The fishing industry is on high alert as the toxic algae crisis that has been devastating South Australia’s coastlines now cripples businesses.

Kangaroo Island’s tourism businesses are experiencing financial losses reaching tens of thousands of dollars, while across the York Peninsula, oyster farming businesses are currently in quarantine.

Footage shows the waters off Kangaroo island with not a single fish in sight.

Sean Pearce operates fishing charter business Emu Bay Fishing from the island and says it’s “the worst he’s ever seen it”.

With fish numbers declining, he has been forced to anchor up.

Business on land is suffering too.

“We decided to cancel the charters and refund everyone that was booked in that we had, so that was a huge financial loss,” Vicky Pearce said.

“The local restaurants and cafes that sell fresh fish, who use fresh fish in their menus, they are unable to access local fish.”

Across the gulf, oyster farmers in Stansbury are dealing with a double hit.

The algae bloom and another new toxin has forced the bay into quarantine.

Farmer Steve Bowley $500,000 worth of his stock was at risk.

“If it goes much longer I think we as an industry are going to be in a lot of trouble,” he said.

The outlook for South Australia’s fishing sector appears uncertain, prompting calls for government intervention to offer support, such as lowering the licensing fees for industry operators.

“In this time anything helps, when you aren’t earning any money,” Ms Pearce said.

The government said it was watching the situation closely, but there was no word on a support package.