"It's possibly the same shark cruising up and down the beach."
He said it was common for sharks to swim about 50m offshore, parallel to the beach and travel up and down the beach.
"They don't hang around, they just keep swimming along," he said.
"They are around all times of the year but at this time we've got a lot more people down on the beach and in the water and with the Rena stuff you've got people talking about sharks, even though that's 15 kilometres away."
Sharks were not generally interested in humans but Mr Smith advised people to get out of the water if they saw one and give it time to move on.
"You've got to be sensible about it. It's commonsense to get out of the water," he said.
Yesterday's sighting did not put people off swimming in the ocean less than an hour afterwards.
Fishing guide and owner of Saltflyer charter fishing company Nikolaj Mathiesen said there was likely to be more sharks in the waters around Rena.
"Rena acts like a huge fish aggregating device [FAD]. FADs are devices used by fishermen to attract fish. It can be anything that is floating, or tethered to the ocean. The fact that the Rena is there as a floating structure means it attracts smaller fish which in turn become bait for sharks," said Mr Mathiesen, who leads shark hunting expeditions in the area.
Great whites are unusual for the Bay, but other shark species are common in the area.
Mr Mathiesen had already seen a hammerhead and two makos this week and said these types of sharks would be typical of the ones around Rena.
Ian Thomas, president of the Tauranga Game Fishing Club, agreed Rena was attracting sharks.
"The growth on the Rena's hull is increasing. It's a mass of metal with growth on which does make it a huge type of fish aggregating device. So the marlin and tuna will be plentiful around Rena and in turn they will be bringing the sharks in," Mr Thomas said.
He rejected reports sharks were attracted to potential food in Rena's remaining containers.
"They wouldn't be able to smell this food unless it spilled into the water," he said.
Charter fisherman Russ Hawkins agreed the sharks are settling in.
"On Tuesday we were seven miles from Rena and saw a mako shark chopping at our fish.
"Last week we saw two mako and a blue shark. The makos and the blue sharks that are commonly seen in these waters are fairly harmless and safe to dive around," Mr Hawkins said.
Volunteer lifeguards have been on patrol for about a month (from 10am-5pm on weekends) but paid lifeguards stationed at the surf clubs from 10am-6pm started on Monday - and this was another reason why shark sightings were more common, Mr Smith said.
"Sitting from the tower you get better sightings than volunteers on the weekends," Mr Smith said.
If a shark or a group of sharks were hanging around near the flags, lifeguards could close the beach for an hour or two.
Mr Smith encouraged the public to phone in with shark sightings as it gave them valuable information.
"It gives us an idea of what's happening and it's really great to get that information," he said.
