Iwi and researchers in the Bay of Plenty are in a race against time to stop mussel beds disappearing from Ōhiwa Harbour.
Eleven-armed sea stars are behind a dramatic decline in the harbour east of Whakatane, which was once a flourishing food bowl for local Māori.
"They don't have a brain per se, they just smell their prey and just go to it like zombies," Sustainable Seas researcher Kura Paul-Burke says.
In 2009 there were an estimated 1.2 million sea stars feasting on mussels.
"The sea stars were so prolific that there were five to six layers deep. Behind them was complete devastation of dead mussel shells and in front was lunch."
By 2019 the mussel population had declined so rapidly there were just 80,000 left. It was disastrous not just for the marine ecosystem but also for iwi, for whom mussels are an important and traditional food source.
Te Rūnanga ō Ngāti Awa is on a mission to get the harbour back to where it was.
"What it was like when I was here back in the day. Full of mussels, full of scallops, full of pipis full of everything that aren't there now," Iwi deputy chair Tu O'Brien told Newshub.
The iwi is now working with researchers combining mātauranga Māori knowledge and western science in the hope of revitalising the harbour's mussel beds.
"We have an inherent obligation to our tipuna, the people before us, to get this space and keep this space for the people coming after us - that's what drives us."
So far the results are promising, with mussel lines placed in the harbour showing signs of restoration.
"We have three new mussel beds all in close proximity to our stations so mussels are falling from the lines and recolonising the bottom," Paul-Burke says.
The next challenge is dealing to their predators. One of the reasons the sea stars are so hard to manage is because they can split themselves into two, effectively doubling their population.
And now a Sustainable Seas project is investigating whether that ability to grow lost limbs can be put to good use.
Paul-Burke says the sea stars may have bioactive properties which can heal human wounds or produce highly sought-after marine collagen for cosmetics.
"Any economic value that came from that, could that then come back here to help us to help pay for everyone to better protect our harbour."
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