If no in formation was found to justify clear gaps in a catch series, these were linearly
interpolated .This included missing data in the first years of recorded catch .
For example , if the first four years of a catch series were missing and the fifth was 500 t,the first year was assigned half the value of the fifth (thus assuming the fishery had not grown from zero catch in1950 )and the other years linearly interpolated.
Or, if catch records were missing from, say,1960–1965,these were linearly interpolated from reported catch in1959 and 1966. Interpolated catch was designated as unreported and used as the new baseline for subsequent estimations of unreported catch.