Environment – Million-dollar reefs: the source of NZ aquaculture mussels

The mussels fuelling Aotearoa’s lucrative aquaculture industry come from reefs located around Te Oneroa-a-Tōhe/Ninety Mile Beach. That’s according to Moana Project scientists who have just released their findings after three years of research.  

Dr Romain Chaput, a postdoctoral fellow with Victoria University who conducted parts of the research says: “New Zealand’s green-lipped mussel aquaculture industry is worth 380M annually. The industry is largely reliant on wild-caught baby mussels, known as spat, that wash up attached to seaweed on Te Oneroa-a-Tōhe / Ninety Mile Beach. Until now, we had not identified the source of the spat, and that posed a threat to the aquaculture industry that depends on it.”

Moana Science Lead, oceanographer Dr Joao de Souza from MetOcean Solutions adds, “Knowing the source of spat is important because it means agencies can work with hapū and iwi to establish a regime of protection that will benefit everybody.”  

Dr Chaput explains, “Mussels spend up to six weeks as larvae, which means that they can be transported hundreds of kilometres before they land on the beach. In the Moana Project, we used ocean modelling and genetic analysis to figure out the source of the spat that lands on Te Oneroa-a-Tōhe / Ninety Mile Beach.

“Mussel genetics demonstrate that the spat landing on Ninety Mile Beach are from nearby reefs. The spat from the local area are similar genetically, but distinctly different from mussels from other parts of Aotearoa.”  

Dr Chaput adds that this is supported by the ocean modelling done by the Moana Project. “By tracking particles in ocean hydrodynamic models, we found that the spat landing on Te Oneroa-a-Tōhe / Ninety Mile Beach is most likely to come from mussel reefs off Ahipara and to a lesser extent from Tiriparepa / Scott Point and Hokianga.”

“The research shows that although mussel larvae can theoretically be transported hundreds of kilometres at sea during their month-long journey, we now know that off the west coast of Northland they are not transported very far at all – the spat come from local mussel beds.”

Kevin Oldham, the Chair of the Marine Farming Association R&D Committee adds, “Knowing the location of the mussel beds that the aquaculture industry relies on for spat allows resource managers and communities to safeguard them for future generations.”