Mangrove forest provides enormous benefits to humanity, especially as essential place for biodiversity, as protection against the destructive power of waves (reducing erosion), and as nurseries for coastal and offshore fisheries worldwide. Among other benefits, mangrove forest serves as highly effective carbon stores and sinks. It produces large quantities of leaf material that becomes the basis for a detritus food web. They also help to build or maintain elevation in the face of rising seas.

In spite of these documented ecological functions, mangrove forests in Indonesia have been degraded and filled for decades to provide other coastal uses, like ports and housing. A report says that conversion of mangroves for coastal aquaculture is the foremost driver of mangrove loss. An estimated 38% of Indonesia mangrove loss can be attributed to the clearing of mangroves for shrimp culture, while another 14% can be blamed on other forms of aquaculture. Moreover in Bali, local people have cut mangroves to take the leaves as food for livestock sin 1980. For Balinese, mangroves provide rot resistant, high value timber and excellent fuelwood which has been harvested since long time ago.

It is not surprising then that attempts to restore mangroves often fail to achieve the stated goals or fail completely because of direct impact to economic activities of man still persist. However, such large-scale conversion has been sparking negative environmental impacts, including collapses in wild fisheries. The socio economic impacts of this conversion have been tremendous in regions where fishing in and around mangroves is a critical activity providing food and income for local people.

Fortunately, there is now a growing awareness of the importance of mangroves and government and community-led efforts are under way to restore and preserve mangroves. Losses are being driven by a suite of other human threats as well, however, including over-harvesting and deforestation agricultural, urban and industrial runoff oil spills and poorly managed dredging and coastal development.

The innovative idea is connecting mangrove preservation to increment of economic activity. Properly speaking, the preservation has to give direct economic income to local people. Specific examples of the economic value of healthy mangroves include crabs and fishes harvested in Mangrove Ecotourism-Kampoeng Kepiting, Bali. Here, the fisheries never converse forest into large scale crab and fish culture but rather use the mangrove forest as aquaculture media. Such a commmercial offshore crabs fisheries are also highly dependent on mangroves as nursery or breeding grounds. Further, local community has succeeded create chocolate from Pidada fruit, one of mangrove species. The more mangroves are preserved, the more the crabs and fishes can be harvested.  Only non-destructive forestry, fishing, and aquaculture practices are permitted. The local people get income five times as much as before this sustainable fisheries are implemented.

This case provides evidence that mangrove forests can be conserved and enjoyed while still providing reliable long-term but reasonably high economic return for local and larger communities. It shows that when well-managed, mangroves can ensure sustainable yields of products. Without mangroves, coastal erosion is widespread and beaches are continuously being replenished artificially, a very expensive venture. 

Source: 

http://www.mongabay.co.id/2014/10/03/menjaga-hutan-mangrove-teluk-benoa-ala-nelayan-wanasari/

Lewis III, Roy R. (2001). Mangrove Restoration - Costs and Benefits of Successful Ecological Restoration. In review, Proceedings of the Mangrove Valuation Workshop, Universiti Sains Malaysia, Penang, 4- 8 April, 2001. Beijer International Institute of Ecological Economics, Stockholm, Sweden.