Despite being in the tail end of winter, marine heatwaves are still ongoing in many New Zealand coastal areas.

That is according to Dr Malene Felsing, Moana Project Manager, speaking at the Seafood NZ conference on Friday.

The Bay of Plenty has already recorded the most extended marine heatwave seen in New Zealand waters, a heatwave that has now been ongoing for nine months.

This is according to a new Moana Project site showing the duration of marine heatwaves in New Zealand. And Fiordland had the most impactful marine heatwave on record in 2022, with temperatures reaching almost 5 degrees above normal.

To gain more information, MetService researchers, through the Moana Project, have collated New Zealand's most extensive ocean temperature data, through using sophisticated sensors on commercial fishing gear.

'We have over 250 sensors attached to commercial fishing gear, from inshore cray potters to deepwater trawlers in the Southern Ocean, sending back ocean temperature and depth data,” says Dr Felsing.

'These sensors collected an astounding 4.3 million observations last year, 700,000 alone in the month of June. Altogether, the sensors have been collecting underwater data for a combined time of over 12 years. In 2020 New Zealand had almost no real-time observations of coastal ocean temperatures, and now we have millions – thanks to the fishing industry.”

The ocean temperature data collected will be incorporated into MetService ocean forecasts, improving accuracy.

'From the more accurate models we get better forecasts, including for marine heatwaves, and this is vital information will help us prepare for and mitigate climate change impacts,” says Dr Felsing.

'Fishers get their data back, so they know exactly what the temperature was where they fished. This, along with the improved forecast and warning of marine heatwaves, is the first step in helping fishing and aquaculture industries better prepare for ocean warming.

'Looking to the future, Moana Project research shows that average sea temperatures could increase by 1.4 degrees by 2060, and by almost 3 degrees by the end of the century. This has wide implications for marine life, including fisheries and aquaculture. This means that by mid-century we may be facing 260 days of marine heatwaves per year, increasing to 350 days by 2100.

'We can't measure everything, everywhere, all the time – that is why we need accurate models, coupled with real-time data to forecast both short and long-term temperatures. The Moana Project is unlocking the seas around NZ, providing vital data and information for all industries that use our seas.”

The Moana Project is a Ministry Business Innovation and Employment funded five-year research project that comes to an end September 2023. The project is currently looking at ways to further the ocean observation and forecasting beyond this.