i6 INTRODUCTORY 



for the last thirty years or more, making a total 

 of some 5,000 herrings. This sounds somewhat 

 alarming, but as the average roe of a full-grown 

 female herring contains about 35,000 eggs, 

 human consumption is not likely to overtake 

 the fecundity of the fish, even if half the 

 population were to follow my example. In 

 1881 Professor Huxley stated at Norwich that 

 2,500,000,000 herrings were taken out of the 

 North Sea and the Atlantic every year, and that 

 over 500,000,000 herrings are contained in one 

 square mile of one of the many shoals which 

 approach not only the coasts of Britain, but 

 also those of Scandinavia and the Baltic, and 

 of Eastern North America, every spring and 

 autumn. A shoal usually covers half a dozen 

 square miles, though it may be very much 

 larger ; it is often eight or nine miles in 

 length, three or four miles in breadth, and of 

 unknown depth, the fish being closely packed 

 like sheep in a flock moving along a country 

 lane. Allowing about a cubic foot of space for 

 each fish, we may get an idea of the size of such 

 a shoal by imagining an area in London 

 extending from the Albert Memorial to the 

 Tower, and from Westminster Bridge to the 

 Zoological Gardens, entirely covered with her- 

 rings, swimming, in compact formation, on one 

 of those migrations which baffle understanding. 

 The search for food is not the complete explana- 

 tion. Well might Huxley say that the sum 

 total of the herrings that inhabit our seas 



