Mahurangi Oysters

October 2014

Oyster farming, marketing and tourism in Mahurangi Harbour

Andrew and Lisa Hay began farming oysters from the Mahurangi Harbour in 1991. Andrew has a background working on trout and scallop farms in the UK. On his return to NZ he completed a marine biology degree at Auckland University. Andrew says the opportunity for him and Lisa to live and work near the ocean (and raise a family in a beautiful environment) was a strong influence on the decision to set up business.

Pacific oysters originated from Japan and arrived in New Zealand in the 1950’s.  The oysters are farmed in the Coromandel Peninsula, Bay of Plenty, Northland and Marlborough Sounds.  Wild spat is collected on timber sticks, which are placed on inter-tidal racks. Hatchery spat is placed in baskets, mesh trays or bags for on-growing. Most spat is currently wild caught.

Exports of Pacific oysters from New Zealand was about 1,804 tonnes in 2011.  The combined domestic and export value of Pacific oysters was $24.6 m (2011), with exports making up two-thirds of the value ($16.6m). This is produced from farms covering about 1,100ha.

Key cultivation areas are in northern harbours and include Whangaroa, Parengarenga, Mahurangi, and Kaipara Harbours.  Other important areas are the Coromandel Peninsula and Ohiwa Harbour.

Andrew and Lisa farm Pacific oysters (Crassostrea gigas) in the inter-tidal zones of the Mahurangi River. They supply fresh oysters live and whole but don’t sell oysters between January and March as this is the growth/recovery period and oysters eaten during this period are less appealing.

Andrew says there are distinct seasons with oysters:

  • April – September : they are crisp, meaty and plump.
  • October – December : they are fat and creamy.
  • Jan – March : this is the recovery phase for oysters where they are thin and less appealing.

The oysters are taken off sticks on the farm and put into a tumbler on the harvesting barge to be cleaned. They then are taken back to land to be sorted. Oysters are then put into growing-on baskets and taken back out to the farm for a minimum of two weeks. They are then brought back to base, sorted and sent out in poly-boxes.

Andrew has spent a lot of time interacting with customers, showing them how to shuck oysters. He believes you get a far superior product by leaving the oysters in their shells until they’re ready to be consumed.

The OsHV-1 oyster herpes virus was first described in New Zealand in 1991 and was estimated to be costing the industry about $15 million per year in 2010.  Infection is spread by spat movement and movement of equipment.

Mortalities from the virus caused about half of the animals to die during November and December 2010. On some farms up to 80% of juvenile oysters died from Whakatane and northwards.  After the disease outbreak in Mahurangi, Lisa and Andrew wondered if their business would ever recover. But it has, and they are back in full swing, having made the transformation from being a small exporter to a significant local supplier.

“At its absolute worst, we were down to about 30 per cent of our normal stock,” says Lisa.  “But things have improved significantly. We worked a lot smarter and a lot wiser during what would otherwise have been quite difficult times.” These days they produce about 50,000 dozen Pacific oysters and sell all over the North Island.

They have an online ordering business and also used to sell at the local farmers markets but they’ve decided they’d rather have people coming to visit them in their environment.

They’re about to launch oyster farm tours on a purpose-built barge. They’ve only just taken on the job of refitting a barge to take visitors out to the farm. They will harvest and shuck oysters on the barge and Andrew will give guests a guide to the farm and harbour. Andrew says after 20 plus years working on the farm it is nice to step back a little and show people around.