Fast-ferry services to Sydney's popular tourist destination of Manly have been cut by about a quarter due to a decline in passengers during off-peak periods of the day.

While the frequency of peak-hour services will be maintained for commuters, the NRMA-owned Manly Fast Ferry has decided to cut off-peak services from Monday, reducing the total number of one-way trips between Circular Quay and Manly from 719 a week to 542.

Manly Fast Ferry has cut weekly services on the Circular Quay-Manly route by about a quarter. Credit:Ben Rushton

Manly Fast Ferry chief executive Richard Ford said the number of passengers on its ferries during off-peak periods of the day over the winter had not been sufficient to sustain all of the services.

"We had been seeing the passenger numbers down this winter. If we are losing money on some of those services, we have to make sure we are flexible with the market," he said. "We are an unsubsidised service, so we rely 100 per cent on revenue from the passengers."