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The Silverlip Pearl Oyster is the largest species in the pearl oyster family. It also produces the largest pearls. Australia has three stocks of Silverlip Pearl Oyster, all of which are sustainable. 

Pinctada maxima or the Silverlip Pearl Oyster is the largest species in the pearl oyster family [Shirai 1994] and produces the largest pearls. It is distributed within the central Indo-Pacific region, bounded by the Bay of Bengal to the west, Solomon Islands to the east, Taiwan to the north, and Northern Australia to the south [Southgate et al. 2008], at depths from the shallow sub-tidal to more than 50 m. Within Australia, the population genetic distribution has been investigated in Western Australia and Northern Territory [Benzie et al. 2006]. The biological stock structure is uncertain; however, Western Australian stocks are generally considered to be one stock (with the possible exception of a localised population in Exmouth Gulf), separate from stocks in the Northern Territory. The biological stock structure for Queensland is unknown.

Here, assessment of stock status is presented at the jurisdictional level—Western Australia, Northern Territory and Queensland.

Queensland

The Pearl Fishery (Queensland) is a small-scale, wild, minor harvest fishery that enables the collection of brood stock for the pearl aquaculture industry. The general demand for wild-harvested pearl oysters in the Queensland sector is very low as the majority of shells produced for cultivation are derived from pearl oyster hatcheries [Department of Employment, Economic Development and Innovation 2009]. 

Catches have been low in recent years, rarely exceeding 500 shells per year and 50 days of effort. There has been a long history of low catches and effort of Silverlip pearl oysters and no collection occurred between 2012–13 and 2016–17. Annual catches between 2017–18 and 2021–22 have averaged 103 shells per year and 26 effort days, suggesting that the biomass of this stock is unlikely to be depleted and that recruitment is unlikely to be impaired. The harvest rate in 2021–22 was 158 shells and 31 effort days and is the highest catch rate in the last five years. Despite this, catch rates are still low in comparison to the historical peak of 419 shells and 32 effort days in 2008–09. It is reasonable to conclude that the current level of fishing mortality is unlikely to cause the stock to become recruitment impaired.

On the basis of the evidence provided above, Silverlip Pearl Oyster in Queensland is classified as a sustainable stock.

Silverlip Pearl Oyster biology [Hart and Joll 2006]

Distribution of reported commercial catch of Silverlip Pearl Oyster

Queensland – Indigenous (Management Methods) for more information see: https://www.daf.qld.gov.au/business-priorities/fisheries/traditional-fishing

Queensland – Commercial (Catch). Queensland commercial and charter data have been sourced from the commercial fisheries logbook program. Further information available through the Queensland Fisheries Summary Report https://www.daf.qld.gov.au/business-priorities/fisheries/monitoring-research/data/queensland-fisheries-summary-report

Commercial catch of Silverlip Pearl Oyster - note confidential catch not shown

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