There is a strong worldwide demand for trochus shell. Most of the shells collected in the Kimberley region are currently sold through Perth at a wholesale price of about $9.50 per kg. Some of the Aboriginal groups are value-adding this product by polishing trochus shells for ornaments which sell for $20 to $50 apiece. Recent interest has also been expressed on the processing and export of trochus meat which is known to fetch a high price in Japan. Trochus attract a lower market price than warm temperate abalone, and the more intensive, land or sea-based systems for farming abalone are unlikely to be profitable with trochus (Maguire, 2001). Enhancement of depleted reef fisheries is a more promising strategy. ResearchResearch on trochus in Western Australia in the early 1990s has led to recent interest in aquaculture of the species by the Bardi Aboriginal community at One Arm Point and other communities in the Kimberley. From the success of trochus reseeding research work, there appears to be significant potential for increasing and sustaining the annual harvests of wild trochus through stock enhancement using cultured juveniles. The Department of Fisheries has conducted research, through joint funding with ACIAR, on the benefits of mass-release of juveniles (1-4mm) on reefs in the Kimberley (Purcell & Lee, 2001). This work provides information for commercial-scale marine ranching of trochus. The aim is to allow juveniles to grow to breeding size and further replenish trochus stocks. An alternative or complementary approach is to transfer broodstock to reefs with depleted populations. The KAAC's Multi-Species Hatchery in Broome is set to supply Aboriginal groups which hold aquaculture licences with trochus juveniles to seed onto reefs in the Kimberley region in 2001. The restocking program is promoted by the KAAC through funding provided by ATSIC and WA State Government. | Methods for Enhancing Trochus Fisheries | - Relocation of broodstock to areas with few trochus. (Fishing for these broodstock must be discouraged.)
- Releasing large numbers of small hatchery-produced juveniles. (Losses to predators are a major risk.)
- Release of large juveniles after an extended nursery phase in cages on reefs. (Major risks are high costs, insufficient food supply and storm damage to cages.)
The most appropriate method depends on local conditions. Success can be variable and this may depend on the biological and physical characteristics of individual reefs. In general, all of these methods require a long-term change in fishing strategy, involving sustainable management, so that enhanced reefs are not subsequently overfished. |
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