You don't specify what type of records... church records, probate records???
The scanned parish church records on the Digitalarkivet website are created from the microfilms done by the LDS years ago and also available through them still at any LDS Family History Center. Their online library catalog (available at Familysearch.org) gives the following information in the notes under Church Records for Norway, Nordland, Tjøtta.
"Contains parish registers from the parishes Tjøtta with Skålvær chapel and Vevelstad. They were separated from Alstahaug clerical district in 1862. For years 1776 to 1862 see Alstahaug clerical district."
Checking the LDS library catalog is often a very informative and useful tool.