Seafood is healthy and the world wants more. Too bad that most wild fisheries are overfished and collapsing. Over the last few dec­ades, aquaculture has begun to offer a solution to this difficulty, but it’s not a solution that wins universal acclaim. In New Zealand, the black floats that mark mussel farms (above)—our main form of aqua­culture—are often considered an eyesore and an impediment to our unfettered access to sea and shore. But while locals are apprehensive, government and the industry have an eye to expansion.

Written by       Photographed by Darryl Torckler

I’m in my element and perfectly positioned in a quiet corner of Beatrix Bay to capitalise on a fisher’s favourite time—change of light. The autumn air carries a hint of cold, but shivers are shrugged off as the first rays of morn­ing sun bounce off a nearby ridge, re­vealing a labyrinth of waterways that are home to big snapper and a delicacy of another sort—mussels.

It’s an idyllic morning in the Marl­borough Sounds. Across the bay the purpose-built tunnel-hull Innovator straddles a mussel line, swallowing a row of floats as it inches forward. The muted throb of the vessel’s diesel en­gines reaches my ears just as my rod tip dips. Snapper!

I’m surrounded by rows of black floats that indicate this is a major ma­rine-farming area, and it seems incon­gruous to be chasing wild creatures here. But the Marlborough Sounds is a canvas of broad contrasts. Innova­tor may be harvesting mussels, but in no sense does this enterprise bear any resemblance to the livestock farms that occupy nearby hills. In fact, this quiet mussel farm is much more productive than a terrestrial farm. In the Sounds, the hub of New Zealand aquaculture, 2153 ha of marine farms produce 50,000 tonnes live weight of green-lipped mussels a year, whereas 500,000+ ha of land are required to raise the equivalent weight of sheep meat. Indeed, mussels are now New Zealand’s second-largest seafood ex­port as well as the backbone of the country’s marine-farming enterprise. Aquaculture has been in New Zealand for only 40 years, but it has grown rap­idly—some would say too rapidly—and looks set to keep on expanding.

Oysters were the fi rst species to be cultivated locally, and they remain the main form of aquaculture in northern New Zealand with quiet harbours, such as the Mahurangi seen here, the focus of activity. Paua are being grown for both meat and pearls, but so far there are not more than a score of farms.
Oysters were the fi rst species to be cultivated
locally, and they remain the main
form of aquaculture in northern New
Zealand with quiet harbours, such as the
Mahurangi seen here, the focus of activity.
Paua are being grown for both meat
and pearls, but so far there are not more
than a score of farms.

Despite their present importance, mussels were not the first marine spe­cies to be farmed commercially. That honour goes to the northern rock oys­ter, once harvested in huge quantities in the wild. The impetus for the birth of New Zealand’s aquaculture indus­try was the depletion of natural stocks of that oyster. In the early 1950s, the Marine Department conducted ex­periments to determine the viability of growing oysters commercially. By 1957, rock oysters were being grown to a marketable size in three-and-a-half years, compared with the seven years it took them in the wild.

A trial farm was established in Orongo Bay in the Bay of Islands, and the initial harvest in 1967 netted 431 bags, which sold in Auckland for $4098—far ahead of what feral oysters were fetching. Aquaculture had ar­rived, and it flourished as demand for farmed oysters—plumper and sweeter than their wild counterparts—grew. The 1970s saw the arrival of the Pacific oyster, allegedly ferried to New Zea­land on the hulls of Japanese freight­ers. This species was not as tasty as the northern rock oyster, but it was faster growing and soon replaced the rock oyster to become the farmers’ bivalve of choice.

Around this time the green-lipped mussel was suffering from over-har­vesting, and the county’s largest natu­ral beds, on the floor of the Hauraki Gulf, were on the brink of collapse. Dredge fishing peaked in 1965, when 41,000 sacks (2000 t) of mussels were landed in Auckland. Only two years later the harvest was less than 400 sacks.


As natural stocks in the gulf and Kaipara Harbour dwindled, poaching became rife, particularly around the Coromandel Peninsula. A huge pub trade in raffled mussels blossomed. The profits to be made from poaching were enormous—providing one could elude an increasingly vigilant Ministry of Agriculture and Fisheries. Divers worked the beds by night, and planes were even called in to fly sack loads of mussels off beaches to avoid road­blocks. Death threats to MAF officers were common and fisticuffs frequent.

For a time, Auckland’s demand for mussels was largely satisfied by dredged mussels from Tasman Bay. These were initially a by-catch of the trawler harvesting of scallops, but such was demand that stocks were quickly depleted. As with the rock oyster, the decline in natural stocks led to attempts at farming, with the first experimental raft, based on a Span­ish design, set up in the Marlborough Sounds in 1967. Lines with larval mus­sels, or spat, attached were suspended underneath a square pontoon raft, and the mussels flourished. In 1971 an old front-loader tractor was driven onto a barge and used to lift the lines in the first commercial harvest of mussels in New Zealand. Over 7 tonnes were taken from just a few lines, and mussel farming became a reality.

After the passage of the Marine Farming Act in 1971, the industry expanded rapidly, with concomitant improvements in farming practice and processing. Over the next 20 years mussels became a commonly avail­able gourmet food. Life wasn’t easy for many mussel farmers, who struggled to feed their families and keep their farms afloat, but the challenging times built a foundation of doggedness, re­silience and determination that per­sists to this day.

[Chapter Break]

Innovation has always been a catchcry of the aquaculture industry,

and in the mid-1970s the Japanese long-line system replaced the use of rafts in mussel farming. Two stout support ropes are strung either side of a row of large floats and anchored to the seafloor at each end. A continuous line is suspended from the backbone of floats to the desired depth in a series of loops, called droppers. Spat is attached to these in stockings that eventually rot away, leaving the mussels to grow unhindered.

Most mussel farming takes place in the Marlborough Sounds, around the Coromandel Peninsula and in Stewart Island’s Big Glory Bay, while approval has recently been given for the devel­opment of a marine farm in Jackson Bay, south Westland. There is also interest in establishing large offshore mussel farms, perhaps on submerged support structures. A 10,600 ha farm of this type off the Canterbury coast has been proposed.

The green-lipped mussel, Perna canaliculus, is reared from tiny spat (left) to a 100–120 mm adult in 12–18 months. High pressure water jets are used to clean encrusting organisms from freshly-harvested mussels.
The green-lipped mussel, Perna canaliculus, is reared from tiny spat to a 100–120 mm
adult in 12–18 months. 

The New Zealand aquaculture in­dustry today is worth $320 million annually, with domestic consumption accounting for around 40 per cent of sales. It is an expanding industry, not only in both production and profit­ability, but also in the diversity of spe­cies farmed. The flagship species are the greenshell mussels, followed by king salmon and Pacific oysters. Aba­lone (paua), kingfish and freshwater crayfish are in the early stages of com­mercial farming.

King salmon were introduced in the 1800s with the intention of establish­ing a commercial fishery, but numbers never reached the point where a wild fishery was commercially viable. How­ever, late last century king-salmon farms were established in the Marlbor­ough Sounds, on the east coast of the South Island and on Stewart Island.

Salmon are peculiar in that they live in the sea as adults yet swim up­river to spawn in freshwater. Con­sequently, farmed king salmon are reared from eggs in freshwater hatcheries, then generally grown to adult­hood in saltwater pens, either in river mouths or in sheltered bays. After 10– 20 months they reach harvest weights of 3–3.5 kg.

Abalone are shellfish that graze on seaweed and are considered a delicacy in many parts of the world. While they are found across the globe, the black-foot paua, with its spectacular blue-green iridescent shell, is restricted to New Zealand waters. Aquaculture ventures have been set up around the country to farm paua, not only for their meat, but also for pearls (see New Zealand Geographic, Issue 39). Other potential subjects for aquaculture in­clude eels, whitebait, rock lobsters, snapper, sea cucumbers, kina, Bluff oysters, geoduck clams (pronounced gooey-duck) and turbot, as well as some seaweeds and sponges.

Aquacultural enterprises benefit rural New Zealand, bringing invest­ment to coastal regions and creating jobs in areas that have suffered from centralisation. Aquaculture currently provides 2500 full-time job equivalents in Northland, Waikato, Marlborough, Nelson, Canterbury and Southland, with flow-on effects creating a further 4000 jobs. Every job directly created by aquacultural operations generates 7–10 jobs in processing and 0.4 jobs in the wider community. New Zealand aquaculture now employs nearly 30 per cent of the total seafood-industry workforce.

The small rural town of Have­lock, at the head of Mahau Sound, is one community that has been trans­formed by mussel farming. According to Graeme Barsanti, local policeman and Marlborough district councillor for the past 15 years, two-thirds of the town’s population work in the mussel industry. Others are employed in tour­ism and the food and beverage indus­try, both of which have flourished on the back of mussel farming since the early 1990s.

“With good jobs, people have spent money doing up their properties and renovating the local shops and setting up new businesses,” Barsanti says. “A lot more families have arrived. The school roll is up and we have a per­manent doctor. There are four engi­neering firms, a bakery, a dairy, a Four Square store, a tearooms, the Mussel Boys restaurant and the Clansman Tavern. As you drive into town now it looks good.”

The small Northland town of Kaeo is another example of how aquacul­ture has given new life to a commu­nity. Before seafood company Sanford converted an old dairy factory into an oyster-processing plant in 1999, the town was developing an air of neglect;unemployment was high and govern­ment benefits provided a major source of local income. The plant employs over 100 staff on a seasonal basis and is the town’s main employer.

[Chapter Break]

Aquaculture could have done even better, however. Growth has been hobbled by regulations and bureaucracy. In 2000, industry leaders set a goal of exports worth $1 billion—three times current produc­tion—by 2020, but that was soon put back to 2025.

High pressure water jets are used to clean encrusting organisms from freshly-harvested mussels.
High pressure water jets are used to clean encrusting organisms from
freshly-harvested mussels.

With the accelerated growth of marine farming in the late 1990s, the demand for water space increased five­fold, and by 2000 it had become appar­ent that the legislation for planning and approving marine farms couldn’t cope with demand. Marine farmers, desper­ate for more space, were unhappy over delays and costs in the processing of their applications, while communities were growing anxious that the possible environmental effects of marine farm­ing were not being fully recognised and managed.

In response, the government im­posed a moratorium on permit appli­cations from November 2001 to the end of 2004 while it prepared new leg­islation to ensure further development was sustainable and environmentally appropriate. The process culminated in the Aquaculture Reform Act 2005 and the Maori Aquaculture Claims Settlement Act 2004. During the three years of the moratorium, sales from the existing 900 farms grew by only 30 per cent, compared with 230 per cent over the previous decade, when new farms were being established.

This wasn’t in fact the first such moratorium. Marlborough District Council and the Department of Con­servation (DOC), concerned over the number of applications for marine farms in the Marlborough Sounds, had imposed one locally in 1996 while they considered controlling applica­tions through the Conservation Act 1987. This proved impossible, how­ever, so the moratorium was lifted in 1999.

Then came a flood of mid-bay ap­plications aimed at testing the Marl­borough Sounds Resource Manage­ment Plan, which allowed only ribbon development of the coastline out to 150 m from the shore. However, law­yers for the applicants spotted a poten­tial loophole and made application for a number of large farms each cover­ing some 50 ha. The plan ultimately proved robust and none of the applica­tions was successful.

Steffan Browning, a spokesper­son for the environmental watchdog Friends of Nelson Haven Inc., which, together with DOC, opposed the ap­plications for mid-bay farms, said the process was long, arduous and costly, both in dollar terms and in the toll it took on people. Browning is no stranger to legal battles, having suc­cessfully fought a lone crusade to halt the development of mussel farms in the outer Sounds near Forsythe Is­land. He isn’t opposed to marine farms per se, but believes that “We have a responsibility to protect the aesthetic values of a region and, quite simply, we need some stretches of natural coast­line left.” The judge obviously agreed, because Browning won and his case—Browning vs Marlborough District Council—is now used as case law.

Browning believes marine farming in the Sounds has reached saturation point and advocates a strong precau­tionary stance, at least until the eco­logical effects of the industry are bet­ter understood. He cites the applica­tion for a large mid-bay mussel farm in Admiralty Bay, near French Pass, as an example of the need to consider quite localised environmental factors with regard to aquaculture ventures.

Mussels are grown attached to ropes in clean open water with a good tidal flow. Supreme water quality is important, because the bivalves will filter out and accumulate any particulate contaminants, such as algae from toxic blooms or bacteria and viruses washed from nearby land.
Mussels are grown attached to ropes
in clean open water with a good tidal
flow. Supreme water quality is important,
because the bivalves will filter
out and accumulate any particulate
contaminants, such as algae from toxic
blooms or bacteria and viruses washed
from nearby land.
While the country’s 645 mussel farms produce 95,000 tonnes of shellfish from 4750 ha of coastal water, no other species looks close to that sort of expansion.

Admiralty Bay is a significant winter feeding ground for large numbers of dusky dolphins that come up the coast from Kaikoura. Scientists are intrigued by the behavioural changes the sea mammals exhibit when they frequent the region. During the rest of the year, they generally feed individu­ally and at night. In Admiralty Bay they change to collective daytime feed­ing, small pods herding pilchards into “meatballs” inside the bay. Browning says environmentalists were worried about the effect further aquaculture development might have on the pilchards and, in turn, on the dolphins.

“You have to take a holistic approach when considering environmental fac­tors,” he says, “and a change to part of the food chain could seriously affect the welfare of the dusky dolphins.”

Boaties also played a part in swaying the decision against the Admiralty Bay venture, arguing that it was a critical shelter in bad weather. There were al­ready 44 farms about the bay’s perim­eter, and the addition of a huge farm in the middle of the bay would present a hazard to navigation and curtail anchoring opportunities. Mussel-farm­ing business Kuku Mara Partnership unsuccessfully argued that the local industry needed 1000 tonnes of mussels a weak to keep the factories operating efficiently.It saw the proposed mid-bay farm as a back-up for coastal farms that were often closed for long periods during harvest because of run­off from high rainfall contaminating inshore waters.

The result of such environmental alarms and delays is that, while the aquaculture industry nationally has es­sentially stood still since the 2001 gov­ernment moratorium, in Marlborough there has been a decade of uncertainty, marked by sluggish growth.

[Chapter Break]

According to the United Nations Food and Agriculture Organisation, aquaculture is already pro­ducing a third of the world’s fish and shellfish supply, and forecasts suggest that by 2020 it will account for 50 per cent of global seafood production.

Minister of Fisheries Jim Anderton wants to see the value of New Zealand’s seafood resource at least double in the next 10 years without any more fish be­ing taken from the wild. The way to do this, he says, is to develop aquaculture and add value to the wild-fish catch. He cites the Chilean salmon industry: “In less than two decades they have built an industry from nothing to one that earns around three billion dollars a year, more than twice as much as our entire seafood industry.”

While New Zealand aquacultural­ists remain positive, this billion-dollar vision seems set on a collision course with reality, due in part to the growth of another industry spawned by the 2001 moratorium—bureaucracy. The Aquaculture Reform Act has sent more than a ripple through the industry be­cause it is not seen as being conducive to immediate growth.

One of the requirements of the Act is that regional councils designate areas where they deem marine farm­ing appropriate—so-called aquacul­ture management areas (AMA)—and manage these accordingly. An AMA can be proposed by a council itself or by a private individual or group; in ei­ther case, the initiator meets the costs involved. However, in the two years since the marine-farming indus­try was brought under the Resource Management Act 1991—the principal legislation setting out how the environment is to be managed—no new AMAs have been created.

Eels seen at NIWA’s aquaculture research facility in Bream Bay, have good market potential internationally but are still very difficult to culture.
seen at NIWA’s aquaculture research facility
in Bream Bay, have good market potential
internationally but are still very difficult
to culture.

Ministry of Fisheries (MFish) aqua-culture manager Dan Lees says it could take several years to establish any AMAs because there is a legal process to go through and the public needs to be notified. Others argue that councils are reluctant to spend ratepayers’ mon­ey investigating potential AMAs when every suggestion prompts an outcry from a vocal minority. There is also concern that research into new aqua-culture species, methods and locations is being hampered by this impasse.

The government has recently an­nounced a $2.9 million package to as­sist councils create AMAs, but to date there is none in the pipeline.

Also to be taken into account is the Maori Aquaculture Claims Settlement Act, which allocates Maori a share of the marine-farming pie. The settle­ment promises iwi assets equivalent to 20 per cent of the water-space rights created in coastal waters since September 2, 1992, and rights to 20 per cent of any new space allocated to AMAs in the future. It does not apply to freshwater aquaculture, land-based marine farms, or any aquaculture ventures established outside the 12 nautical mile zone.

The act sets a limit of 10 years in which to settle claims, but there is concern as to where additional space is to come from. After January 2008, MFish will have the power to pur­chase space on a willing buyer–will­ing seller basis, but watchdog groups like Friends of Nelson Haven ques­tion whether the government will be able to fulfil its obligation and are concerned the pressure to find new space may see changes to the plan that impact on current prohibited areas.

The National Party, meanwhile, observes that if the ministry cannot find water space equivalent to around 240 marine farms (1943 ha) to gift to Maori by 2014, the Crown’s legal ob­ligation to make cash settlement will see taxpayers out of pocket by $250 million.

In spite of the obstacles, the New Zealand aquaculture industry is de­termined to move forward and, true to that doggedness of spirit developed in the early years, is implementing its own changes to help it advance. The various marine-farming groups are amalgamating in one body, the New Zealand Aquaculture Council (NZAC), so the industry can develop a unified strategy and speak with a single voice.

Hundreds of millions of dollars will need to be invested in aquaculture if the growth targets are to be met, yet the impasse in setting up AMAs and uncertainty hanging over the issue of renewing existing consents make in­vestors nervous. The industry believes getting tenure over water space is es­sential and that it should be a formality for a 20-year-old resource consent to be renewed provided the marine farm­er has operated satisfactorily.

Understandably, the NZAC is keen to assist councils identify areas suit­able for environmentally sustainable AMAs.

Fin fish, such as salmon and kingfish are much more valuable on a per kilo basis than mussels and oysters, but the pelletised feeds they require are also expensive and often based on ingredients from wild-caught fish
Fin fish, such as salmon and kingfish are much more valuable on a per kilo basis than
mussels and oysters, but the pelletised feeds they require are also expensive and often
based on ingredients from wild-caught fish

The Maori Aquaculture Claims Settlement Act has ensured that Maori have a significant role to play in the future development of aquac­ulture in New Zealand. Maori appear happy in principle with the new di­rection. John Mitchell, spokesperson for top-of-the-South Island iwi Ngati Tama, says local Maori are grateful that they have finally been listened to and that the present government has recognised there are treaty issues that need addressing.

“Now we at least have a policy in place that offers us a way forward,” he says.

Mitchell sees Maori involvement in aquaculture as a crucial step in providing local iwi with the ability to continue with and further develop current cultural and social initia­tives. Most tribes in the district op­erate as charitable trusts that make grants to groups and individuals for educational and cultural activities. No dividends are paid to individuals. Ngati Tama support marae by pur­chasing such items as fridges, stoves and sterilisers, and assist with the re­furbishment of buildings.

“We make grants to kapa haka groups to assist with the development of language and cultural skills, and provide ongoing support of groups attending national competitions,” Mitchell explains.

A spokesperson for iwi in the far north, James Murray, says aquacul­ture has the potential to bring sig­nificant benefits to iwi and it seems a logical progression that Maori be in­volved given their historical connec­tion with the sea.

“Our relationship with the sea is a spiritual matter. It has focused on the sea as a source of food—kai moana­ for survival. We are very concerned about the sustainability of natural fish stocks because we mustn’t de­prive our grandchildren of the op­portunity to gather seafood. That’s what it’s all about.”

Rawiri Morunga is a man who has been transformed by aquaculture. Brought up in Canterbury, Otago and Southland, he didn’t do well at school, leaving at age 14 to become a street kid and then a shearer. Later he worked in timber mills and freezing works. With this background, it seems unlikely he would ever find himself in the very profession that failed him as a child­ teaching.

Unfortunately, few fish feed directly on diatoms and other planktonic organisms, and those that do are not much favoured as food fish.
Unfortunately, few fish feed directly on diatoms
and other planktonic organisms, and those that do are not much favoured as food fish.

But the street kid has indeed turned tutor, Morunga now teaching a one-year aquaculture course for Bay of Plenty Polytechnic at Kaitaia. The Level Four National Certificate in Seafood is run in conjunction with the Northland Maori training organisa­tion Muriwhenua Wharewananga. Students range in age from 18 to 40+ and learn everything from seafood processing to aquaculture legislation. On completion of the course they can continue with further education, such as a Diploma in Fisheries Management,or enter the aquaculture industry.

“One of my former students is al­ready managing an oyster farm,” says Morunga.

Many of his students have plenty of life experience but, like him, never mastered the academic stuff at school. Most embrace the course as an oppor­tunity to make a difference to their whanau or hapu, both in protecting valuable marine resources and in cre­ating work opportunities. Morunga sees training as the key to the future of iwi in the far north.

“We need to up-skill as many people as we can with the Te Ohu Kai Moana resources about to be returned,” he says, referring to the transfer of ma­rine assets from the Treaty of Wait­angi Fisheries Commission to tribes.

However, while potential opportu­nities arising from the new aquacul­ture initiatives in New Zealand excite Maori, there is growing frustration over delays in implementation. Mitch­ell says that since the act came into force, not a single hectare of water space has been transferred to Maori.

“What we have is lofty sentiments. Maori are essentially happy with the policy, but the execution has been poor.”

And he doesn’t just blame central government. The lack of urgency among regional authorities has also contributed to the situation, as has ongoing litigation over water space round the top of the South Island, to which Maori are party.

Another frustration is that the new law hasn’t simplified the process of ap­plying to set up a marine farm. If any­thing, Mitchell thinks, matters have become worse. A would-be farmer now has to apply to the appropriate region­al authority for an AMA and then go through the resource-consent process to get the AMA ratified. But the final decision as to whether the AMA goes ahead rests with MFish, which has the power of veto if it believes the AMA could have a negative impact on fisher­ies. Mitchell sees MFish as being at the wrong end of the chain.

“They should be involved at the start of the process, and if they have concerns, stop the application in its tracks! Under the current system, ap­plicants are faced with the possibility of spending lots of money only to learn that the expenditure and effort have been in vain.”

[Chapter Break]

While enthusiasm for growth may be strong in the aquaculture sector, others are urging caution and some fret that projected growth cannot be managed sustain-ably. Browning says the call for greater innovation and added value could see the conversion of shellfish farms to higher-value salmon farms—to the detriment of the environment and wild fisheries.

Nelson’s Cawthron Institute is experimenting with culturing organisms in large ponds  which could be used for the large-scale growth of algae, perhaps in conjunction with a high-value filter feeder such as geoduck.
Nelson’s Cawthron Institute is experimenting with culturing organisms in large ponds
which could be used for the large-scale growth of algae, perhaps in conjunction with
a high-value filter feeder such as geoduck.

Mussel farms are largely extrac­tive, taking plankton from the water, whereas salmon farms, says Browning, carry the risk of pollution. The penned fish are reared on high-nutrient fish feed, a percentage of which drops to the seafloor. Browning says that the effects this may have on the marine ecosystem have not been sufficiently studied and calls for more independent research before there is any expansion of fin-fish farming.

Mark Gillard, operations manager of the New Zealand King Salmon Company, believes fin-fish farming has a great future in New Zealand and is sustainable. Success relies on good management of water quality, as salm­on are very susceptible to environmental deterioration. His company hires the Cawthron Institute to monitor the water quality of its farms and reports the results to Marlborough District Council. Some of the farms have been in operation for 17 years and so far the company has received no complaints from the council.

Browning, however, remains con­cerned that we have an inadequate understanding of the potential long­term impact of marine farming on the environment. It has long been held that filter feeders such as mussels are herbivorous, extracting only phyto­plankton from the water, but Brown­ing quotes international studies that show bivalves, including mussels and oysters, also remove some zooplank­ton from the food chain. Concern has been raised that widespread farming of mussels and oysters could so reduce zooplankton as to adversely affect populations of larger creatures that feed on it, including fish.

Browning says that fish eggs form part of this equation and questions whether mussel farming could be con­tributing to the decline of some fish stocks. In recent years the Marlbor­ough Sounds blue cod fishery has suf­fered near collapse, prompting MFish to reduce daily catch limits for recrea­tional fishers from six fish per person per day to three. When the daily bag limit was introduced in the mid-1980s, the limit was 36 fish per person and thought to be sustainable.

The National Institute of Water and Atmospheric Research (NIWA) acknowledges the international stud­ies and says that to date comparatively little has been done to study the effects of bivalve filter feeders in New Zea­land. A limited laboratory study has been carried out but was inconclusive.

For their part, many recreational fishers have now accepted aquaculture as an integral part of the seascape and use it to their advantage. Mussel farms attract a range of fish species to their structures, making it easier for fishers to find them. Snapper, kingfish, gurnard, John Dory, hapuku and blue cod are some of the popular species that form part of the complicated food chain as­sociated with mussel farms. Some move in to feed on the small crustaceans that shelter in farms, others prey on small fish that make their homes there, while yet others, such as snapper, make a meal of the mussels themselves, particularly during the spat stage.

The lines of floats provide fishers with a stable structure to tie up along­side. Harvesters, like Innovator, often provide a dual service, stripping the mussels from their lines on the one hand and attracting fish on the other. The sound of working machinery, magnified underwater, travels some distance, acting like a dinner gong for predatory species such as snapper and kingfish. The fish home in on the huge berley trail of discarded organ­isms and broken shells, a by-product of the harvesting operation. Canny fishers drift baits into this temporary muddy trail of waste, hoping for that telltale thump on the line that heralds the arrival of snapper.

Browning also thinks there is a lim­it to the number of mussels an area can sustain. He claims that in some parts of the Marlborough Sounds, farmers have found that mussels are slow to fatten, prompting many to thin out their lines to increase current flow. He notes that during the flood of mid-bay applications, many of the opponents were existing marine farmers.

“They were struggling to fatten their crops and were concerned addi­tional farms would only be competing for the same nutrients.”

He’s worried that the pressure to de­liver the Maori quota and the demand for more space could upset the balance of nature and have dire consequences for the industry and the marine en­vironment around marine farms. He sees an urgent need for more scientific study of the impacts of aquaculture on the environment and advises a softly-softly approach to expansion.

NIWA’s Barb Hayden, on the oth­er hand, urges people to stand back and look at the bigger picture, point­ing out that changes in the ecosystem are often the result of natural cycles or of external forces such as fishing. She explains that NIWA has conducted in­tensive studies of the levels of phyto­plankton in the Marlborough Sounds, and the ecological models it has devel­oped suggest the Sounds are not over­stocked with marine farms.


Hayden says there is now clear evi­dence that when farmers were strug­gling to fatten their mussels (from the late 1990s to the early 2000s), the problem was reduced nutrient flows into the Sounds from rivers and from up-welling in Cook Strait brought about by long-term climatic cycles. While she acknowledges mussels eat fish eggs, she doesn’t believe their lev­el of consumption is likely to have any significant impact on the ecosystem.

Ken Grange of NIWA in Nelson agrees: “Mussels can’t distinguish be­tween spotty eggs and blue-cod eggs, and there are a hell of a lot of spotties around mussel farms.”

Floor Anthoni, an independent marine biologist from Auckland, argues that the question mark over sustain-ability is very real and of global signifi­cance. He claims that New Zealand’s coastal seas, above the continental shelf, have been deteriorating rapidly for the past 20 years, choked by run­off in the form of soil, fertilisers and other pollutants.

He says that New Zealand loses around 270 million tonnes of soil to the sea every year, and that the rate of loss is greater than in any other country and accelerating. Most rivers in farm­ing areas fail to meet recommended guidelines concerning dissolved nu­trients, turbidity and animal faecal matter. Anthoni claims the country’s marine reserves aren’t working and that organisms are disappearing as a result of environmental degradation. He quotes a study of the jewel-in-the­crown Poor Knights Islands Marine Reserve, commissioned by DOC in 2003, which highlights a chronic de­cline of fish species and a deterioration of water quality.

Nelson’s Cawthron Institute is experimenting with culturing organisms in large ponds (opposite) which could be used for the large-scale growth of algae, perhaps in conjunction with a high-value filter feeder such as geoduck. Most algal culture is small scale. At NIWA, Bream Bay, seed cultures in flasks are expanded into large plastic bags (above) and the algae then fed to zooplankton on which infant fish are reared.
Nelson’s Cawthron Institute is experimenting with culturing organisms in large ponds (opposite)
which could be used for the large-scale growth of algae, perhaps in conjunction with
a high-value filter feeder such as geoduck. Most algal culture is small scale. At NIWA, Bream
Bay, seed cultures in flasks are expanded into large plastic bags (above) and the algae
then fed to zooplankton on which infant fish are reared.


If our marine reserves are failing,Anthoni says, it doesn’t take a stretch of the imagination to work out the state of the rest of the coastline. “In­deed, it looks like our seas are increas­ingly less suitable for marine life, and this includes all forms of fishery,” he goes on. “New Zealand has entered a new era marked by fish-recruitment failures and fisheries collapses, and aquaculture is not exempt from this.”

[Chapter Break]

While the industry clearly wants more space, there is a call for it to make more money from what it currently produces. Impressed by the Chilean-salmon model, Min­ister Anderton sees New Zealand as having the potential to mirror that success, and not just with salmon. But mussels and oysters won’t do it, at least not as they are marketed now. New Zealand averages a return of $3 per kilo for its aquaculture produce while Australia earns $20 per kilo. Much of the reason for the discrepancy is that shellfish are the staples of New Zea­land aquaculture, rather than higher-value fin fish such as salmon.

Anderton says that competing with bulk producers is a race to the bottom, with the global market setting the price and those selling becoming the price takers. On the other hand, “The global demand for high-value products in high-value markets is growing.”

New Zealand King Salmon is now exporting vacuum-packed smoked salmon morsels and ready-to-cook salmon kebabs, rather than whole frozen fish, and has developed a way of utilising virtually every part of a salmon. Last year it launched onto the local market a product that has curried immediate favour with recreational fishers—berley. This is a powerful fish attractant made from minced by-prod­uct and fish frames.

Science is also providing leads in the race to diversify, with exciting progress in fields such as seawater-pond aquaculture. The Cawthron Aquaculture Group has been experi­menting with seawater ponds at the Glenhaven Aquaculture Centre near Nelson for seven years and is confident the concept has huge potential for the industry.

The ponds produce large quantities of phytoplankton at low cost, which can be used as food for filter-feeding shell­fish. Experiments to date also indicate potential for commercial spat-grow­ing nurseries and shellfish-fattening farms, for the live-feed production of zooplankton for seahorse farms and small fin fish, and for the production of micro-algae for use in health-food sup­plements and pharmaceuticals. Such pond technology may also be suitable for high-value shellfish farming, with a leading contender being the geoduck clam. This delicacy enjoyed brief com­mercial acclaim in the late 1980s, but natural stocks were quickly over-fished. Other invertebrates, too, such as marine worms, could prove suited to this style of farming. For instance, rag worms and bristle worms are important in the production of extruded shrimp and fish feeds used in aquaculture.

NIWA is investigating the use of polyculture—growing, for example, mussels, paua, sea cucumbers and seaweed together. Sea cucumbers can devour all the waste products of paua (providing the latter are fed an algal diet) and are valued in Asia as food and for their medicinal properties.

NIWA operates a large aquacul­ture facility beside the old Marsden B power station in Bream Bay, south of Whangarei, sucking some 200 L of seawater a second through an old cooling-water inlet. Michael Bruce, NIWA’s national centre leader for aquaculture, explains that his team’s role is to carry out research to facili­tate the successful commercial imple­mentation of aquacultural projects.

“Aquaculture is at the practical, com­mercial end of the science spectrum. One of my jobs is to identify compa­nies interested in aquaculture and then help them with the research needed to establish an enterprise. If we can’t find a commercial partner for a project, it’s unlikely that we will pursue it.”

Species on which NIWA’s aquacul­ture team has worked in the last few years include kingfish, eels, paua, rock lobster, oysters, kina, salmon, snapper and turbot. Turbot—a large flatfish­ is considered too slow-growing to be useful, and there are no companies currently interested in snapper farm­ing—although it is easy—so these species are not of further immediate interest. Inside NIWA’s complex of large low sheds are mazes of pipes and tanks. Some of the largest tanks­ holding 75 tonnes of seawater—are home to large brood-stock kingfish. In smaller tanks, hundreds of thou­sands of 150 mm-long offspring cir­cle in the current created by incom­ing water, destined for on-growing in sea cages in the Sounds. In shallower dark tanks scores of eels writhe.

“There is a terrific market for these,” says Bruce, “but the complexi­ties of their life cycle mean that breed­ing them in captivity is, as with rock lobsters, proving to be a challenge.”

Single-celled algae—food for zo­oplankton—grow as golden soup in large sausage-like plastic bags up to 4 m long and 0.5 m in diameter. In a nearby warm-room, a French techni­cian oversees a seething tank of rotif­ers, animals the size of a full stop that devour algae and in turn are fodder for larger creatures. Elsewhere are tanks of oysters, salmon and paua. OceaNZ Blue, the country’s largest paua farm, is situated on-site, as is a Sealord fa­cility for producing mussel spat for the Marlborough Sounds. NIWA has space for further companies, and its seawater-circulation system can soon be upgraded to pump and filter at a rate of 1 m3/s.

In one office is a chart showing the locations of marine farms in southern Europe. There are hundreds of them. Kiwis are certainly no leaders in this field.

“The key to New Zealand aquac­ulture is our clean green image,” says Bruce. “People overseas have a high regard for our produce because of that, and aquaculture here has great poten­tial. Marine farms can deliver precise­ly specified fresh product rich in those magic omega 3 oils—10,000 3–4 kg salmon on a particular day. Also, fish farming is very productive. A good example is New Zealand King Salmon Ltd that produces over $60 million of premium salmon from only 60 ha of ocean floor space.

“Nothing else comes close to that.”

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