Unionized workers at four Sheraton hotels in Waikiki participated in a one-day strike picket Friday at the properties over a plan by the hotels’ owner to outsource concierge staff work.

The union representing the workers, Unite Here Local 5, estimated that 2,300 of the 2,400 workers it represents at the four hotels — Royal Hawaiian, Moana Surfrider, Sheraton Waikiki and Sheraton Princess Kaiulani — honored a strike called by 10 concierge workers at the Royal Hawaiian.

Paola Rodelas, Local 5 spokeswoman, said the owner of the four properties, Kyo-ya Hotels &Resorts, in October responded to an effort by about 50 concierge workers at the four hotels to consider unionizing by announcing it would subcontract those jobs to local activities company Pleasant Holidays as of Feb. 1.

Rodelas said 10 of 11 concierge workers at the Royal Hawaiian decided to strike over the issue, but that the support from nearly all other unionized workers at the four hotels sends a message.

“We think that we sent a really strong united message that subcontracting destroys jobs and impacts families,” she said.

Kyo-ya issued a statement Friday saying that it decided last summer after a careful review to provide its concierge, activities and dining services through a partner, and that Pleasant Holidays committed to taking care of the hotel employees and elevate the range of activities for hotel guests.

“Like other hotels in Hawaii and across the nation, it is common industry practice to rely on partners to provide such services,” the company said.

Kyo-ya said it offered the 42 affected employees guaranteed work with Pleasant Holidays for at least two years and with greater compensation. As an alternative, those employees also could transfer to a vacant position within Kyo-ya or accept a severance package.