For many years, people who cared about the Hauraki Gulf Marine Park came together at the Hauraki Gulf Forum’s annual seminar. There had been notable success on the Gulf’s islands – predators removed, native forests regenerating, and birds and reptiles returning in large numbers.
The same could not be said for the marine environment. Presentations highlighted declining water quality, sedimentation, seabird bycatch, and whales being struck by boats. The outlook for Tīkapa Moana / Te Moananui-ā-Toi was sobering.
In 2012, the seminar was titled “Charting the Enhancement Pathway.” The closing presentation, delivered by NIWA scientist Darren Parson, offered a different perspective. Drawing on research into historic green-lipped mussel beds – once extensive across the Gulf but long since lost – he showed that when mussels were placed in cages on degraded seafloor, they could survive.
The shift in the room was immediate. What had felt like decline began to look, at least in part, like something that might be rebuilt.
At the close of the seminar, conference organiser Tim Higham invited those present to consider what restoring mussel reefs might involve. More than 25 people stepped forward, forming a multidisciplinary group of scientists, planners, business leaders, council staff, educators, and community advocates.
In June 2013, this group established the Mussel Reef Restoration Trust as a registered charitable trust. John Laurence, who had led the restoration of Motuihe Island, became Chair. Members took on leadership roles across science and technical advice, logistics, planning and regulatory processes, communications, and relationships with iwi and industry.
From the outset, the Trust adopted a “learning by doing” approach.
The University of Auckland became a key partner, bringing expertise in marine science and aquaculture. With much still unknown, research was embedded alongside early restoration efforts.
A doctoral programme, supervised by Andrew Jeffs and Shane Kelly, investigated mussel survival, the influence of bed size, and the development of marine communities across a series of pilot sites.
In late 2013, seven tonnes of green-lipped mussels were deployed off eastern Waiheke Island. Dropped by mussel barge, they formed seven dense, “living room”-sized plots within an embayment. Over time, the mussels bound together across what had been largely barren seafloor and were colonised by a range of marine species.
Despite some initial mortality and expected predation, the beds began to demonstrate the ecological functions associated with mussel reefs.
In 2014, a further 63 tonnes of mussels provided by North Island Mussels Ltd were deployed. Monitoring showed these beds supported a diverse benthic community, including molluscs, crabs, starfish, sponges, and ascidians.
As the work progressed, new challenges emerged. The arrival of the Mediterranean fanworm in the Coromandel introduced significant biosecurity concerns. The Trust was advised by Biosecurity New Zealand that permits would be required under the Biosecurity Act 1993 to continue restoration activities.
Obtaining these permits proved complex, requiring time-consuming and costly procedures such as freshwater treatment of mussels to remove potential contaminants.
Mahurangi Harbour was selected as the next site, in part due to the availability of infrastructure that could support these biosecurity requirements. Early deployments there created biogenic structure and attracted a range of species, including juvenile snapper, koheru, goatfish, spotties, and squid. However, smaller beds struggled to persist, reinforcing the importance of scale in reef development.
In response, larger ten-tonne beds were established from 2017 onwards. These projects were supported by local communities and iwi, and attracted growing public interest.
By 2018, additional large-scale beds had been deployed in Mahurangi Harbour. However, the cost of restoration, particularly under existing biosecurity requirements, remained a significant barrier to scaling the work.
At the same time, efforts to address these constraints intensified. Through sustained engagement, a more tailored biosecurity risk assessment framework for mussel reef restoration was developed. This culminated in Biosecurity New Zealand establishing a specific pathway for restoration activities.
The Mussel Reef Restoration Trust subsequently secured a 35-year resource consent from Auckland Council – an important step in enabling longer-term restoration efforts.
As the work evolved, so too did the organisation. The Mussel Reef Restoration Trust became Revive Our Gulf Trust, reflecting a broader, ecosystem-based approach to restoration and a growing focus on partnership, knowledge-sharing, and enabling restoration at scale across the Hauraki Gulf.
This early work laid the foundations for how we approach restoration today: as a long-term, collaborative effort grounded in experimentation, research, and partnership.
While much has been learned, restoring kūtai reefs at scale remains a complex challenge. The work continues.
