Story at a glance

  • Experts attribute the influx of shark encounters to more beachgoers in the water as opposed to sharks lingering closer to shores.
  • Thanks to conservation efforts, shark populations have increased. The species generally migrate to follow their prey.
  • Warming water temperatures may influence future migratory patterns of some species.

For beachgoers flocking to shorelines across the U.S over the summer, many have probably thought about whether they will encounter a shark during their time in the water -- despite it being an unlikely possibility. 

Reports of large quantities of shark sightings along each coast only fuel the flames of the general fear of a shark attack––a term itself that is under fire as conservation activists wish to rebrand the nature of shark-human interactions. 

Speaking with The Hill, marine biologists say that despite the headlines, nothing has really changed in the water.

“It’s summertime, so people are on the coast, and they’re just becoming more observant of the sharks,” said Marine Levine, the founder of the Shark Research Institute headquartered in Princeton, New Jersey. 

While Levine said that the volume of shark sightings can broadly be attributed to more people in the water following COVID-19 lockdowns, some shark populations are increasing––which is a good thing.

“Predators are a sign of healthy ecosystems,” she added, noting that many food sources for some sharks, namely marine mammals, have benefitted from protection orders to conserve the marine ecosystem. If the top predators can thrive, it implies the health of the broader ecosystem.

However, there isn’t much evidence to support that sharks are inching closer to shore. Levine says they are just following their food, be that marine mammals like seals or fish. This explains the more frequent sightings of white sharks around Cape Cod, Massachusetts, and Sandy Hook, New Jersey, where seals are often found. 

Critically, Levine adds that “humans are not on any shark’s menu.”

On the West Coast, Andrew Nosal, an assistant professor at the University of California, San Diego, agrees that sharks aren’t being drawn any closer to shore than they have been historically. 

“I think what we’re seeing now in terms of more shark encounters is mostly due to there being more people outside and in the water,” he said.

Nosal credits lockdowns as a driver in this trend.

“The sharks are always there,” he stated, adding that an influx of people will naturally lead to a greater chance in encounters.

Nosal also points out that the popularity of drones, specifically using them to go offshore and capture footage, makes people much more aware of sharks that have been living off the coasts of the U.S., especially when the footage is broadcast on social media. 

He agreed with Levine and said that the shark population has increased, thanks to the protection of their prey.

“In Southern California, our seal and sea lion population have been increasing over the last couple of decades because marine mammals have been protected since the 1970s,” Nosal said.

Aside from changes in their food source dictating species behavior, both Levine and Nosal say that warmer water temperatures stand to influence migratory behavior. 

Some sharks, such as the Blacktip shark, prefer warmer waters, while others, such as White sharks, gravitate toward cooler temperatures. 

Nosal confirmed that on a long scale, average ocean temperatures are rising, which is due in part to climate change.

He pointed out that while scientists don’t yet know what that means for long-term shark migratory patterns, shorter scale meteorological fluctuations, such as the marine heat waves or El Niño years bring unseasonably warmer waters, which result in sightings of different marine species. 

Data from the National Oceanic and Atmospheric Administration (NOAA) points out that the average global sea surface temperature has increased by about 0.13 degrees Celsius per decade over the past century.

Nosal said that these climate fluctuations can bring tropical species, such as Hammerheads sharks and the occasional Whale shark up from Mexican waters. He said that the rise in long-term water temperature averages is concerning since it can be a harbinger for the coming decades. 

Given the nature of species migratory research, however, Nosal said that it remains to be seen how warmer waters will alter shark migration. Both scientists concluded that the marine ecosystem is so interconnected that it is difficult to predict how one variable will impact another. 

“I just don’t think we know yet what is going to happen long-term,” he said. 

Given the patterns seen during El Niño and marine heatwaves, Nosal predicted that warmer temperatures may push some shark species northward. 

“As the water temperature increases, we might expect to see the range of different species shift northward,” he said.

Still, this movement is highly dependent on what their prey is doing. 

One thing is certain: sharks have been in the water long before humans, but that shouldn’t be any cause for alarm.

Published on Aug 09, 2021