A total of 800 tonnes of sea lettuce has been collected from Tauranga shores in the past week.
The Bay of Plenty Regional Council said it was the first collection for summer.
Regional council technical advisor Bruce Gardner said sea lettuce was natural but could be a nuisance when it washed ashorer.
Mr Garden said Tauranga Harbour's sea temperatures of 15 to 20C meant it was the perfect place for it to grow.
Mr Gardner said that Regional Council's scientists have been checking on sea lettuce growth in the lead up to summer.