Climate change and our iconic Bluff oysters

Sam Heenan on a boat

Our Vision Mātauranga programme has recently awarded four Masters scholarships in research that will help achieve Vision Mātauranga goals. Scholarship recipient Sam Heenan (Ngāi Tahu), studying at the University of Otago, describes his research into the impact of climate change on New Zealand’s iconic Bluff Oyster.

I always wanted to move to Dunedin for university, well before I knew what I wanted to study. At high school I enjoyed biology subjects, so I looked at what there was to study in that area at Otago. I decided to major in Aquaculture and Fisheries, as I’m a keen fisherman and diver, and have always been interested in fish populations. I never saw myself doing scientific research, but I found the practical aspects of the course really interesting, and I got on very well with classmates and staff.

This led me to a decision to do my master’s in marine science, researching Bluff Oysters. The research is very hands-on, and it’s rewarding to contribute knowledge to an iconic commercial species.

I’ve always had a natural desire to learn more about the ecosystem. My experience fishing and diving in the outdoors means I’ve always wanted to know more about the species I’m targeting, as it helped me catch more! Sustainably harvesting these natural resources is important to me, so that they can be preserved for the benefit of the future. More knowledge is often needed in order for management to make the correct decisions around conserving our resources, and it’s rewarding to contribute science towards this.

I’m looking at the reproductive cycle and condition of the Bluff Oyster, and how this is affected by temperature and infection by the Bonamia parasite, during the course of the year. It is important to learn more about reproduction, as breeding determines the future health of the population. Oyster breeding is known to be closely in tune with yearly temperature cycles, and more knowledge about these links is needed to predict how warming oceans may impact the production of oysters in the future. Currently, a major problem in Bluff Oysters is infection by the Bonamia parasite. My research involves looking at how the parasite may affect oyster reproduction. Future management may need to consider how infection rates are altered in a changing climate, and more knowledge around interactions with the parasite is needed.

The Bluff Oyster has long been an iconic commercial and cultural species in New Zealand. Ngāi Tahu holds a significant portion of quota in the Bluff Oyster fishery. I hope that learning more about oyster reproduction, which is a key aspect in determining future population levels, may help an important Māori business to continue sustainable operations. 

In general, I hope my research will contribute more understanding to assist in future fisheries management. The Bonamia parasite is a threat to both aquaculture and the oyster fishery. More knowledge about how the parasite affects oyster breeding and condition may help to more effectively manage the disease. In addition, learning more about the links between temperature, breeding and infection may provide insight into the health of the population in a changing climate.