Biosecurity is being stepped up in Northland after the discovery of the Queensland fruit fly in Whangerei earlier this year.
Eight extra quarantine inspectors will be working in the region from October to mid-December when the bulk of yachts sheltering in the Pacific Islands haul anchor for New Zealand or Australia.
The Ministry for Primary Industries' north ports manager said although there is limited evidence to suggest the flies arrived in New Zealand on yachts, they are keen to ensure it doesn't happen.
Sharon Tohovaka said intensive inspections would be carried out, along with the help of detector dogs.
The Navy and Air Force would also ramp up surveillance of yachts approaching New Zealand's coastline with border clearance staff from the Ministry for Primary Industries among crews.
Northland iwi are also being asked to get involved by reporting sightings of any unusual events such as vessels anchoring along the coastline without informing authorities.