A surfer has been bitten by a shark, the fourth attack along Australia's New South Wales (NSW) coastline in under 48 hours.

The 39-year-old man suffered minor cuts after a shark bit through his board near Crescent Head on Tuesday morning. He is currently in hospital in stable condition, say reports.

This incident follows three other attacks in Sydney over the past two days. All beaches in Sydney's northern area will remain closed until further notice, according to police.

Authorities attribute the recent spike in attacks to days of heavy rains, which may have created a perfect storm environment for shark activity. Rain flushes nutrients into the water, attracting sharks closer to shore.

The attack on Tuesday took place near the Point Plomer campground, about 450km (279mi) north of Sydney. Steve Pearce, the chief executive of Surf Life Saving NSW, stated that the surfer was very fortunate to not have sustained any serious injuries, according to ABC.

Pearce emphasized, We really strongly advocate that nobody swim or surf near river mouths because it's obviously an area where sharks congregate. If it's dirty water I'd think twice about going in there.

A similar incident occurred at Dee Why Beach in Sydney on Monday, where a young surfer narrowly escaped injury. Conversely, a shark attack at nearby Manly later in the day left a 27-year-old with life-changing injuries, and a 12-year-old boy was critically injured at a Sydney Harbour beach the previous day.

Authorities believe bull sharks may be responsible for multiple recent attacks. Bull sharks, found in both fresh and saltwater, are classified as one of the more dangerous shark species, ranking as the third deadliest according to the International Shark Attack File.

Though Australia is renowned for shark activity, the likelihood of a shark encounter is still minimal. Following the attacks, police have advised the public to avoid waterways due to decreased water quality and visibility from recent weather conditions.

Superintendent Joseph McNulty stated, I would recommend not swimming in the harbour or other river systems across NSW at this time.