City lifeguards yesterday warned beachgoers of a high influx of box jellyfish on O'ahu shores.

Yesterday was this month's anticipated peak influx, with more than 1,800 box jellyfish being spotted on Waikiki Beach by 2:30 p.m. and more than 130 found at Ala Moana Beach Park by mid-afternoon.

Bryan Cheplic, spokesman for the city Emergency Services Department, said 169 people were treated for jellyfish stings by city lifeguards at Waikiki beaches and five at Ala Moana.

Cheplic said paramedics treated a man in his 30s at the beach fronting Duke's Restaurant in Waikiki after the man reported difficulty breathing following a jellyfish sting. He was the only patient who was treated and transported to a hospital due to a jellyfish sting, Cheplic said.

Lifeguards posted warning signs at Waikiki and Ala Moana.