The aquaculture register was implemented in 2002 and in the first year the quality of the figures was poor. Subsequently the quality has improved considerably. Due to the relatively low number of facilities, it is possible to personally contact facility owners whose data are lacking, incomplete or questionable, striving for high data quality. A wide range of validations are conducted, but most effort is put into validating data on production such as quantity and value.
All owners of aquaculture facilities in Denmark have to fill in the questionnaire. Thus there is full coverage and sampling techniques are not applied to estimate the full population.
The questioner has undergone minor changes over the years, but the biggest was in 2012. Until then data on juveniles were collected in kilos. But since Eurostat asked for figures on juveniles in pieces, and it wasn’t possible to find suitable conversion factors, the questioner was changed to collect data on juveniles in pieces. Not having data on juveniles in kilos caused problems in other instances, and from 2014 data on juveniles have been collected in both kilos and pieces. Hence there is a data break concerning the years 2012 and 2013.
When no weight has been reported for juveniles, the following conversion factors have been used: 0,05g/pcs for Pollan; 0,5g/pcs for Turbot and Flounder; 2g/pcs for Perch and Northern Pike; 10g/pcs for Salmon, Eel and Oyster; 25g/pcs for Sea Trout, Blue Mussel and Brown Trout, and 50g/pcs for the rest.