Can Certain Weather Make You More Vulnerable to Shark Attacks?

Great White sharks live in the coastal waters of all the world's major oceans. Dave Fleetham, Design Pics/Perspectives/Getty Images

During summer 2015, North Carolina beach towns became Amity Islands with the number of shark bites reported in June alone setting a new state record for the year. It's possible that weather and climate could have been to blame for the spike in shark activity. How, you ask? 

Sharks Like It Saltier With Low Rainfall

One weather type that impacts shark activity is rainfall, or rather, the lack thereof. Without rain falling into the ocean and diluting it with freshwater, the salinity (salt content) of ocean water close to shore becomes more concentrated, or saltier than usual. So anytime there's a dry spell or drought, sharks — which are salt-loving creatures — are drawn closer to shore in greater numbers.

Hot Temperatures Tempt Us Into Their Territory

Ocean waters are a shark's domain. Beaches are our summer vacation meccas. Beginning to see a conflict of interests?

Summer holds the perfect storm of ingredients to bring sharks and humans together. But while summer alone encourages shark-human interactions, unusually hot summers generally guarantee it. Consider this... On an 85-degree day, you might be happy to lounge in the sand and take the occasional two-minute dip in the ocean to cool off. But on a 100-degree or hotter day at the beach, you're more likely to spend the entire day wading, swimming, and surfing in the waves just to keep cool. And if you, along with all the other beachgoers, are spending more time in the water, the chance of someone having a run-in with a shark just increased exponentially. 

La Niña Provides Feasts for Sharks

A shift in wind patterns can also draw sharks to near-shore areas. For example, during La Niña events, the trade winds strengthen. As they blow across the ocean's surface, they push water away, allowing cold, nutrient-rich waters to rise from the ocean bed to the surface. This process is known as "upwelling."

The nutrients from upwelling stimulate growth of phytoplankton, which serve as food for small marine creatures and fish, like mullet and anchovies, which in turn are shark food.

Keeping Your Beach Visit Shark-Free

Besides being shark aware during periods of drought or reduced rainfall, heat waves, and during active La Niña events, take these 5 simple precautions to reduce your risk even further: 

  1. Don't swim at dawn or dusk — the two times of day when sharks are most active.
  2. Don't go farther than knee-deep out into the ocean. (Sharks rarely swim in shallow waters.)
  3. If you have a cut or an open wound, stay out of the water. (Blood attracts sharks.)
  4. If you notice a lot of small bait fish swimming around, leave the water. Sharks feed on them and may be attracted to the area. Similarly, don't swim near fishing piers as sharks can be attracted to fishing bait and fish guts (from caught and cleaned fish).
  5. Keep out of the water when a marine life warning flag or sign is raised — no exceptions!