Reconstructing reciprocal M vectors from length cohort analysis (LCA) of commercial size frequencies of hake, and fine mesh trawl surveys over the same grounds

Results of length cohort analysis of commercial landings with fine mesh trawls of small hake from Viareggio, Ligurian Sea, are compared with the size frequency of contemporaneous randomized trawl surveys on the fishing grounds of the same port under two assumptions: (1) constant M; (2) M as a reciprocal function of age obtained from an earlier analysis. The second comparison showed a closer relationship between predicted and actual numbers of individuals on the grounds. A third approach used the same two data sets to find a "best fit" for a reciprocal M-at-age relationship of the type previously described by Caddy. This M vector, and the F-at-age values lead to, appear to be more reasonable than those obtained under "constant M" assumptions. (C) 1999 Elsevier Science B.V. All rights reserved.