An age-structured production model (ASPM) is to be developed for each of the four islands of the Tristan da Cunha group (Tristan, Inaccessible, Nightingale and Gough). The model will be sex-disaggregated as there are substantial differences in growth rates and length at age between the sexes. The model will be fit to CPUE and possibly catch-at-length data. A historic catch series developed for each island will be used. The model will run from 1949 when commercial harvesting first began. The resource will be assumed to be at pristine equilibrium at the start of 1949.