n6 MARVELS OF FISH LIFE 



The young plaice are now nearly an inch in length, 

 and gradually make their way toward the shore. Thou- 

 sands may be caught in a shrimp net, and they are 

 abundant in the pools left on the sandy shore by the re- 

 ceding tide. The subsequent rate of growth, as in all fish, 

 depends upon the food supply ; for example, plaice grow 

 much more rapidly on the Dogger Bank than on plaice 

 grounds near the coast. As a fair average, a plaice is 

 about three inches in length at the end of its first year, 

 and in each successive year adds from two to three 

 inches to its length until it is five years old, after which 

 time the growth is not quite so rapid. 



Plaice usually spawn when five or six years old, 

 i.e. when they are from thirteen to fifteen inches in 

 length. To know exactly at what age a fish spawns 

 is of importance, for in the distant future, when 

 sound legislation husbands our sea fisheries, it will 

 be illegal to offer a fish for food supply until it has 

 had opportunity of maintaining the continuance of 

 its race. 



We have seen how the exact age of the salmon can 

 be read by the rings of growth on its scales. The age 

 of the plaice and other fish can be told by certain light 

 and dark rings seen upon the ear stones or otoliths in 

 the skull of the fish. Looking at the illustrations of 

 otoliths it will be seen that there is a central white 

 portion which indicates the growth of the otolith during 

 the first spring and summer in the life of the fish. The 

 autumn and winter growth is then indicated by a dark 



