If they were to mimic a scene from the movie Jaws, one of the fishermen might say: "We're going to need a bigger rod."
In a video  that yesterday went viral, a six-foot (1.83m) shark emerges from the sea in Sai Kung to shock two anglers reeling in a fish. The video posted on Facebook shows one of the anglers struggling, with the shark at one stage appearing to grab the fish on his rod as his pal records the extraordinary scene.
Speaking in Cantonese, the two speculate about the size of the shark, saying it looks to be around six feet long.
The video, which had been shared by more than 500 Facebook users as of last night, comes with the caption: "Sharks at Sai Kung! Think before you enter the water!"
It claims the fishermen were somewhere between Sai Kung main pier and Kau Sai Chau island when the shark was seen.
However, shark experts urged swimmers and anglers not to panic saying if it was genuine, then the shark shown in the video posed no risk to humans.
Alex Hofford, director of Hong Kong Shark Foundation, said there was no definite proof the sighting was in Sai Kung and he believed the video may have been circulating for more than a month.
"There is no cause for alarm. In fact if it is genuine then it is probably a good thing," said Hofford. "Hong Kong introduced a ban on bottom trawling from January 1. If this is filmed in Hong Kong then it's a positive sighting. It means Hong Kong waters are getting back to normal after being raped for years by bottom trawling.
"Obviously sharks are wild animals and you should treat them with respect. But anyone seeing something like that should be just amazed and enjoy seeing such a beautiful animal."
Experienced diver and marine conservationist Paul Whitehead, of Eco Marine, a group set up to promote local marine awareness, said there was no reason to suggest the video was a hoax, with sharks common in Hong Kong waters, especially with water temperatures rising.
"If anyone was going to post a hoax they wouldn't use a sandbar shark. They would use a bigger, more dangerous breed of shark," said Whitehead.
"There is nothing to be afraid of with this shark. It is one of the friendly sharks. If divers want to go and see sharks, this is one which is quite happy to have divers around it."
Whitehead said he believed it was a sandbar shark, a harmless species that feeds on crabs and small bony fish and is commonly seen in shallow sandy coastal waters.
"With the bottom-trawling ban, these sharks will start to find interest in the settling of the sediment," he said.
Whitehead said Eco Marine planned to hold several shark awareness presentations at its headquarters free to anyone wishing to learn more about sharks.
A government spokeswoman said it had not received any reports of shark sightings in the Sai Kung area. The last reported shark attacks in Hong Kong were in 1995 when three swimmers died off the Sai Kung peninsula.