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Topshell or topsnail Trochus niloticus
Illustration © R. Swainston www.anima.net.au |
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| Target species |
Topshells or topsnails Trochus niloticus
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| Status & trend |
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The trochus fishery began in the 1900s and flourished until the mid 1950s when plastics were introduced and plunged the industry into a depression. Renewed demand for natural buttons then stimulated a recovery of the industry. A declining demand and an unfavourable exchange rate (compared with $US) is driving a decline in the market.
Catch rates fluctuate annually, reflecting changes in demand.
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| Effort in GBRWHA in 2003 |
60 tonnes (Young and Challen 2004)
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| Gross Value of Production (GVP) in GBRWHA in 2003 |
$0.7m (DPI&F website)
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| Location of fishing |
Most fishing for Trochus is in tidal waters between Cape York and Gladstone . Mackay is the main port for the fishery.
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| Harvest methods |
Trochus is harvested by hand using non-mechanical implements either in the intertidal or when free diving. SCUBA or hookah area also permitted. Recreational fishers cannot use breathing apparatus.
The shell is tumble cleaned onboard then boiled. The meat is extracted and frozen, while the shell is bagged.
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| Management |
The trochus harvest fishery is managed by the Department of Primary Industries and Fisheries. A Total Allowable Catch of 300 tonnes is permitted for commercial operators who must be licensed and hold an ‘Authority to Take Fish for Trade or Commerce'. There are 6 authority holders. A minimum (8cm wide) and maximum (12.5cm wide) size limit for trochus applies to both recreational and commercial fishers (except to Indigenous fishers collecting for traditional or customary purposes). For recreational fishers, there is also a bag limit per person in possession. Collecting is restricted in some zones of the Great Barrier Reef Marine Park.
License holders complete compulsory daily logbooks which record fishing days and diver hours. Indigenous hunters are not limited in their catch or methods.
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| Further reading |
Young B, Challen S. 2004. Ecological assessment of Queensland ’s East Coast Trochus Fishery. A report to the Australian Government Department of Environment and Heritage from the Queensland Government Department of Primary Industries and Fisheries.
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