The Food of Young Clupeoids

Extract

Whilst investigating the food of young fishes in general (Lebour, 1918–1919–1920) some thousands of young Clupeoids were examined, with the result that by far the larger proportion of post-larvæ were found to be empty. Here and there, however, food was present, and by bringing these records of 1917 to 1919 together, with some from 1920 and 1921, we have a good idea of the food of our three common Clupeoids—Herring, Sprat and Pilchard—in their young stages.

A probable reason for this apparent absence of food in the transparent stages is that the food must be very quickly digested on account of its being so conspicuous; thus it is probably taken only at long intervals and rapidly got rid of. It would follow that under these circumstances we should only occasionally catch the fish when food was inside it.

The observations on the food of the young Herring are perhaps the most interesting of the three on account of the fact that it eats solid food some time before the yolk sac is absorbed, the mouth being open when the fish is hatched, whereas the Sprat and Pilchard, being much less advanced, are only able to feed on outside food much nearer the time when the yolk sac disappears. Unfortunately we have no records of Pilchard food in the very young stages (under 12 mm.), green food remains being found in those of the Sprat before the yolk sac has completely disappeared.