Commercial aquaculture could increase

21:38, Dec 17 2013
Shellfish Production
MUSSEL LINE: Commercial shellfish production adds around $100 million to Auckland’s economy.

Boaties and beachgoers could be vying for space with commercial aquaculture operations around the Hauraki Gulf's eastern shores, harbours, and inner islands under the proposed Auckland Unitary Plan.

With half the country's commercial oysters and a quarter of green mussel production coming out of the area, aquaculture is already a big earner in the Gulf.

But under the proposed plan this has the potential to expand significantly as new commercial aquaculture ventures will become a discretionary activity in much of the Hauraki Gulfs marine area including the Firth of Thames and around inner islands because of coastal classifications.

Shellfish Production
SNAPPER HAVEN: Fishing from Snapper Safari charter boat among the Coromandel mussel farms.

Under the unitary plan most coastal areas have been designated as having high natural character rather than outstanding natural character. An outstanding classification has a much higher level of protection.

But few coastal areas in Auckland have been designated as being of outstanding natural character and the difference could be important.

The outcome of a Supreme Court appeal by the Environmental Defence Society (EDS) over a Marlborough Sounds salmon farm application could see the end of aquaculture in areas with outstanding natural landscape.


New Zealand Coastal Policy Statement is the overriding document surrounding coastal use and development and the EDS says it has been misinterpreted, allowing aquaculture to be developed in areas that have outstanding natural character.

''We contend that on a correct interpretation of Policies 13 and 15, the Board, having found that the site [in the Marlborough Sounds] was an outstanding landscape and had outstanding natural character, should have declined approval.'' EDS Chairman Gary Taylor.

''We are also arguing that the applicant failed to properly assess alternative sites,'' he says.

The Supreme Court judge has reserved his decision.

Aquaculture around the country's marine areas has become a thorny subject for many.

Recent plans for expansion of oyster and mussel farming and the potential for sea cage based yellowtail kingfish farming in northland have brought an angry response from many other coastal users citing visual, navigation and environmental concerns.

That type of objection also came to former Auckland Regional Council aquaculture proposals some years ago for the southern Kaipara Harbour. Expansion and applications for new farms cases in the Marlborough Sounds has seen public protests and numerous court cases.

Aquaculture along Auckland's east coast is limited to around 100 hectares of oyster farming in the Mahurangi Harbour, 40ha oysters and 15ha of mussels off Waiheke, 30ha of mussels around Great Barrier Is and 50ha of mussels near Orere Pt in the Firth of Thames.

On the other side of the Gulf on the Coromandel Peninsula shellfish farming covers around 1,400 hectares much of it mussels in Wilson Bay in the Firth of Thames with a further 520ha expansion recently granted. It's estimated to bring in $48million to the Waikato region including $6 million from Pacific oysters.

Areas totalling around 300ha have been approved for fin fish farming through parliament and have been zoned in the Waikato District Council's District Plan recently, Coromandel Marine Farmers Association executive officer Tom Hollings says. The council calling for tenders on the farming has delayed their development at present he says.

Fin fish farming is expected to create 354 new jobs and add over $34 million to the Coromandel region.

There are environmental concerns around fin fish farming, particularly from fish food and faeces damaging the seafloor under cages and altering surrounding marine ecologies.

Shellfish farming is seen as the least damaging of coastal aquaculture. Shellfish are not artificially fed rather filter feeding their food from surrounding seawater. Collecting sediment on the farm structures is probably the most environmentally damaging effect of shellfish farming.

But expansion of shellfish farming in the gulf does have benefits National Institute of Water and Atmospheric Research (NIWA) recreational fishing expert Bruce Hartill says.

Massive mussel reefs once found on the floor of the Firth of Thames could have filtered the water of the entire Firth every day. They were wiped out by commercial dredging 50 years ago and have never returned. It would take the few remaining beds two years to filter this amount of water.

While expanding shellfish farming is unlikely to come close to replacing that filtering power it should help water quality Dr Hartill says.

The farm structures and the mussels themselves are also very attractive to fish, he says. The fish particularly love the plume of material that comes off the lines at harvest time along with the crabs and other seas life that live on and around the lines, he says. The mussel ropes act as a nursery for young snapper, which feed amongst them, and shelters them from predators, much as the mussel reefs would have done.

''So there's a lot of fish and good fishing to be had around the farms,'' he says. ''Waikawau boat ramp in the Firth of Thames is the most popular boat ramp in the areas as the boaties head out around the mussel farms,'' he says.

On the off season some farm owners run fishing charters in their farms from their barges, he says.

But getting balance right could be tricky for council as the visual impacts of increased marine farms which currently add $99 million to the city could also impact on the $950million tourism in the Gulf brings.