Amid long toxic algae blooms, South Australia's sharks have unusually high sightings and strandings, but scientists say it's too early to be associated with the recent shark incident.

A swimmer was bitten by a shark on the Norlonga Beach 30 km south of Adelaide CBD on Thursday, a report reported an increase in shark populations, which it was close to the shore - some people washed something on the beach.

Angel sharks reportedly died on the York Peninsula on Tuesday, adding more than 200 marine species, reportedly killed by poisonous algae blooms, which has affected much of the SA coastline since March.

It is driven by ocean heat waves and the water temperature is 2C higher than usual, scientists say. Due to climate change, such events have become more frequent and intense, causing widespread damage to ecosystems and fish communities

In May, a 3-meter-long white shark died on Henry Beach in Adelaide, after which locals found it struggling in shallow water. It was reported that this was the fourth white shark reportedly stranded and others were found in Willunga, Ardrossan and Aldinga.

Charlie Huveneers, a professor at Flinders University, and an expert on shark ecology and his interaction with humans, said recent shark observations and retention events may be related to the recent algae Bloom.

"We can only confirm this and understand which toxins can cause these obstacles once the toxicological results are restored," he said.

But Huoyi warned that while it may be tempting to link the increased activity to the risk of shark bites, tracking data showed that white sharks occurred throughout the year regardless of algae blossom.

South Australia's Ministry of Primary Industries said that while sharks and other marine organisms affected by the openness of algae are being examined, there is no scientific evidence before the government that algae blooms may make shark attacks more likely to cause shark attacks”.

"The encounter of sharks has always been a small risk for anyone to enter the ocean anywhere in the world," a spokesperson for the department said.

"White sharks use coastal waters to find food, especially teenagers and sub-adult white sharks who are mainly fishermen. They use such nearshore areas to find small sharks, rays and skates, as well as to include larger school-raising fish, including salmon, mull and snapper."

In 2025, the state's marine environment is affected by high water temperatures, insufficient rainfall and prolonged toxic algae blossoms.

"A lot of things have happened and we don't know what impact it has on things like shark behavior right now," said Dr Briana Le Busque, Director of Environmental Science Programs at the University of South Australia.

More broadly, people have witnessed first-hand how these major ecosystem changes affect species, she said. “A lot of talk,” she said.

Le Busque, a conservation psychologist who studies people’s perceptions of sharks, said that as these events occur, public attitudes have changed significantly.

She said the public responded significantly differently when the white sharks were washed on Henry’s Beach. Still have fear, but also care about animals.

“Even before the shallow water area is washed, we see a lot of ordinary people trying to help a person, and many times people don’t necessarily like it.”

Shark bites occurred in January after a fatal shark incident on the state’s west coast. Although such incidents are "absolutely terrible", they are currently in line with the annual average, Le Busque said.