The port will remain open to customers while discussions continue.
Captain Calum Grains, Chief Executive, Lerwick Port Authority, said:
“The port will remain operational, with measures in place to minimise any disruption to our customers and the community.”
“It is very disappointing that our latest offer has been rejected without any constructive proposals from Unite. We have offered to move shore staff onto a salaried remuneration to bring them in line with other departments and reduce working hours to improve work life balance as requested.
Regrettably it appears strike action is now inevitable, despite the earlier offers made and our repeated efforts to find a solution which will continue.”