Stimulating investment in pearl farming in ... - World Fish Center

Suitability of Habitats for Growth of Black-Lip and Silver-Lip Pearl Oysters Final, June 20083.0 ENVIRONMENTAL CONDITIONS AT EXISTING PEARLFARMS3.1 Black Pearl Farms3.1.1 AustraliaThere is an emerging black pearl industry in the Abrolhos Islands and in Shark Bay, WesternAustralia based primarily on the supply of juvenile pearl oysters from hatcheries (AustralianAquatic Portal 2007). In Queensland, suitable-sized wild black-lip pearl oysters collected bythe East Coast Pearl Fishery are translocated to aquaculture farms in Queensland and theTorres Strait for use in pearl production, but these comprise only a small amount of the liveshells used for pearl production (Department of Primary Industry and Fisheries,Queensland 2007).3.1.2 Cook IslandsBlack-lip oysters are currently farmed in Manihiki, Penrhyn (Tongareva) and Rakahangaatolls in the northern Cook Islands (Cook Islands Government, 2007). This species occursnaturally in the larger lagoons of Manihiki and Penrhyn, but was introduced intoRakahanga (Sims 1994). The physical features of Manihiki Atoll and its lagoon have beenwell documented, but relatively little is known about Penrhyn and Rakahanga atolls. Thecharacteristics of various atolls in the Cook Islands are summarised in Table 1 and discussedbelow.Manihiki is a small pear-shaped atoll with two large islets to the north-east and west andmany small islets in the south (Wells and Jenkins 1988). The lagoon is about 5 km indiameter and has a maximum depth of 72 m. The lagoon has a raised outer rim, whichpermits only minor water exchanges between the lagoon and the surrounding oceans,except during significant wave events. The reef flats between the small islets surroundingthe lagoon are generally less than 1 m deep (Sharma et al. 2001). The outer reef has a typicalmorphology with buttresses, surge channels and deep water close in (Bullivant 1974 in Wellsand Jenkins 1988). The greatest development of coral is found at the south-east perimeter ofthe lagoon, where the waves wash over the reef. The pinnacles within the lagoon arecomposed of living and dead coral. The islets within the lagoon are surrounded by smallfringing reefs. Ponia et al. (2000) estimated that the lagoon, land, coral and reef componentsof the atoll had surface areas of 48.0, 9.8, 5.0 and 1.1 km 2 , respectively. They also estimatedthat 25.3 km 2 of the lagoon lay at depths of 10-30 m and could be used for pearl farming, butnoted that only 7.7 km 2 of the lagoon was being used for this purpose in 1999.Penrhyn, the second most important area for pearl production has the largest lagoon in theCook Islands surrounded by reef and many islets and has three large passages at itsnorthern end. The lagoon, land, coral and reef components of this atoll have surface areas of208.0, 9.8, 15.0 and 1.1 km 2 , respectively (Ponia 2000). Rakahanga Atoll is small, with a totalsurface area of 4.0 km 2 . The lagoon is surrounded by coral reefs and has two main islets tothe north and south and seven smaller islets between these (Wells and Jenkins 1988).3.1.3 FijiThe largest black pearl oyster farm is located in Savusavu Bay (Islands BusinessInternational 2007). There are other smaller farms on Savusavu, Taveuni, Nakobo, MaliThe Ecology Lab Pty Ltd – Marine and Freshwater Studies Page 7