Larval blue whiting of 3–42 mm total length, taken in 1967 and 1968 in the Rockall Bank area, were found to have fed almost exclusively on various stages of small crustaceans; the eggs, nauplii and copepodites of copepods, along with fewer numbers of larval euphausiids and Evadne nordmanni, formed the major proportion of the diet. The guts of the larger larvae contained a greater number of, and larger organisms, than those of the smaller larvae. Feeding incidence was generally lower at night. There was a general increase in the weight of the gut contents as the daylight hours progressed followed by a decrease during the night. Diurnal variation in the percentage composition of the food was also demonstrated. Comparisons of the diet in the two years showed that more food was consumed by almost all sizes of larvae in 1968.

It has previously been suggested that blue whiting larvae may find better feeding conditions on Rockall Bank than off the Bank. However the present study suggests that larvae, particularly of 8 mm and longer, took more food when off the Bank. A brief comparison is made of the gut contents of the larvae of blue whiting and of the other eight most abundant species.