As Memorial Day weekend kicked off beach season in the United States, vacationers on both coasts once again faced reports of shark attacks.

A woman was found bleeding profusely Sunday about 100 yards off the shore of Corona Del Mar State Beach, after receiving large bite marks on her upper torso and shoulder, the Associated Press reported. As a result, miles of the sandy Newport Beach, Calif., shoreline were shut down through Monday. The woman’s condition is unknown, but she was conscious when brought to the hospital. Although there were no eye-witnesses, officials believe the incident to be a shark attack and are treating it as such.

Across the country that same day, a 13-year-old boy was bitten on the calf by a nearly 6-foot-long shark while he was wading in waist-high water in Neptune Beach, Fla., which is about 17 miles east of Jacksonville. Although he suffered severe lacerations, he was in stable condition at University of Florida Health Jacksonville on Monday.

May is “when our sharks become more abundant in our local waters … and the animals peak in abundance around June and July,” Jim Gelsleichter, a shark expert at the University of North Florida, told WJXT.

It’s also the season that statisticians remind beachgoers that the chances of being attacked by a shark are infinitesimal and list all the activities likely to produce far more injuries, from DIY projects at home to bike-riding. For beachgoers, plain old accidental drowning is still the big danger, with some 3,500 fatalities annually in the United States, according to the Centers for Disease Control and Prevention, not counting drownings related to boating.

Still, George Burgess, director of the International Shark Attack File at the University of Florida, told Reuters this year could be a record high for unprovoked shark attacks. If so, it would follow a trend that began last year, when 98 people around the world were bitten by sharks, setting the record for attacks. The previous record, set in 2000, was 88 attacks.

“These are entirely predictable things just as you can predict drownings or car accidents as a result of this being a huge holiday weekend,” Burgess said of the weekend’s incidents.

The reason is simple math: The world contains ever more people, recreational beaches are more crowded and there are more sharks.

According to a 2013 release by NOAA, the U.S. coastal population is predicted to grow from 123 million people to 134 million people by 2020. And that’s to say nothing of the vacationers who visit both coasts’ beaches.

Meanwhile, a 2015 study by the NOAA Fisheries Service found that shark populations have been increasing on the East Coast, an ongoing trend.

“We’ve seen an increase in the number of sharks in every survey since 2001; that reflects management efforts to conserve the populations of various shark species,” Lisa Natanson, the scientist at the Narragansett Laboratory of  NOAA Fisheries’ Northeast Fisheries Science Center who led the survey, said in a news release. The survey samples coastal waters from Florida to Maryland and Delaware, where migratory sharks concentrate as the waters warm in the spring and summer.

The last survey, in 2012, found 1,831 sharks. The 2015 survey found 2,835, which is a 55 percent increase.

Gregory Skomal, a shark expert with Massachusetts’s Department of Fish and Game Division of Marine Fisheries, told Newsweek that shark populations decreased from the late 70s to the early 90s as their meat became more popular. Since sharks grow so slowly and only reproduce a few times in their lives, they are particularly prone to overfishing. But with better wildlife and fisheries management across the country since the 90s, those populations have been slowly recovering.

One last factor that could contribute to shark attacks is how many people are actually spending time in the water. Burgess said as the ocean’s temperatures continue to rise, it will become increasingly attractive for swimmers looking to cool off.

Others said this is already happening.

“More people are using the ocean now for recreation than ever before, so there is no doubt that we’re putting more people in the water,” Chris Lowe, professor in the Department of Biological Studies and the Shark Lab at California State University Long Beach told Men’s Journal in 2014. “You put more people in the water and add more sharks to coastal areas, you will have more shark-human related interactions.”

The good news for the United States is that, while the country leads the world in unprovoked shark attacks, its victims are more likely to live. In 2014, the fatality rate for shark attacks in the United States was 1.7 percent compared to 12.8 percent worldwide, the Atlanta Journal-Constitution   reported.