Growth of North Alboran Sea sardine larvae estimated by otolith microstructure, nucleic acids and protein content

Abstract

Wet mass and DNA, RNA and protein content increased significantly with standard length (LS) of sardine Sardina pilchardus larvae, collected in January 1995, in the Bay of Málaga, North Alboran Sea. LS, wet mass and DNA, RNA and protein content were closely related allometrically to otolith radius (R). Larval daily length increments decreased but DNA, protein and wet mass daily increments increased with larval age. Daily length increments showed a negative and poor relationship with long‐term otolith growth. In contrast, DNA, protein and wet mass daily increments were positively correlated. Differences between observed and back‐calculated otolith radius‐at‐age indicated that larvae with slow otolith growth were under represented in older age groups, suggesting the existence of growth‐selective mortality. Recent otolith growth, estimated from the mean widths of the last six increments, increased with age and R. Individual RNA: DNA and protein: DNA ratios were correlated significantly, although weakly, with LS and larval growth.