Profile analysis of Euphausia superba larvae vertical distribution in the Scotia Sea,related to time factor

Summary The vertical distribution of Euphausia superba larvae caught during the January–February 1981 cruise of BIP Dr Eduardo L Holmberg to the Scotia Sea, was studied by means of the multivariate linear model. The profile analysis technique was applied to vertical distribution of different stages, using a variable composed by counts at each one of the four sampling depths. After the logarithmic transformation of data, this technique showed significantly larger numbers of larvae by night than by daytime in the upper 100 m. No significant differenc was found between 100 to 200 m, which was the lowest level sampled. No vertical migration was observed.Younger larvae distributions suggest that ascending larvae were not present in significant quantities in the whole area. Net avoidance is proposed as the simplest explanation for night — day differences, in view that a supposed migration out of sampling limits in light hours, has no support in present or literature data.