Vertical distribution and abundance of the Peruvian anchovy, Engraulis ringens, and sardine, Sardinops sagax, larvae during November 1977

Abstract

Horizontal samples taken with the BIONESS at various depths on 13 stations within 115 km of the coast of Peru showed nine species of fish larvae present with the most common of these being, in order of abundance, Leuroglossus stilbius, Sardinops sagax, Diogenichthys laternatus, Merluccius gayi and Engraulis ringens. All the species except S. sagax and E. ringens showed a diurnal migration to the upper 30 m of water at night. The two above species were present in the top 30 m at all times. The size of the larvae of all species did not vary with time, depth or sample location. The numbers of larvae increased with zooplankton m−3 up to 1000 copepods m−3 above which no further increase in larvae occurred. A significant linear relationship was found between the total number of larvae m−2 and biomass and zooplankton m−2, but not between individual species of larvae and zooplankton biomass. Significant correlations were found between E. ringens and seven species of copepods found in the upper 50 m of water.Polymodal analysis showed that the larval populations of all species, with the possible exception of S. sagax, were made up of more than one sub‐population. From this analysis the length of the spawning season forE. ringens was estimated at 54–68 days.A significant correlation was found between the numbers of E. ringens larvae m−2 and the maximum concentration of chlorophyll α, as measured with Batfish, in the area of the BIONESS stations. This showed the largest numbers of larvae in areas of the highest chlorophyll concentrations.