|Further observations on the food of seals|In: Journal of Zoology (1965). Academic Press: London. ISSN 0022-5460, more
Studies of the food of seals on Scottish coasts were continued at the Marine Laboratory from 1967 to 1971. In general the results confirmed those of 1958–66 in stressing the supreme importance of fish, particularly species of economic value, in the food of both the Grey and Common seals. Four families of fish–salmonids, gadoids, clupeoids and pleuronectids– were again prominent in the food of both species of seal although the frequencies with which they appeared in the stomachs varied from one period to another. Grey seals preyed more heavily on salmonids and gadoids and Common seals on gadoids and clupeoids. Changes in the diet of seals from one year to another would appear to arise from the sampling of the seals for examination and to the availability of the species offish preyed upon, depending on seasonal movements and natural fluctuations in their age–groups.