It's been five years since 83 marine sanctuary zones were implemented in South Australia, and despite ongoing controversy and a lack of conclusive results, proponents maintain it is a step towards fish sustainability "thousands of kilometres" away.

Key points: Questions linger over benefits to fish stocks

Questions linger over benefits to fish stocks Insufficient time to draw conclusions

Insufficient time to draw conclusions SA fishing management among the world's best

The SA Marine Parks Five-Year Status Report, released Monday, concluded insufficient time had passed to detect changes in the size of fish, abundance or diversity of biota within the zones — all with the exception of Cape de Coudecic where rock lobsters had increased in size and abundance.

"The marine parks have only been set up for five years and you need a reasonable amount of time, given the long life histories of some of these species, to have passed before you're going to see increases in size, abundance and diversity," Professor Bronwyn Gillanders said.

"It's essentially just establishing baseline information that you can use to assess change."

Professor Browyn Gillanders believes more time will reveal the benefits of SA's marine parks. ( Supplied: Browyn Gillanders )

The zones are contained within 19 marine parks that stretch across SA's coastline.

The report indicated that biodiversity and ecosystem function was being maintained in the sanctuary zones, with some of the most critical including islands off the Eyre Peninsula and the West Coast.

Other notable areas included the Sponge Gardens sanctuary zone off Kangaroo Island, where the report said vulnerable species, such as the blue groper, harlequin fish and blue devil, found refuge.

Professor Gillanders, from the University of Adelaide School of Biological Sciences, said the purpose of marine parks was also to contribute to replenishing stocks outside the zones, including areas that were commercially fished.

"If we can get larger fish in the marine parks, which is what you're aiming to do by not removing fish species, essentially, they can contribute more in terms of reproduction," she said.

"Some of them can travel thousands of kilometres, depending on their life's history, the length of their larval life. Most fish have a pelagic or larval period when they're in the water column [currents] and that's where they're dispersed.

"Some might only have larval periods that are weeks, others might be a couple of months, and that way you get them moving different distances and that's the idea around having sanctuary areas that are connected to one another."

Fishing communities remain 'unconvinced'

SA Abalone Association president Jonas Woolford said opposition remained strong among regional communities and any spill over would only benefit certain species.

He said those fish spawning pelagic larvae in the right area might move out, but not all species were migratory and remained in certain areas.

"Take, for example, abalone. It's very localised in terms of replenishing, so that's not the case," Mr Woolford said.

A dive survey was undertaken in a SA marine park ahead of the report. ( Supplied: SA Government )

When the zone plan was announced it prompted fears from local communities that commercial fishing would be negatively affected, along with recreational fishing and the tourism it attracts.

This week's report said the price of local fish had remained stable, commercial fisheries had maintained their catch and value, and recreational fishing participation rates had remained stable.

But Mr Woolford said his industry had been affected "quite a bit" by the zones because it lost access to the offshore islands where a lot of the harvesting took place.

He said at least one abalone family at Elliston on the Eyre Peninsula had to "get work elsewhere" and it subsequently affected the throughput of a fish processing factory at Streaky Bay.

Mr Woolford also said charter fishing boats had been affected by the sanctuary zones and had not been replaced by nature-based tourism.

"They talked about this being the greatest thing for ecotourism, which hasn't happened.

"That transition hasn't happened. It's not your Great Barrier Reef. It's not your Ningaloo Reef. People aren't going to come down here and do that."

He agreed the preliminary report had simply established a baseline, pointing out that it should have been established before the sanctuary zones were implemented.

"South Australia has the best fishing management in the world. I fortunately got to travel around last year on a Nuffield [Australian Farming] Scholarship and I was away four months testing that assumption and concluded that it's true," Mr Woolford said.

"And all the while, this seafood harvesting has been taking place in areas that have now become marine parks, so nothing's changed as such, other than we can't have access to it.

"They've been highly productive areas and well managed because of that."

The Nuyts Archipelago Marine Park in the Great Australian Bight is home to the blue groper and Maori wrasse. ( Supplied: The Steve Irwin )

Wild fisheries catch 'stagnating'

Professor Gillanders also believed Australia's fish stocks to be some of the best managed in the world.

In general volume terms, the wild fisheries catch had "stagnated" worldwide due to increasing aquaculture production, particularly in China.

"Marine parks have been set up around the world for a number of years and often there's quite a lot of opposition," Professor Gillanders said.

"People are worried they'll be shut out from fishing and those sorts of things, but after a number of years, the biggest advocates are often the community because they can see the benefits.

"There's starting to be a number of reviews coming out suggesting that it can take a reasonable number of years to start seeing positive effects.

"I think it's about 10 years, but you only see that if your marine parks are a reasonable size and networked to other marine parks."

A 10-year review of South Australia's sanctuary zones is legislated to occur by 2022.