More Fish and Clean Water!  Amazing Project to Re-Mussel the Firth of Thames. 

What if we could re-mussel the bed of the Firth of Thames to provide a habitat for juvenile fish and larger species like snapper, to filter nasties out of the water and reduce sediment?   Leading to our grandchildren and their children experiencing the kind of biodiversity and abundance our grandparents enjoyed. That is what the Revive Our Gulf project aims to do.

  Since the project started in 2013, an incredible 220 tonnes of green-lipped mussels have been deposited on the seafloor at 3 sites.

image courtesy of Revive Our Gulf

At the turn of the 20th century, the inner Hauraki Gulf was carpeted with over 600km2 of sub-tidal, soft-sediment kūtai (mussel) beds.  

image courtesy of Revive Our Gulf

From 1910, the inner Hauraki Gulf was dredge fished for green-lipped mussels.  By the 1960’s the mussel fishery completely collapsed.  1,500km2 of the inner Hauraki Gulf seafloor was scarred by dredging. Over 50 years have gone by, and the reefs have not recovered on their own. 

Adding to the pressures, sediment and nutrient run-off from years of poor land management practices has turned much of the Firth’s seafloor into a mushy mess.   Below the waterline, there is a biodiversity crisis.

Kōura (crayfish) are now functionally extinct in the Gulf. Without them, and with fewer large snapper, kina populations have exploded, turning kelp forests into barrens. Marine scientists describe an ecosystem on the verge of collapse.

image courtesy of Revive Our Gulf

Why mussels?

These brilliant bivalves reduce sediment and filter out heavy metals such as excess nitrogen and harmful bacteria, resulting in cleaner, clearer water.  They provide a home for tiny critters and a nursery habitat for juvenile fish.  They provide food for crustaceans and larger species like tāmure (snapper) and rays. 

Once established, these mussel beds have become a sanctuary for marine life attracted by the healthier water. There has been a noticeable increase in fish and invertebrate activity as a result, including the return of kingfish, juvenile snappers and mackerel.

The Revive Our Gulf project is a collaboration between The Nature Conservancy NZ, the University of Auckland Institute of Marine Science and the Mussel Reef Restoration Trust. The project plans a network of restoration sites across the Hauraki Gulf to support the research on how to achieve mussel reef regeneration ‘at scale’.

Learn more about the project in these videos –

5 thoughts on “More Fish and Clean Water!  Amazing Project to Re-Mussel the Firth of Thames. 

  1. This is amazing. Will we be doing this in the Firth of Thames? Should we be saving our mussell shells for it?!


    • WRC have not approved fin fish farming. It is subject to a resource consent hearing by independent commissioners and any decision they make can be appealed to the Environment Court and higher courts.


  2. This sounds like a wonderful idea and something I am all for. My question is “You mention that the Revive Our Gulf Project is a collaboration between two groups – The Nature Conservancy NZ and the University of Auckland Institute of Marine Science and the Mussel Reef Restoration Trust, where is the Hauraki iwi in all this? Why have you not got them involved as a major party in the revival of Tīkapa Moana?


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