Rational approach to development of annual TAC forecasts for medium and long lived fishes
Dynamics of long-living fish stocks is rather conservative thanks to a complex age-size structure of them. It practically excludes sharp interannual fluctuations of the biomass stocks and consequently the recommended TAC. This circumstance allows to redistribute annually efforts of TAC assessment for each stock, alternating a labor-consuming comprehensive assessment procedure with simplified intermediate methods. Intermediate methods of TAC assessment are essentially easier and faster to execute than full procedures. They are based on estimation of tendencies in the biomass stock during some short period before the year of forecast. An interval between two neighbour full assessments depends on features of the stock dynamics, current state, and trade value, and usually doesn't exceed two or three years. The approach is especially effective when a total number of stocks estimated according to this scheme doesn't exceed 5-6 units. The further increase in quantity of estimated stocks makes advantage of this approach less appreciable.