For the past month or so vigilant boat owners have covered most vessels with netting on Oamaru Harbour to keep gulls from roosting.
Without the netting, the birds "make a hell of a mess" North Otago Yacht and Power Boat Club commodore Kevin Murdoch said.
"There are some boats out there that haven’t got anything on them and they’re shocking, they’re a real mess."
White nets had proven to be the most effective in keeping breeding gulls away, Mr Murdoch said.
"We’ve sort of experimented a bit but with the white netting, they can see.
"So, we very seldom get them hooked up or caught in them.
"We do keep an eye to make sure there are no wildlife caught in them."
Netting was used on the boats all year round, but was especially important now due to the breeding season.
"If a boat comes into the harbour, within about two weeks [the seagulls] get used to the boat being there and then all of sudden they’ll start sitting on them."
The boat owners were responsible for paying for their own boats to be netted, Mr Murdoch said.
