves most farmers to refine their methods through personal experimentation rather than formal instruction. Nurrahman, a fish farmer in Sugian, has called for guidance to reduce the risk of failure that farmers currently bear alone. The challenge has been compounded by governance reforms introduced in 2014 that transferred authority over coastal waters from district administrations to provincial governments, creating a mismatch between local need and the institutional proximity of the agencies responsible for fisheries support. Mastur, head of the East Lombok fisheries agency, has attributed part of the difficulty to this governance shift, which moved responsibility for coastal areas up to 12 nautical miles from shore to the provincial level.

 

Applicability Beyond Mud Crabs

 

Officials and researchers note that silvofishery is not a universal solution for the broader aquaculture sector. The open-water characteristics of mangrove environments that benefit mud crabs create problems in enclosed shrimp farming systems, where fallen mangrove leaves decompose rather than fertilise. Research conducted in 2022 at a recently planted mangrove forest in Brebes district on Java found that healthier mangroves supported mud crab populations, providing scientific support for the approach specifically in the crab cultivation context. The implication is that targeted expansion of silvofishery in areas with suitable species and habitat conditions could meaningfully extend both mangrove coverage and crab productivity, while broader aquaculture decarbonisation and restoration strategies will require different approaches for different species and production systems.

 

Implications for Coastal Food Security and Livelihoods

 

The Lombok silvofishery illustrates how community-led ecosystem restoration and fisheries management can be mutually reinforcing when the ecological logic of the approach is well matched to the species and habitat involved. The head of West Nusa Tenggara's fisheries department, Muslim, has articulated the core principle that if the habitat is good, the crabs will return, and that cultivation must therefore include restoration of the natural environment. For subsistence communities in East Lombok and similar coastal areas across Indonesia, the ability to derive higher and more stable earnings from a restored fishery without destroying the habitat that sustains it represents one of the more practical pathways to long-term food security and economic resilience.