The National Institute of Water and Atmospheric Research (NIWA) attained a five-year research programme funded by the Ministry of Business, Innovation and Employment (MBIE). The research is investigating how the ability of marine ecosystems to support juvenile fish nurseries has been impacted by human activity. This includes whether juvenile fish bottlenecks are being created, whereby there are not enough good quality nursery habitats to nurture sufficient fish to maintain adult populations. The research programme focused on identifying these bottlenecks and creating new options to increase adult fish population sizes and fish stocks.

G.I.F.T. funding was granted to NIWA to map several seafloor areas where juvenile fish live, to learn more about what they need to stay healthy and make it to adulthood. The habitat-mapping of key nurseries used multibeam echo sounder technology on board the NIWA research vessel Ikatere.

Multibeam echo sounders work by sending out a fan of acoustic beams or sound waves directed downwards from the bottom of a boat. These beams reflect off the seafloor, enabling seafloor habitat to be mapped in extraordinary detail. These maps show both habitat types (e.g. reefs, muds, sands, gravels, horse mussel beds), and the wider seafloor landscapes in which they occur.

NIWA created visually appealing maps to engage the community and assist their Technical Advisory Group to advance new management approaches.

A significant finding from the seafloor mapping was the identification of two areas of high biodiversity and important habitats, dominated by three-dimensional calcareous tubeworm patch reef fields. One of these areas falls within the Waikato Regional Council’s region, and is being picked up as a significant ecological areas, with this evidence going to support Council Plans. The other falls in the Auckland Council’s region, who are also likely to zone these habitats as sensitive and to be protected.

The research has identified areas that can’t be put into aquaculture and require ongoing protection. The next step is to digitise at a fine scale where the actual tubeworm patch reef (many hundreds) fields are. More broadly, these new seafloor maps/data for three areas of the Hauraki Gulf, created through the GIFT funding, are helping to describe what makes good juvenile fish nursery areas and where they are found (key things being higher fish densities, higher growth rates, lower mortality rates, and significant subsequent contributions to adult population numbers).

The Ministry of Primary Industries is working on habitats of particular significance to fisheries, and as fisheries move to an ecosystem-based management approach NIWA’s research will come to the fore.

Next steps

Research findings and their implications are being written up and shared. These findings provide evidence for the protection of rare habitats and inform the identification of Marine Protection Areas (MPAs) and other management strategies.

Findings from this research will also support decision-making about activity and protections in the Hauraki Gulf through the networks of the Technical Advisory Group (TAG). The information will also be available to iwi to inform their planning and decision making.

NIWA are applying to MBIE for a significant research programme from 2023 focused on ecosystem-based management of fisheries and their supporting habitats in the Gulf. If the proposal is successful, six iwi are likely to be involved in this programme, with a Māori panel to guide the programme in terms of tikanga and Mātauranga which is semi-autonomous. Māori will also sit on the overall governance group and the Technical Advisory Group. Iwi will participate as part of teams and in the fieldwork. NIWA expects to hear about the success of this research application in late 2022.