Cuttlefish Numbers Plummet in Spencer Gulf, Impacting Whyalla Tourism

Normally at this time of year, Matt Waller would be taking tourists from around the world to see the spectacle of iridescent cuttlefish in the waters of the Spencer Gulf.

But the tourism operator has not run a single boat tour this season.

The waters off Whyalla are usually teeming with tens of thousands of cephalopoda, as they make their annual migration. This season, however, only dozens have been reported, and Mr Waller believes the algae bloom is to blame.

"It's been devastating to be honest," Mr Waller said.

"We've probably covered the whole reef two and a half times most days to see what's going on and I've only seen one cuttlefish myself."

Marine biologists report the water temperature is at 14 degrees in the Spencer Gulf, a level appropriate for cuttlefish migration, yet there have been very few sighted.

There is no official cuttlefish count by the state government, but marine biologist and dive shop owner Manny Katz said he has recorded a couple of dozen, "which is next to nothing".

Both Mr Waller and Mr Katz's businesses have made the decision to cancel their seasons altogether.

It means the extra casual staff put on for the season will be let go.

Mr Katz said his business is projected to lose $400,000 because of the cancellation, but he wants to "let the cuttlefish be".

"We've seen some [cuttlefish] eggs laid. There's mating activity happening," he said.

"We encourage people not to come, even if they are scuba divers.

"The algal bloom is definitely, in my professional opinion, the most likely cause of the decreased numbers."

Government response

South Australian Premier Peter Malinauskis said "active investigations" are underway by the South Australian Research and Development Institute (SARDI), monitoring the cuttlefish.

"We've always known there was a pretty substantial risk associated with the algal boom. Those monitoring efforts remain ongoing," Mr Malinauskis said.

"The government has spared no expense when it comes to [the] response to the algal bloom, including the protection of the cuttlefish – we were even deploying the bubble curtain to get around the eggs, around the cuttlefish."

That $700,000 bubble curtain was never turned on.

Operators remain hopeful

Whyalla City Council still remains hopeful the cuttlefish will show up, with other operators continuing their services and land-based activities, including the annual Cuttlefest.

A council spokesperson said water temperatures were finally beginning to approach the 11 degrees that cuttlefish find ideal for breeding.

"Even if the cuttlefish don't return … it's still worth celebrating and offering activities for our community, as well as those who have travelled to Whyalla," they said.