Verification of the CMIX procedure on species with known age-length keys

Calculation of age composition of density-at-length data produced during inventory surveys using the method of W.K. de la Mare (1994) is a conventional procedure in the WG-EMM and WG-FSA practice.
Verification of the method was made on the materials on the Baltic cod collected in the ICES Subarea 26. Age-length keys for 1995-2001 and length frequency data obtained during the surveys carried out by research vessels of Russia and other countries were used.
It has been shown that divergence in the estimates of age composition proportions calculated using the CMIX method from those determined from age-length keys (ALK) computed based on the materials of direct age reading may be significant reaching 100 per cent or more. Individually, recruitment estimates also differ considerably from the estimates based on ALK.