SAN DIEGO — The small coastal city of Del Mar closed nearly its entire stretch of beaches on Sunday after a shark attacked a man participating in a group swim, officials reported.

The 46-year-old man was with about a dozen other swimmers who regularly train in the cool waters north of San Diego when the shark attacked at about 9 a.m., biting his arm, hand, and torso, the city of Del Mar said in a statement. He was rushed to a hospital in San Diego with "injuries that are significant but not believed to be life-threatening," the city added. A hospital spokesperson declined to provide the man's exact condition.

Immediate Response and Beach Closures

The attack occurred approximately 100 yards from Del Mar's relatively new lifeguard headquarters on 17th Street. Lifeguards on duty swiftly closed a stretch of Del Mar beach to swimmers and surfers, one mile north and south of the facility, until 9 a.m. Monday. City lifeguards have jurisdiction along 2.5 miles of coastline, ensuring the safety of beachgoers in the affected area.

Impact on Nearby Beaches

Torrey Pines State Beach, located south of Del Mar, remained open according to its website and phone line. The nearest San Diego city beach, Blacks Beach, known for its popularity with surfers, is more than 5 miles from the attack site and remained open, a city lifeguard official confirmed.

Environmental Conditions

The incident took place under relatively normal conditions for early June, including 3-foot waves and a water temperature of 64 degrees, which still necessitates a wetsuit for most swimmers, according to the National Data Buoy Center.

Tourist Season and Shark Activity

The attack happened during the seasonably cool and cloudy "June gloom" weather, as coastal San Diego County prepares for an influx of tourists, many escaping the intense summer heat of Arizona. Research published in April in the journal Frontiers of Marine Science noted that juvenile white sharks tend to spend more time closer to shore during spring and summer, influenced by "micro-scale" habitat changes, including water temperature.

Shark Species and Attack Statistics

It wasn't immediately clear what kind of shark was involved in Sunday's attack. The Florida Museum of Natural History’s International Shark Attack File reported two unprovoked shark attacks in California last year, one of which was fatal. Florida, with 16 unprovoked attacks, led the U.S. in such incidents, accounting for 44% of the national total and about a quarter of those worldwide.

Historical Context

Since 1926, San Diego County, which includes Del Mar, has recorded 20 unprovoked shark attacks, the highest number among California counties. The predominant activity for those involved in unprovoked attacks is board sports, including surfing and bodyboarding, according to the shark attack file.

Conclusion

The swift response by Del Mar lifeguards and the proactive measures taken to ensure public safety underscore the importance of vigilance in coastal areas known for shark activity. As the region braces for the summer tourist season, local authorities will likely continue to monitor shark movements and beach conditions to prevent further incidents. The incident serves as a reminder of the unpredictable nature of the ocean and the need for continued efforts to ensure beachgoers' safety.