Several sharks were also spotted feeding on a school of salmon close to shore on North Avoca Beach where a surfer was attacked last Tuesday, aerial patrol manager Harry Mitchell said.

The Australian Aerial Patrol spotted the sharks about 11am and contacted lifeguards, who evacuated the beaches and deployed inflatable dinghies to herd sharks into deeper water.

The beaches were reopened about 1pm after a second patrol from the air revealed the sharks had dispersed.

‘‘This weekend’s crews noticed an abundance of marine life close to beaches,’’ Mr Mitchell said.

‘‘As well as sharks, various pods of dolphins and a number of stingrays were also spotted during the weekend’s patrols.

‘‘The evidence of schools of fish together with warmer ocean temperatures are generally important factors in attracting larger species of marine life like sharks to the coastline and often close to populated beaches.’’