Aquaculture started to take off in New Zealand in the 1980s. It is dominated by mussels, oysters and salmon.FAO: National Aquaculture Sector Overview: New Zealand Food and Agriculture Organization of the United Nations, Rome. In 2007, aquaculture generated about NZ$360 million in sales on an area of 7,700 hectares. $240 million was earned in exports.New Zealand Ministry of Fisheries: NZ Fisheries at a Glance Retrieved 11 June 2008Aquaculture in New Zealand aquaculture.govt.nz
In 2006, the aquaculture industry in New Zealand developed a strategy aimed at achieving a sustainable annual billion NZ dollar business by 2025.Aquaculture in New Zealand MFish. Updated 3 November 2008. In 2007, the government reacted by offering more support to the growing industry.
Overview
Aquaculture is the general term given to the cultivation of any fresh or saltwater plant or animal. It takes place in New Zealand in coastal marine areas (mariculture) and in inland tanks or enclosures.
Aquaculture in New Zealand currently (2008) occupies 14,188 ha. Of that area, 7,713 ha is in established growing areas and is owned by the aquaculture industry, 4,010 ha is used to enhance the wild scallop fishery and belongs to the Challenger Scallop Enhancement Company,Tangal, Tracet (2006)The Challenger Scallop Enhancement Company: Collaborative Management of a Natural Resource Based in the Private Sector Public Administration Review. 66, pp. 148. and 2,465 ha is an exposed site six kilometres offshore from Napier where trials are being undertaken by a private company to test the site's economic viability.
In 2005 the aquaculture industry provided direct employment for about 2,500 full-time equivalents, mostly in the processing sector. A similar amount of indirect employment resulted from flow-on effects. The aquaculture industry is important for some coastal areas around New Zealand where there is limited employment. This applies particularly to some Māori communities with traditional links to coastal settlements.
Marine aquaculture, and mariculture, occurs in the sea, generally in sheltered bays along the coast. In New Zealand, about 70 percent of marine aquaculture occurs in the top of the South Island. In the North Island, the Firth of Thames is productive.
Cultured species There are three main species in the New Zealand aquaculture industry: the green-lipped mussel, the Pacific oyster and king salmon. In 2006 these three species generated $357 million in sales. Mussel accounted for 63 percent of this value, Pacific oysters 9 percent and king salmon 28 percent.
Value of farmed species in 2006 (NZ$ million) Common name Scientific name Domestic Export Total Green lipped mussel Perna canaliculus 43 181 224 Pacific oyster Crassostrea gigas 14 18 32 King salmon Oncorhynchus tshawytscha 59 42 101 Totals 116 241 357
Locality of farmed species, 2005 Species Farms(number) Area(ha) ProductionNZAC, 2006(tonnes) Locality Green lipped mussel 550Green Lipped Mussels Retrieved 3 March 2009. 4500 Particularly the top of the South Island, Pelorus Sound / Te Hoises, Tasman and Golden bays; but also the Hauraki Gulf and Coromandel, with a small number around Banks Peninsula and Stewart Island. Pacific oyster 236Marine Aquaculture MFish. Updated 16 November 2007. 928 North coast of the North Island: Coromandel, Bay of Islands and the Whangaroa, Mahurangi and Kaipara Harbours. King salmon 29 128 7,400 Mostly Marlborough Sounds and around Stewart Island, but also in channels below hydroelectric dams in the Mackenzie Basin.
Over two-thirds of New Zealand's aquaculture product comes from mussels and oysters. These shellfish are cultivated in two distinct stages; first spat needs to be collected, then the spat is grown in a grow-out facility.
Spat, also called seed, is the free-swimming larval stage of a shellfish. Spat is cultured in hatcheries, and can be grown in tanks on land. Hatcheries can also be associated with research facilities where spat can be selectively bred to specifications, as broodstock. A grow-out facility is the place where the spat are raised to market size, usually in enclosures anchored in coastal waters.
Mussels
Until the early 1960s, mussels were harvested by hand from intertidal rocks. Dredging was then introduced, and within a few years the mussel beds in Tasman Bay / Te Tai-o-Aorere and the Hauraki Gulf were dredged clean.Wassilieff, Maggy "Aquaculture: Green-lipped mussels" Te Ara – the Encyclopedia of New Zealand, updated 21 September 2007 In the late 1960s, following this collapse, the aquaculture of the New Zealand mussel began. The endemic green lipped mussel was used to trial growing mussel spat (young mussels) on ropes suspended from rafts. The Hauraki Gulf and the Marlborough Sounds provided sheltered environments, with clean water rich in plankton. The cultured mussels were ready for harvest after 12 to 18 months, and first went on sale in 1971.
More growers entered the industry. The labour-intensive raft method was replaced with a modified Japanese longline system. Biodegradable stockings were packed with spat and tied to parallel rows of looped ropes, supported by buoys. Young mussels grow through the stockings, anchoring themselves to the ropes with their strong byssal threads (beards). The farms are usually located in sheltered or semi-sheltered areas where there is sufficient depth of water at low tide to keep the longline droppers off the bottom. Recent research has been investigating offshore mussel farming in exposed areas several kilometres from shore, such as farms offshore from Napier and Ōpōtiki.
Initially the ropes were allowed to reseed naturally, after harvest, from the spat already present in coastal waters. However, this method was unreliable. In 1974 a marine scientist discovered mussel spat encrusted on drift kelp on Ninety Mile Beach. Locals collected the seaweed and air freighted it to mussel farmers. Kaitaia spat, as it became known, is now the prime source of seed mussels. There are some experimental hatcheries.
Improved techniques have led to rapid production increases, and bulk handling methods have been introduced to meet growing demand for export to more than 60 countries. By 2006 there were over 900 mussel farms in New Zealand covering about 6500 hectares, and worth about $224 million in annual sales. About $180 million were exports, usually sold as frozen mussels in half shells, patented with the trade name NZ Greenshell Mussels.
Oysters There are two types of wild oysters in New Zealand, Bluff oysters and rock oysters. Both have been commercially harvested since the mid-19th century. Bluff oysters have never been cultivated, but various attempts were made to cultivate the rock oyster.
Rock oysters are found naturally in the intertidal zone in the north of the North Island, and were subject to early cultivation experiments. During the 1960s, commercial farmers grew rock oysters on sticks coated with cement, and laid in racks in the lower intertidal regions of harbours and inlets around the northern North Island.Wassilieff, Maggy Aquaculture: Oysters and scallops Te Ara – the Encyclopedia of New Zealand, updated 21 September 2007
Then in 1970 another oyster started outgrowing the native rock oyster. This newcomer was the Pacific oyster, which had probably been introduced into New Zealand waters in the 1950s from a Japanese vessel hull or in their ballast water. At first, farmers tried to remove it from their collecting sticks, but year by year Pacific oyster spat increased, out-competing the native rock oyster.
Eventually commercial growers began to cultivate the Pacific oyster, and by the mid-1970s, it had become the main farm-raised oyster. Pacific oysters have well-established international markets, grow three times faster than native rock oysters, reach a larger size, have several spawnings each year and produce more consistent quantities of spat.NIWA: Aquaculture species: Pacific Oysters National Centre for Fisheries & Aquaculture. Retrieved 28 February 2009
In 1977 Pacific oysters appeared in the Marlborough Sounds, and farming began there in the 1990s. Instead of using the North Island method of cultivating oysters on racks, Marlborough farmers used hanging longlines, a system developed in Australia.
By 2006 there were over 230 oyster farms in New Zealand using over 900 hectares, and worth about $32 million in annual sales. About $18 million were exports.
Hatchery reared seed is not suitable for the rack systems which are still used by much of the industry. Pacific oysters on these racks are cultured from wild spat, most of which is gathered in the Kaipara Harbour. However, other systems are increasingly being used, including hanging longlines and plastic trays. The Cawthron Institute is the main provider of hatchery spat, and can selectively breed spat to specifications.Spat sales – Cawthron Institute. Retrieved 27 February 2009.
Salmon
Around 1900, different salmon were introduced as sport fish. Only the king salmon (Chinook) adapted to the environment.Farmed Species aquaculture.govt.nz. Retrieved 2 February 2009 For decades, the development of salmon and trout aquaculture in New Zealand was opposed by recreational fishers, on the grounds that disease would spread from fish farms into recreational fisheries, and that wild fish would be poached if they could be sold. In 1973 the government compromised by making trout farms illegal, but salmon farms legal.Wassilieff, Maggy "Aquaculture: Salmon" Te Ara – the Encyclopedia of New Zealand, updated 21 September 2007 New Zealand is probably the only country in the world where trout farming is illegal, despite commercial interest from companies already farming salmon.
In 1976, the first salmon farm was established at Pupu Springs near Tākaka. Salmon were raised in fresh water, growing to 25 centimetres over two years. The venture was originally aimed at ocean ranching, where juvenile salmon would be released into the sea with the expectation that some would return as adults. But few did return, so the Pupu Springs facility was converted to a hatchery, supplying stock to sea farms.
In 1983, the first sea-cage salmon farm was established in Big Glory Bay, Stewart Island. It was followed by farms in the Marlborough Sounds and at Akaroa Harbour on Banks Peninsula. These areas accounted for over 90 percent of the 8,500 tonnes of salmon produced in 2001.
Today, New Zealand accounts for over half of the world production of king salmon (7,400 tonnes in 2005).
Farming in the sea (mariculture) for king salmon is sometimes called sea-cage ranching. Sea-cage ranching takes place in large floating net cages, about 25 metres across and 15 metres deep, moored to the sea floor in clean, fast-flowing coastal waters. Smolt (young fish) from freshwater hatcheries are transferred to cages containing several thousand salmon, and remain there for the rest of their life. They are fed fishmeal pellets high in protein and oil. Most of this fishmeal is imported from Australia. The salmon are harvested when they are about two years old, weighing 2.5 to 4 kilograms. Sea cages are located in the Marlborough Sounds, Akaroa Harbour and Stewart Island.NIWA: Aquaculture species: Chinook salmon National Centre for Fisheries & Aquaculture. Retrieved 28 February 2009
Farming in freshwater for king salmon uses net cages placed in rivers, using techniques similar to those used for sea-farmed salmon. Freshwater raceways are located in several Canterbury rivers such as the Clutha and Waimakariri Rivers. In the 1990s, a unique form of freshwater salmon farming was developed in hydroelectric canals in the Mackenzie Basin. Young salmon are enclosed in pens in the Ōhau and Tekapo canals. The Tekapo site, fed by fast cold waters from the Southern Alps, is the highest salmon farm in the world, 677 metres above sea level.