The 2013 census found 471 people, of 20,826 in the district, identified themselves as Pasifika, but some in the community view that number as ''incredibly low''.
And the district could be losing out on funding, Waitaki newcomers network and migrant support co-ordinator Christine Dorsey said.
''We're really concerned about that census last time that had the inaccurate numbers about the Pasifika community, particularly for the Tongans,'' Mrs Dorsey said.
''We're really trying to work on getting as many Pasifika people as we can to fill [the census] out, we've just got to get that data correct this time.''
Oamaru Pacific Network chairwoman Frances Oakes said when she arrived in Oamaru in 1974 the Tongan community was very small - ''probably two or three people - and I was one of those'' - but now the estimate of 1000 Tongans in town was likely realistic.
''Anecdotally that's the figure that's been talked about, but we do know that Alliance [the Alliance Group's Pukeuri plant] have got several hundred employed, Te Pari [Te Pari Products] is the next one, and then of course, the stats throughout New Zealand talk about how we have higher [numbers of] younger people as well,'' she said.
Many Pasifika schoolchildren attended local schools, she said.
''Now you walk into town and you see people in the supermarkets, you see island names in the rugby clubs - the majority of the rugby clubs have got Pacific Island people - so, yeah, that definitely has changed.''
To help generate Pasifika involvement, the Waitaki District Council created four short videos in English, Tuvaluan, Samoan and Tongan languages, encouraging residents to take part in this year's census, council communications adviser Alena Lynch said.
''To take part, to understand that the information is confidential and private, not shared, and that it is online predominantly - and if they need any help they can get it.''
Yesterday, in a statement, Waitaki District Health Services chairman Chris Swann said information gathered during last year's review of services at Oamaru Hospital showed the district could be missing out on funding due to inaccurate population information.
Staff at Oamaru Library, Waihemo Service Centre/Library, in Palmerston, and the Kurow Community Library could help.
And Literacy North Otago manager Helen Jansen said help would be offered at its Ribble St centre as well.
