Biology:Pāua

Short description: Māori name for several species of sea snail

Ventral view of the shell of Haliotis iris.

Pāua is the Māori name given to three New Zealand species of large edible sea snails, marine gastropod molluscs which belong to the family Haliotidae (in which there is only one genus, Haliotis).

It is known in the United States and Australia as abalone, and in the United Kingdom as ormer shells. In New Zealand, these are known as pāua, which (as is common with all Māori words) is both singular and plural.

Species

There are three species of New Zealand pāua:

Species	Scientific name	Māori and common names
Pāua	Haliotis iris	Blackfoot pāua
Queen pāua	Haliotis australis	Silver pāua, yellowfoot pāua, hihiwa, karariwha
Virgin pāua	Haliotis virginea	Whitefoot pāua, marapeka, koio

New Zealand's best known pāua species is Haliotis iris. It is also the most common species, growing up to 18 cm (7") in width.

Habitat

Pāua are commonly found in shallow coastal waters along rocky shorelines in depths of 1 to 10 metres (3' to 30'). There is clear distinction between juvenile and adult habitats for Haliotis iris, pāua less than 7 cm (3") occur in crevices and under stones in the shallow intertidal zone while adults are found in subtidal zone.

Life

These large sea snails survive the strong tidal surges by clinging to rocks using their large muscular foot. They consume seaweed.

Harvesting

Pāua are gathered recreationally and commercially but strict catch limits are set for both. For recreational fishermen this is five pāua per person per day. The minimum legal size for caught pāua is 125 mm (5") for Haliotis iris and 80 mm (​3 ¹⁄₄") for Haliotis australis, measured in a straight line at the greatest length of the shell. The exception is Haliotis iris taken from the Amateur Taranaki Paua Fishery Area, which is the area of Taranaki coast bounded by the Awakino River in the north and the Whanganui River in the south, in which the minimum legal size is 85 mm (​3 ¹⁄₄"). However, pāua caught in this area cannot be taken east of State Highway 4 unless they meet the 125 mm (5") limit.

In addition, no single person may have in their possession at any time (including on land) more than 20 pāua or more than 2.5 kg (​5 ¹⁄₂ lb) of shucked (shell removed) pāua. Pāua can only be caught by free diving; it is illegal to dive for pāua using scuba equipment. All pāua must remain un-shucked until they are on the land side of the high tide mark so Ministry for Primary Industries (MPI) fishery officers can inspect them if required.

There is an extensive global black market in the collection and export of abalone meat. Pāua poaching is a major industry in New Zealand with many thousands being taken illegally, often undersized. The right to harvest pāua can be granted legally under Māori customary rights, but since permits to harvest are abused, it is difficult to police. The limit is strictly enforced by roving MPI fishery officers with the backing of police. Fishery officers can issue infringement notices of between $250 and $500 for minor offences, such as having one or two more pāua than permitted. More serious offences have resulted in hefty court convictions, including seizure of diving gear, boats, and motor vehicles as well as large fines and in rare cases, imprisonment. The Ministry of Fisheries expects in the year 2004/05, nearly 1,000 tons of pāua will be poached, with 75% of that being undersized.

Human use

A pāua shell bracelet

To Māori, pāua are recognised taonga, or treasure, esteemed both as kaimoana (seafood) and as a valued resource for traditional and contemporary arts and crafts. Pāua were often harvested by diving. Two traditional methods for collecting pāua included using a specialised flat tool called a māripi to pry pāua off the sea floor, or by placing an Astrostole scabra (seven-armed starfish), a major predator of pāua, atop the shell. Pāua could be eaten raw, smoked, cooked in a hāngī, or preserved. Preserved pāua were often kept for winter months, or used as items to trade with inland iwi.

Pāua shells are frequently used to represent eyes of human and animal figures in Māori carvings, and used as decorations on skirts, cloaks and in earrings. Pāua is traditionally are associated with the stars or whetū, the symbolic eyes of ancestors that gaze down from the night sky.

During the colonial era of New Zealand, British settlers detested the taste of pāua, but had an appreciation for the shells. Pāua shells were highly requested items on Second voyage of James Cook, and were highly sought after by 19th Century British jewellers. Eventually pāua became a part of the European New Zealander diet, first often appearing in soups and chowders. An international market for pāua meat began in the 1970s, after which pāua numbers dropped in the wild.

Whole shells were commonly used as ashtrays through the 20th century, and highly polished New Zealand pāua shells are popular as pieces of modern jewellery, with their striking blue, green, and purple iridescence.

Other names

Haliotis means 'sea ear' and some parts of the world use this term for various species. Pāua is also called "Sea Opal" in the United States and Australia .

Aquaculture

Background

Pāua aquaculture is a growing industry in New Zealand. The industry was started in New Zealand in the 1980s and to date there are 14 pāua farms operating which are located throughout New Zealand, from Whangārei to Stewart Island. The first farms that were started consisted of small scale back yard and shed farms in which techniques and processes that grew good quality pāua were developed and these are now being used on a commercial scale in the large pāua farms. These farms produce pāua for their meat, shells and some farms solely focus on the production of blue pearls. Most of the production from these farms is exported to the US, and Asian markets.

There is high demand on the worldwide market as decline in wild stocks due to over-fishing and poaching means that the global market for abalone is greatly under supplied.

Meat and shells

Most pāua farms on-grow pāua that is produced from wild broodstock, however some farms have developed their own hatcheries and selective breeding programs to produce faster growing species, the pāua are then grown to market size (depending on conditions this usually takes 2 – 3 years) in either long trays with inflow of seawater at one end and out flow at the other, or smaller tanks with tipper buckets that regularly dump seawater into the tanks to recreate wave motion that the pāua experience in the wild.

There are a number of different feeds used throughout the pāua's life-cycle. Pāua hatch as trochophore larvae and feed on plankton that are present in seawater that is being pumped into the holding tanks, when the larvae are ready to settle (usually 7 days at 16 °C; 61°F) they are moved to settlement tanks which consist of many glass plates that have small films of diatoms present (usually Navicula minimata). The diatoms are the main food source for the juveniles until they reach about 3 cm (1") in length then the diet is switched to a macroalgae species. Several species have been used, including Lessonia variegata, Pterocladia sp. and Ulva lactuca; however, research has shown that pāua will eat most seaweed species. The pāua are considered adults around 6 cm (2") in size and are then fed on a meal based diet until they are ready for processing and sale.

Pearls

New Zealand abalone pearls

To produce pāua pearls the pāua are harvested from the wild stocks (at the legal size of 12.5 cm; 5"), shell or plastic based implants are either poked through the shell or fixed in place under the shell with glue, the shape of the insert dictates the shape of the final pearl. After the pāua are “nucleated” they are kept in tanks for 2 to 3 years and fed on either seaweed or meal during which time they coat the insert with nacre . After the 2 – 3 years they are harvested from the tanks, the meat is shucked, and the pearl is then removed. The quality and size of the pearl changes depending on the size of the pāua. The pearls tend to be smaller when hatchery-reared pāua are used, which is why pāua from the wild are preferred. High stress levels within the farm can prevent the pāua from coating the insert to produce the pearl so control of the conditions in the farm to ensure that the pāua are not stressed is paramount in pearl production.

Popular culture

Pāua shells make up the decoration on Xena's first chakram in the hit TV series Xena: Warrior Princess. Although the show was set predominately in ancient Greece, the shell is used because the pāua is native to New Zealand, where the show was filmed.

References

• Powell A W B, New Zealand Mollusca, William Collins Publishers Ltd, Auckland, New Zealand 1979 ISBN:0-00-216906-1
• Kirk O. Hahn, Handbook of culture of abalone and other marine gastropods, CRC Press Inc, Boca Raton, Florida 1989 ISBN:0-8493-3528-0
• NZ Business (2010-04-10), "Growing paua plus", Dominion Post, http://findarticles.com/p/articles/mi_qa5373/is_200009/ai_n21460517/?tag=content;col1 
• National Institute of Water and Atmospheric Research (2006), Creating right conditions for paua, http://www.niwa.co.nz/news-and-publications/publications/all/wa/14-3/paua 
• National Institute of Water and Atmospheric Research (2008), Getting picky with paua: selective breeding to improve productivity, http://www.niwa.co.nz/news-and-publications/publications/all/wa/16-1/paua 
• Paua Industry council (2010), Facts about paua, http://www.paua.org.nz/paua.htm 
• NZ Business (2000), "Paua to the people", NZ Business, http://findarticles.com/p/articles/mi_qa5373/is_200009/ai_n21460517/?tag=content;col1 
• New Zealand Press Association (2006-05-30), "Paua industry wants stiffer penalties for thieves", The New Zealand Herald, http://www.nzherald.co.nz/index.cfm?objectid=10384228 
• Ministry of Fisheries (2007), Species Focus – Paua (purple paua – Halitosis iris), http://www.fish.govt.nz/en-nz/Publications/State+of+our+fisheries/Managing+Our+Catch/Paua.htm 
• Unlimited (2004), Paua pearl pioneers, http://unlimited.co.nz/unlimited.nsf/growth/paua-pearl-pioneersntent;col1 

Further reading

• McCrea, Malcolm (2005) Paua Craft: A Nga Paua.| url = http://www.pauamana.com Raupo Publishing (NZ). ISBN:0-7900-0995-1.