Marine – From mussels to mud

News that thousands of litres of sewage overflowed into the Mahurangi River after recent heavy rainfall is another gut punch for local oyster farmers and the wider marine environment. Couple that with the recent closure of the inner Hauraki Gulf to commercial and recreational crayfish harvest and it’s hard not to long for the good ol’ days.

But what were the good ol’ days? For some it was coming home with half a dozen scallops and crayfish from the local bay, while younger generations may have never seen a crayfish within the Gulf.

The Hauraki Gulf was once a thriving, living ecosystem, home to vast beds of green-lipped mussels so extensive they could filter the entire marine area in just 36 hours. These beds weren’t just abundant, they were vital to the health and clarity of the water, acting as a natural filtration system that supported everything around them.

By the end of the 1960s, industrial dredging wiped out more than 500 square kilometres of mussels from the Gulf, leading to a total collapse in the population.

The Colville Channel was once known for its flush, abundant scallops, while pipis used to line the sandbanks across the Gulf. Today, they are all but gone, and the habitats that supported these have been ground into lifeless mud.

And what happened to the summer flocks of terns and gulls feeding over schools of trevally and kahawai?

The aftermath of that destruction is what people see today, and some believe it’s always been this way. But it’s hard not to believe that when that’s all you’ve known. This is an example of shifting baselines, where each generation inherits a degraded ecosystem and accepts it as normal.

David Attenbrough’s recent documentary ‘Ocean’ gives us an insight into the destructive nature of trawling and dredging. These industrial methods act like bulldozers on the seafloor, crushing habitats, killing non-target species and disrupting the foundation of marine life.

You don’t have to go far to find a plethora of scientific studies showing that trawling and dredging significantly reduce biodiversity and biomass. In many cases, the affected ecosystems never fully recover.

Add to that the untreated wastewater and land-based run-off pouring into our harbours and it’s no wonder the inshore marine environment is struggling to survive, let alone thrive. We’re now witnessing the consequences this can have on the marine environment, local businesses and communities.

For decades, LegaSea and the New Zealand Sport Fishing Council have advocated for holistic management of the Gulf, one that addresses what’s happening on the water and on the land. We’ve been calling for government support to enable commercial fishers to transition to using lower impact fishing methods and stricter controls on discharges from land to the sea.

It’s time to restore the balance so future generations can see crayfish, hāpuku and scallops in the wild and not just hear about them in our stories. With your support, we’ll keep fighting to turn those calls into action.

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