Marine ecologist warns of ‘tipping point’ if overharvesting of sea life from Auckland beaches continues

A Muriwai resident says scalpers regularly fill buckets with hundreds of undersized mussels.

• A University of Auckland marine ecologist says overharvesting of sea life could damage local ecosystems.
• She said the decimation of “ecosystem engineers” mussels could damage the food chain.
• Residents have been raising the alarm about the scalping across beaches in North and West Auckland.

A marine ecologist warns there could be “some sort of tipping point” if damage from over-harvesting sea life from beaches continues.

Residents of Auckland beaches have been sounding the alarm about extreme levels of scalping across beaches in the region.

In January, Muriwai resident Mark Evans told the Herald people were coming and picking off everything from the rock, even starfish.

“You’re only supposed to take 25 [green-lipped mussels], but you hit them up, and they have a full bucket of 80-100. Anything that moves, it’s going to be in the bucket,” he said.

University of Auckland research associate Emilee Benjamin said overharvesting coastal and rocky reefs could limit the ability of marine life to recover.

“As a result, if we take too much, particularly if it’s in high volumes all at once, it strips the rocks and takes the ecosystem out,” she said.

“It could limit the future recovery of those organisms and that ecosystem, especially if there is some sort of tipping point.”

Benjamin described mussels as “ecosystem engineers”.

“They are a foundational organism that a bunch of other organisms will live among or feed upon,” she said.

“If we are scraping the rocks of that type of engineer, it can reduce the recovery and have impacts up the food chain.”

University of Auckland research associate Emilee Benjamin says scientists are still seeing the effects of mass mussel overharvesting in the Hauraki Gulf and the Marlborough Sounds in the late 1970s.

‘Race to the last mussel’

On the west coast, Muriwai Environmental Trust chairman Richard Wright told the Herald overharvesting has become a serious problem since Muriwai reopened after the cyclone.

“It is a race to the last mussel right now. There have been reports of people with large jars shucking mussels on the rocks.”

In northern Auckland, residents say people are using piano wire and building tools to strip sealife from local beaches, doing irreparable damage.

“[There are] buses of people arriving with buckets, with tools, piano wire and going from one pool to another and taking anything and everything that moves. Including things like seaweed,” Army Bay resident Mark Lenton told the Herald.

Meanwhile, Ngāti Manuhiri Settlement Trust chief executive Nicola MacDonald said the damage on North Auckland beaches was extensive.

“The removal of marine and shellfish from low-lying rock pools can devastate marine life, which is unlikely to return and grow. A prime example is the mussel rocks at Pākiri Beach, which are completely devoid of mussels due to scavenging,” she said.

“We’re concerned because we know that coastal marine life plays an important role in healthy marine ecosystems, providing habitats and sources of food for insects, small fish and seabirds.”

Benjamin said scientists were still seeing the effects of mass mussel overharvesting in the Hauraki Gulf and the Marlborough Sounds in the late 1970s.

“The ecosystem has yet to recover. We still see barren shorelines which used to be covered in green lip mussels,” she told the Herald.

However, she said regeneration was possible with greater enforcement and better education.

“I’m not completely against hand-picking,” she said.

“There is a really important balance. There is a beach in the South Island called Ōkiwi Bay. I see people hand-picking from the beach all the time.

“But they are local residents or who have had vacation homes there for years, and the mussel population is very healthy and has great biodiversity.”

David Williams is an Auckland-based multimedia journalist who joined the Herald in 2023. He covers breaking news and general topics.

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