Release and recapture data relating to cod tagged and released in the North
Sea (ICES Subarea 4). Between 1961 and 2015, a total of 22,573 cod were tagged
and released using either conventional marker-ID tags and in the more recent
years of the dataset, electronic data storage tags (DSTs), of which 6,703 tags
were subsequently returned. For tagged fish that were recaptured as much
information as possible was recorded, namely the recapture date and location,
length, weight, sex and maturity. Otoliths (ear stones) were removed for age
determination purposes and other studies. These data are used to provide
information for studies relating to fish behaviour, growth and identification
of stock units.