The South Australian city of Whyalla is bracing itself for an influx of more tourists off the back of the popularity of the annual display of giant cuttlefish spawning.

Facts about Cuttlefish They can rapidly alter their skin colour at will, as camouflage or communication

They can rapidly alter their skin colour at will, as camouflage or communication Have three hearts that pump a green-blue coloured blood

Have three hearts that pump a green-blue coloured blood Speculated that their eyes are developed before birth — allowing them to observe from the egg

Every year between the months of May and August, tens of thousands of colourful cuttlefish make their way to a small section of rocky reef near Point Lowly in the upper Spencer Gulf, about 30 kilometres north-east of Whyalla.

Their chief purpose is to mate multiple times; the females lay their eggs under the protective rocks and by the end of the season the adult males and females die before the next generation hatches.

"It's the only known breeding aggregation of cuttlefish in the world, so people come from around the world to see it," Professor Bronwyn Gillanders said.

Professor Gillanders and her team have been researching the region's cuttlefish behaviour for more than a decade.

Dr Gillanders collects eggs of cuttlefish for testing and to grow them in a lab. ( Landline: Prue Adams )

"When they are at their peak there is literally one cuttlefish per square metre, and I still get excited going and seeing them," she said.

Annual surveys taken since 1998 by SARDI, the South Australian Research and Development Institute, reveal erratic changes in population.

The numbers peaked at just under 200,000 animals at the turn of the century but dropped to around 13,000 in 2013, causing great concern to the region and researchers.

"We were very, very concerned about what we would see the following year," SARDI's senior research scientist, Mike Steer, said.

"It's been remarkable to see how quickly this population can boom and bust and recover."

The population started to bounce back in 2014 and has remained at healthy levels since.

SARDI researchers completed the 2018 count in June, but the figures aren't expected to be released until September.

"All those raw data sheets get worked up and we calculate the estimate and then we do some statistical analysis and ratify," Dr Steer said. ( Landline: Tony Hill )

"We get a good gauge of that population by how long the divers are in the water and the divers were in the water for a very long time this year… so we would expect that the numbers would be pretty healthy this year," Dr Steer said.

Professor Gillanders and Dr Steer both refer to cephalopods, that's cuttlefish, squid and octopus, as "the rock stars of the sea".

"They live fast and die young," Dr Steer said.

"And, like rock stars, they are parading around, trying to get matings, and they're colourful," Professor Gillanders, from the University of Adelaide, added.

With numerous international media teams visiting Whyalla over the past few years, including the BBC several times and National Geographic, Whyalla Mayor Lyn Breuer said the interest would only continue to grow.

The Mayor said even well-acclaimed documentary maker Sir David Attenborough had expressed an interest in covering the cuttlefish aggregation.

"One of the things that is really great about the cuttlefish is that we have always had this reputation of being this dirty old city, industrial city," Mrs Breuer said.

"This is completely different and it has changed the way we look to the rest of the world."

Lyn Breuer mentioned that Whyalla had a reputation as a 'dirty city' and that cuttlefish are changing the view of her town. ( Landline: Tony Hill )

She said the Council had not collated any firm figures on the number of cuttlefish enthusiasts visiting Whyalla, but motels and other accommodation reported high occupancy rates over the winter months.

The Council has supplied signage to the main diving site, and is building a new toilet and change room block.

While the cuttlefish are located only 20 to 30 metres away from the shoreline, so can be easily viewed by snorkelers walking in off the beach, the Mayor said the Council was looking at options such as a glass-bottomed boat or a transparent walkway so visitors not wanting to get wet could still see the cuttlefish in their natural environment.

For long-term owner of Whyalla Diving Services Tony Bramley, the influx of visitors has been an absolute boon.

"We can get thousands of people over the season," Mr Bramley said.

He said during the first CuttleFest in early July, there were more than 400 people in one diving group.

Mr Bramley said that his business has done well in recent years thanks to the cuttlefish and protection in place ( Landline: Tony Hill )

Many visitors go into his shop looking for diving gear and thick wetsuits to protect themselves against the cold gulf water, and he employed three extra staff to cater for their requirements.

"We would be looking after 50 to 80 customers a day, which is very comfortable for us," Mr Bramley said.

The State Government instituted a permanent, year-round exclusion zone for the fishing of cephalopods in the False Bay spawning grounds.

Cephalopod closure area (including squid, cuttlefish and octopus). ( Supplied: Primary Industries and Regions SA (edited) )

A wider temporary ban, which extends to all the gulf waters between Wallaroo and Arno Bay, will be reviewed early next year.

"It just seems to me that whatever protection has been put in place, it is doing the job now," Mr Bramley said.

"The last three years have been very good."

Learn more on cuttlefish during Sunday Landline at 12:30pm.