One trader says she has already seem takings fall by nearly half since the P&O sackings,
Sandra Malho, of the La Salle Verte café in Cannon Street, said: "Our takings have gone down by 45% since March 17, both from P&O Ferries staff and passengers.
"We used to be full at lunchtimes.
"There has already been an effect from inflation where fewer people want to even buy a cup of coffee.
"We had also been badly affected by the lockdowns so I don't know if we'll survive this time."
Across the road is the Vinoteq wine bar where the manager, Sam Marlow, was a P&O Ferries steward from 2003 until he took voluntary redundancy in 2020.
He said: "There was a habit of P&O workers coming to town centre pubs during their seven-day-off periods so this may probably affect town centre pubs and bars. But so far our business has not had a direct affect."
Annette Page, manager of The Duchess in Bench Street, saw the pub filled with P&O staff on the day the redundancies were announced.
She said: "They were here together all day. Since then we have not really felt any effect on our business.
"We tend not to get P&O passengers anyway, they are more likely to be cruise terminal ones."
Ryan Smurthwaite, a manager at the Eight Bells in Cannon Street, also said no effects were felt so far.
He said: We do have a few P&O staff as customers so there may be an effect later."
On the seafront Cam Yildiz, assistant manager of the Dover Patrol restaurant and bar, said: "We have had P&O customers but we have not been affected yet.
"But that may happen in the summer as we get a lot of foot passengers then."
John Angell, chairman of the business group Dover Town Team, said: "The loss of 600 jobs in Dover is bound to have a negative effect on trade in the town centre.
"This is another blow for the town following Covid, and the rise in energy and petrol prices, as well as the rises in National insurance and council tax.
"These will all make trade that much more difficult for all retail businesses in the town. It is too early to give an estimate of the effect of these price rises but a negative effect they certainly will have."