Hatchery production and restocking of sandfish in community-managed fishing rights areas (qoliqoli), Fiji Islands (09/2008)
Thursday, 25 September 2008 00:00

 

By Cathy Hair and Tim Pickering

Sea cucumbers are valuable but severely depleted fisheries throughout Pacific Island countries and territories (PICTs), and Fiji is no exception.  In Fiji, dairo (or sandfish, Holothuria scabra) is an important sea cucumber species that also forms part of the Fijian traditional diet, so it contributes to food security in addition to being a lucrative export commodity. In the last 20 years, fishing pressure — stemming from export demand — has resulted in declines in size and abundance of individuals of this accessible shallow-water species.

 

 

Sandfish hatchery technology has been developed in New Caledonia and in Australia through research supported by the Australian Centre for International Agricultural Research (ACIAR) and the WorldFish Center. Techniques to spawn sandfish and rear larvae up to juvenile size (>3g) are now relatively straightforward, and can be transferred to other PICTs. On-growing juvenile sandfish to larger sizes in tanks is not feasible however, because feed and space quickly becoming limiting factors.  Release into large ponds or into the coastal environment is necessary for growing juveniles to commercial size.

 

The major research question yet to be convincingly answered is whether post-release survival of sandfish, and growth to harvestable size, are sufficient to justify the cost of breeding and rearing juveniles in captivity. Pilot studies by the WorldFish Center and other agencies demonstrate that sandfish re-stocking results are very unpredictable, and the benefits are uncertain. More releases of larger numbers of juveniles, with rigorous post-release monitoring, are necessary to provide baseline growth and survival information. Field experiments will then be needed to further refine release protocols and habitat selection criteria to obtain the best results.

 

The ACIAR project “Development of aquaculture-based livelihoods in the Pacific Islands region and tropical Australia” — led by James Cook University with project partners SPC, WorldFish Center and Univeristy of the South Pacific — funds aquaculture research “mini-projects”.  These are small, targeted research interventions to address bottlenecks or constraints to sustainable aquaculture development. 

 

The mini-project “Culture of juvenile sandfish, Holothuria scabra, for re-stocking and sea ranching trials in Fiji” was launched in May of this year. A stakeholder’s consultation was held with country partners Fiji Ministry of Primary Industries (Department of Fisheries), Hunter Pearls, and the Fiji Locally Managed Marine Area Network (FLMMA), to define objectives and protocols for a juvenile sandfish re-stocking and sea ranching project in Cakaudrove Province on Vanua Levu. 

 

This mini-project will transfer sandfish hatchery technology to Fiji, then will scale-up and extend earlier re-stocking research on post-release survival and growth. Some preliminary work will also be done to determine possible management frameworks for large-scale sandfish re-stocking and sea ranching that will meet the future needs of stakeholders.

 

The term “sea ranching” here means a “put, grow and take” operation, whereby owners harvest released sandfish from a lease or property rights area (e.g. qoliqoli) as a commercial operation.   “Re-stocking” means to restore breeders in a depleted fishery by releasing sandfish into a restricted area and protecting them as a future spawning population. This latter activity is best combined with community-based marine resources management tools such as marine protected areas (MPAs).

 

Following the launch of this mini-project, the next task is to identify suitable environments and communities for re-stocking trials. Collaboration with Fiji’s Department of Fisheries and with selected communities in Cakaudrove Province is ongoing, and is aimed at finding the best possible juvenile release sites to increase the chances of success. WorldFish Center research has shown that seagrass beds comprising ribbon-like seagrasses on sandy-muddy substrates and growing at a depth of not less that 20 cm at low tide, are the most suitable. 

 

Surveys must also be done to determine the most reliable sources of adult sandfish to use as broodstock for the hatchery production of juveniles, which will take place at the Hunter Pearls hatchery at Savusavu from November 2008–February 2009. During this hatchery phase, staff of Fiji’s Department of Fisheries and Hunter Pearls will be trained in sandfish breeding and larval rearing techniques.

 

Afterwards, sandfish will be released and monitored to track their progress. Rigorous sampling and statistical techniques are necessary to make sense of the high variability inherent in this type of survey data. An ACIAR-USP masters scholarship has been awarded to a Fijian student to lead the survey work. Access and management arrangements for this research and monitoring phase will be made with a custodian community at each site because, as the sandfish grow in size and value, security will become an issue. For example, communities who already delineate and enforce an MPA in their fishing rights area will be preferred for this research.

 

There are conflicting views about whether re-stocking or sea ranching sandfish can actually be successful. It is only through open, transparent and research-based approaches that stakeholders can gain the information they need to plan for the long-term health of the region’s sandfish resources. The Fiji sandfish mini-project is intended to be the next step along this path.