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Fisheries > New Zealand – Storm clam, Diamond shell, Deepwater tuatua, Ringed dosina – Hydraulic dredge - FAO 81

New Zealand – Storm clam, Diamond shell, Deepwater tuatua, Ringed dosina – Hydraulic dredge - FAO 81

Species: Mactra murchisoni, Spisula aequilatera, Paphies donacinia, Dosinia anus
Gear type: Hydraulic dredge
Fishing Area: FAO Area 81 Pacific Southwest

Fishery management:
The Ministry of Primary Industry (MPI) manages New Zealand’s fisheries by applying a variety of management measures to ensure that fishing is sustainable. The cornerstone of New Zealand’s fisheries management regime is the quota management system (QMS), which was introduced in 1986 and sets a yearly catch limit (or total allowable catch - TAC) for every fish stock. New Zealand law requires TAC limits for every fish stock to be set at levels that will ensure their long-term sustainability. The QMS manages 100 species in 638 stock areas. Other management controls imposed are closed areas, closed seasons, size limits, gear restrictions and prohibited species.

The QMS has delivered significant benefits – most of the stocks that were overfished before the introduction of the QMS now have sustainable catch limits in place. New Zealand is one of the few countries in the world that has an internationally competitive fishing industry that makes use of a natural resource on a sustainable basis.

Each year there is considerable investment in research and fisheries assessment, a significant portion of which is supported by the commercial fishing industry (2% of annual revenue). All research and assessment is reviewed by expert scientists, with participation by fisheries managers and representatives of environmental and commercial fishing interests.

The MPI invests heavily in monitoring fishing activity and in encouraging and enforcing compliance with the law. Fishery Officers patrol New Zealand’s coastline to ensure all fishers comply with the rules. In addition, Ministry Observers are periodically placed on fishing boats to monitor and record what fishers catch, and any interactions with seabirds, marine mammals or protected corals.

Stock status: The MPI carries out regular stock assessments in collaboration with the Industry members and Universities. The latest stock assessment was published by MPI in February 2016 and it is based on data from 2015. The biomasses of all clam species fished in Cloudy Bay are well above the lower limit of the maximum constant yield.

Habitat impact: The fleet uses hydraulic dredges and their effects on the seabed are continually monitored. A survey conducted in collaboration with the University concluded that the plume resulting from dredging completely disappears after less than thirty minutes. All the dredging activities are carried out on sand and mud seabed with no impact on kelp meadows nor nursery areas.

Discards: The hydraulic dredge allows selecting clams over a certain size so that the discards are low. Bycatch occasionally include sole, plaice and crab but these are either landed as catch or released live at sea.

Approved fishing vessels

Fishing vessel

Registration number

Vessel’s flag

Gear Type


Ship owner




Hydraulic dredge

Cloudy Bay





Hydraulic dredge

Cloudy Bay





Hydraulic dredge

Cloudy Bay




White, W.L., Millar, R. B., Farrington, G., Breen, D. and Selvaraj, S. (2015). Stock assessment of surf clams from Cloudy Bay, NZ. AUT Institute for Applied Ecology New Zealand Report 15/01



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