Dear EarthTalk:

You hear a lot about shark sightings and attacks nowadays; does this mean that sharks are more abundant than ever and doing well overall—or the opposite?

R.W., Welfleet, MA

It’s tough to accurately document shark sightings, but shark attacks are documented every year. There are two classifications of shark bites: provoked and unprovoked. Provoked bites occur after a person has initiated interaction with the shark, like attempting to touch or feed it. But, according to Gavin Naylor, director of the Florida Program for Shark Research, “Unprovoked bites give us significantly more insight into the biology and behavior of sharks. Changing the environment such that sharks are drawn to the area in search of their natural food source might prompt them to bite humans when they otherwise wouldn’t.” 

Globally, unprovoked attacks in 2022 were 57. In 2021, there were 73. During the pandemic, many beaches shut down, but looking at the years preceding 2020, we can more accurately deduce changes in shark attack frequency. Using data from The University of Florida’s International Shark Attack File, the average number of annual unprovoked attacks from 2015 to 2019 was 79.4. Comparing this to 2022, it can be seen that the frequency of shark attacks has not risen significantly, if at all, in the past few years.

In spite of this, due to increasing ocean temperatures sharks are more inclined to travel into coastal waters where tourist activity is common. According to the National Oceanic and Atmospheric Administration, these waters are typically cooler than waters offshore. Warmer waters have higher concentrations of chlorophyll which attracts plankton growth. Many species of fish, rays and crabs feed on plankton. As ocean temperatures rise, northern and coastal waters grow warmer, attracting plankton, fish and other shark bait prey. As a result, sharks are more attracted to these regions than before.

Although the number of unprovoked shark attacks around the world has not increased, regions along the United States’ East Coast have seen upticks in shark incidents. In 2022, there were eight shark attacks in New York after three consecutive years of zero cases. In 2021, Florida experienced 28 shark attacks following a three-year-average of 17.67 annual incidents. Because of these increases, there may be more media coverage on shark attacks, leading people to believe that there are more sharks overall. 

Though shark sightings may be becoming more frequent, shark numbers are dwindling. Many shark species are struggling in their native coral reefs and marine ecosystems. According to the journal Science, “Five of the most common reef shark species have experienced a decline of up to 73 percent.” In addition, The Washington Post states that “a third of all sharks, rays and related species are at risk of going extinct.” As a result, scientists are concerned that species lower on the food chain will overpopulate without the presence of sharks as natural predators.

Humans are responsible for many factors that may be causing a decline in shark populations. Overfishing deprives sharks of one of their primary food sources. Millions of sharks get entangled in fishing nets and longlines ever year. Plus, some 73 million sharks are killed for the shark fin and meat industry.

CONTACTS

• The ocean phenomenon that's bringing sharks closer to shore, wral.com/story/the-ocean-phenomenon-that-s-bringing-sharks-closer-to-shore/20394126/
• Widespread diversity deficits of coral reef sharks and rays, science.org/doi/10.1126/science.ade4884.