Shark sightings rise as Australia's NSW beaches remain closed for fifth straight day

Beaches on the coast of Australia 's New South Wales have remained closed for a record fifth straight day as shark sightings in Newcastle, Australia continue to mount.

Four sharks were reportedly spotted at beaches across New South Wales on Tuesday, while the remains of a washed-up dolphin, believed to have been killed by a shark, were also found.

The sightings come as a renowned South Australian shark researcher refuses to disclose information regarding tagged sharks, saying the details will be used to support state governments' catch-and-kill policies.

Andrew Fox, from the Fox Shark Research Foundation, has been monitoring the movements of several species throughout Australia, but says tagging information will be used by state authorities, particularly in Western Australia, to cull potentially dangerous sharks.

Fox told The Guardian on Wednesday that using the data to kill sharks "goes against everything we stand for" and that it was a " complete waste of money, resources and time" to kill a tagged shark.

In Newcastle, the four shark sightings on Tuesday stretched the city's closure of all beaches to a record fifth straight day.

It follows three shark sightings in the three days prior, as local officials attempt to put their finger on the reasons behind such a growing number of sharks in the area.

"There seems to be a lot of life in the water now," local beach inspector Scott Hammerton told The Newcastle Herald on Wednesday.

"The only change in variables is from Friday night to Saturday morning, we had an upwelling and the water temperature dropped from 23 to 18 degrees Celsius (73.4 to 64.4 degrees Fahrenheit) overnight."

"The north-easterly winds pushed surface water down and replaced it with deep water from the south, which is nutrient rich and attracts more sea life."

"The mixing of the warm and the cold water, that's all I can put it down to."

The largest shark sighting of the five-day ban occurred on Tuesday, when water police noticed a four-meter great white at the Burwood Beach in Newcastle.

The police suffered a close encounter, with Hammerton revealing the shark had attacked the police boat with its tail.

"A four-meter great white came up to the police launch, had a look at the boat, flicked its tail and went underneath it," he said on Wednesday.

"It was right on the surface, about 50 meters behind the waves, before heading into the surf zone."

Meanwhile, the death of the dolphin, whose remains were found on Tuesday afternoon, was said to have "definitely" been inflicted by a shark. Endi