Marlborough paua diver Phil Walker uses starfish to prompt paua to spawn and claims it has boosted stocks of the shellfish significantly.

A pāua​ diver claims he has accidentally discovered a way to make the shellfish delicacy spawn during harvest and boost pāua numbers significantly.

Phil Walker fishes commercially in what is known as Area 7, stretching from Kāhurangi​ Point on the West Coast to Clarence River on the east.

Walker said his daughter asked him about three years ago to bring a starfish home for her to take to school. The diver said when he put the starfish in with his pāua​ catch, clouds of spawn were released.

"The starfish seemed to stress the pāua​, and they released the spawn," Walker said. "I've been doing it for more than three years now and I'm seeing much bigger stocks coming away in those areas.

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"If you make them spawn and put out millions of 'babies' each time you go fishing it has to make a difference to the industry.

PHIL WALKER Marlborough pāua diver Phil Walker believes pāua can be encouraged to spawn by putting a starfish in with them.

"I'm seeing pāua​ in places I've never seen them before - I haven't seen the biomass so good for 40 years, so much young stock coming on. Even in Tory Channel. Everywhere I fish I spawn and it's quite unbelievable in places.

"The females give out the spawn and the males all clump together and fertilise the eggs. It's a no-brainer."

Walker said researchers had talked about studying his approach and he hoped they would finally take him seriously.

PHIL WALKER Pāua diver Phil Walker puts starfish in with his pāua to make them spawn, which he claims boosts numbers.

"I know it works but the scientists are still doing re-seeding. They've been doing that for 15 years and it never worked. Why would it suddenly start working now?"

Walker made a DVD of the spawn stimulation and circulated it to other divers in Marlborough, Kaikōura​ and Dunedin who had started doing it. He said marine scientists had not studied his findings and could not support his claims.

Pāua​ Industry Council scientist Tom McCowan confirmed Walker's spawning approach had not been studied, and said it should be looked at.

PHIL WALKER Scientists say the idea of scaring pāua with starfish to make them spawn needs put to the test.

"I've spoken to Phil about it. It's quite a controversial one and the short answer is we don't actually know if it works, but there's a chance it might do," McCowan said.

"We've been interested in testing whether stressing pāua​ with starfish releases viable gametes [reproductive cells] to increase recruitment, but that hasn't been done yet.

"Most of the people we've spoken to who have experienced spawning pāua​ in a hatchery, their impression is when you spook a pāua​ with a starfish it's generally just a release of fluids, like a flight or fight-type response, that might not be viable gametes," McGowan said.

"But in saying that we haven't tested it so we don't know. Phil is certainly adamant that it works.

"It is interesting and we need to have a proper look and test it. The first thing we need to do is get some pāua​ in a tank, scare them with a starfish and see if the stuff they release is actually viable. It's been on the to-do list for a while but we've had other stuff happening," he said.

Aquaculture scientist Dr Norman Ragg, of Cawthron Institute, said he was aware of Walker's efforts, and it merited more research.

"I struggle with the automatic assumption that seeing good recruitment in an area is a direct result of [Walker's spawning] process causing it to happen," he said.

Ragg said it would not cost a lot to set up a research base with the divers themselves.

"To get real buy-in you first need impartial observation. My preference is to then hand that back to the divers so you have trained individuals in the industry who know what they're looking for," Ragg said.

He said divers like Walker who were interested in improving their industry could provide research that would cost "tens of millions of dollars" for scientists to replicate.

"This falls into that category. The people who are out on the water looking at the pāua and catching them, and have that intuitive inspiration for their animals, it gives them one more tool.

"It's certainly time for someone to come out and support this."