Within the Deep / Cassell's "Eyes and No Eyes" Series, Book VIII.

THE HERRING FLEET AT WORK IN THE NORTH SEA (missing)
A GARDEN IN THE SEA (missing)
Eighth Book

Of all the fish in the wide ocean world, the Herring deserves to be called the king. He gives work to thousands of people, and food to millions. Many towns exist because of him; if he failed to visit our seas, these big towns would shrink to tiny villages.
There are several interesting kinds of Herring, but we will first look at the one we know so well, which is such good food, either fresh or as dried kipper or bloater.
The Herring loves to swim in a shoal . From the time he leaves the egg, during his babyhood, and all through his life, he explores the sea with thousands of other Herrings crowded round him. His name is from a foreign word-- heer or herr , an army . His enemies--ourselves among them--find this habit of his a good one. It makes him such easy prey.
Here is a dense shoal of fish, moving slowly along near the surface. To catch some is quite easy. The Dolphin, or Shark, or other large fish-hunter, merely has to rush into their ranks with wide-open mouth. Hordes of Dog-fish feast on the edges of the shoal. And Gannets, Cormorants, Gulls and other sea-birds can take their fill with ease.
The Herring shoal is a banquet at which the fish-eating sea creatures feed heartily, and man comes along, to spread his nets in the path of the shoal. But what matter a few million Herrings when the sea is packed with billions more! In the North Sea, one shoal was seen which was over four miles long and two miles wide. In such a mass there would be, at the very least, twenty thousand million Herring; and this shoal was but one out of many thousand shoals. One might as well try to count the grains of sand on the shore as the Herrings in the wide ocean.
These huge shoals do not stay long in one part of the sea. They make journeys of many miles, each shoal seeming to keep to itself. Like every other creature, the Herring goes where his food is. What food does he find? He swallows the small life of the sea, tiny transparent things like baby shrimps, prawns, crabs, and so on, which swarm even in the cold water which the Herring loves.