Science Centres: Fisheries

Marlborough mussel farm (Photo Barb Hayden, NIWA)

Recent NIWA research has shown that poor mussel yields in Pelorus Sound between 1999 and 2002 were the result of climatic influences on food supply, not overcrowding.

NIWA has been working with the New Zealand Mussel Industry Council (NZMIC) and the wider mussel industry for the past 11 years to assess what drives variation in mussel meat yield.

Our analysis of long-term data has shown that poor yields in 1999-2002 were linked with climatic changes, not the exhaustion of food supplies by mussel farm expansion.

During the period, southeast winds in La Niña summers resulted in less upwelling and nutrient delivery to the Pelorus Sound entrance in Cook Strait. In winter, lower river flows during southerlies also meant lower nutrient input, food supply, and mussel yield.

This research was carried out as part of NIWA’s Sustainable Aquaculture Project, with funding from FRST and NZMIC and data from the mussel industry. The project aims to understand both environmental drivers of productivity, and environmental impacts of marine farms. Another major part of the project found that New Zealand’s biggest mussel farm in Wilson Bay, Hauraki Gulf, had very little impact on the bay’s ecosystem.