Australian beaches are seeing a higher-than-usual number of shark bites. There were two attacks in the span of 48 hours in January, and since then, at least four people have been killed and almost two dozen others injured in encounters. Extreme rainfall and warming ocean temperatures due to climate change are driving the uptick.
Water weather
While shark attacks remain very rare, they have been increasing. In Australia, there has been a “gradual rise in encounters,” said Reuters. The country has been “averaging nearly 29 incidents per year over the last decade, up from an average of roughly 16 per year in the 2000s.”
Australia is not the only country seeing more of the aquatic predators. South Korea “counted 46 large sharks in Korean waters by late June, nearly four times the number recorded at the same point last year,” said The Independent. There have also been an increased number of shark sightings in the U.S., even though summer has just started.
The January attacks were predicted to be caused by a deluge “which broke January daily rainfall records for Sydney” and “flushed sewage and other waste into the nearby coastal waters, attracting baitfish, which in turn lured sharks closer to shore,” said Scientific American. Heavy rain also causes increased sediment, especially on coasts. The sediment “reduces water visibility, making it more difficult for sharks to see and avoid people.”
Along with increasing rainfall, climate change is warming the oceans, which changes shark behavior. Fatal shark attacks are usually because of bull sharks, tiger sharks or white sharks. All three species tend to prefer warm water and stay longer in those waters during summer.
The sharks’ range is growing as the ideal water temperature is encompassing a larger region. There may be increased shark sightings this year in the Pacific Ocean as well because of the super El Niño bringing warmer-than-usual water temperatures. Sharks that bite people have “often mistaken a human for a seal” or the bites “can be exploratory” or to “ward off imagined competition for food, such as a school of fish,” said The Guardian.
Spotting and culling
To prevent human-shark interactions, Australia has used aerial surveillance to spot the marine animals. “Once drone pilots spot a potentially dangerous shark, they will alert lifeguards, who can sound the shark siren and clear the water,” said The New York Times. The country does currently have a shark culling program, but some are calling for the program’s expansion in light of recent attacks.
However, others have objected. If sharks are removed from a certain area, “that habitat does not cease being suitable,” said The Sydney Morning Herald. “Other sharks will swim in and colonize that area.” Therefore, to be effective, “you would have to remove all the sharks, driving them to extinction or close to it,” which is “not a cull, it’s ecocide.”
“Human-shark encounters are extremely rare” despite the increased number of shark attacks, and “you’re statistically more likely to be killed by lightning,” said Scientific American. Instead, “beachgoers should be ‘shark smart,’” and avoid swimming when the sharks are most active, at dusk and dawn. Environmental factors play a part, but an increased human population along with the growth of water sports and recreation in the ocean have also increased human-shark interactions.
Sharks are not simply deadly killing machines. Their presence may be helping fight climate change. Sharks in coastal waters “ultimately protect and enhance what is known as ‘blue carbon,’ which is “carbon stored in oceans,” said the World Wildlife Fund. “When sharks target plant-eating fish, they can positively impact the marine carbon cycle.”
Rainfall and warming temperatures bring the fish to shore
