Community-based management of the Terubuk fishery in Riau, Indonesia.

• Directorate General of Fisheries, Indonesia

The terubuk (Tenualosa macrura) is an economically and culturally important fish for coastal communities in Riau Province of Sumatra, Indonesia. This project built on the earlier research of a small ACIAR project, which established that stocks of this species were severely depleted, with over-fishing and low water quality identified as the key contributing factors to low terubuk catches. Over-fishing was especially severe because the fishers concentrated on spawning grounds in order to capture the gravid females, prized for their eggs. A major water quality issue concerned the high volumes of sawdust occurring in areas where terubuk live.

The two major issues to be resolved in order to finalise management measures were: 1) an accurate definition of the spawning areas that may need protection; 2) the socioeconomics of how any management measures may impact on local communities and other stakeholders.

An appropriate strategy for the management of the terubuk fishery resource had to include coastal community participation and be based on information covering the biology and economics of the fishery, its socio-cultural aspects, and the socio-economic characteristics of coastal communities. Possible strategies for conserving and managing the terubuk fishery resource could include controlling fishing effort and controlling the release of sawdust from sawmills into the Siak River. This could result in, at least temporarily, some unemployment or temporal closure of key spawning areas. Therefore, the extent to which the community depended on terubuk and alternative income sources had to be understood, and this could only be obtained through a comprehensive consultative process with all stakeholders. Such a process would produce a management plan that led to effective conservation of the Terubuk fishery.

The major objective was to work with all stakeholders of the terubuk fishery - fishers, fishing communities, fisheries management, NGOs and sawmill operators - to develop an overall management plan to ensure the survival of the fishery, then as stocks recovered to encourage its expansion to a sustainable level, without creating undue hardship for any of the stakeholders.

The researchers sought to understand all relevant socio-economic aspects of the terubuk fishery. They compiled descriptions of the larval distribution of terubuk in order to evaluate options for potential spatial or temporal closures for management and conservation. They worked with sawmillers and sawmill companies to identify ways to minimise the release of sawdust into the rivers and develop new ways of using sawdust to their economic advantage.
Finally, in close consultation with all relevant sections of the community and based on evaluation of options utilising both socio-economic and biological knowledge, they formulated policies for managing the terubuk fishery.

A plankton sampling program was conducted at 17 stations where terubuk were known to occur, to describe the distribution and abundance of terubuk larvae and better define spawning areas. These included 11 sites in the sheltered coastal straits inside Bengkalis Island and six sites in the Siak River, which drains into the coastal waters. The most notable feature was that larvae of terubuk and all related types were in very low numbers in the terubuk spawning grounds - indicationg that the targeted fishing of pre-spawning aggregations may be leading to recruitment failure.
Wood waste material in the waterways caused some terubuk to die before spawning and reduced the number of viable larvae, thus reducing the total population. Terubuk are filter feeders and cannot choose their food - they filter out any small material that is about the same size as their natural food (plankton). Small wood particles about the size of sawdust constituted up to 80% of the stomach contents of terubuk. The fish cannot digest large amounts of woody material, thus leaving too little space in the stomach for plankton - poor nutrition caused terubuk at all growth stages to be thin. The survivors may be less able to accumulate enough fat to change from (male) pias to (female) terubuk, and the females may not accumulate enough fat to produce large numbers of viable eggs.
The scientists concluded that banning gillnets in the spawning areas during the spawning periods was necessary, urgent and indispensable, as terubuk could not be restocked from a hatchery. They presented their conclusions to a meeting of key decision-makers and stakeholders.
The Indonesian participants accepted all the project recommendations, but at the Final Project Coordination Meeting the scientists reminded those present that none of the recommendations agreed to in late 2001 had yet been implemented. Terubuk populations continued to decline and it was urgent to close the spawning grounds to gillnets under 7 inches. The stakeholders resolved to take action.
Since 1999-2000 much of the forest resource of the Province has gone, and sawmilling has either ceased or is a greatly reduced activity. Hence the amount of sawdust produced and disposed of into the water has declined. Actions now revolve around preventing old sawdust from leaching into waterways and the control of dumping other woody wastes.