164 ADULT HEKEINGS 



Scale Reading 



Mr. Broch was the first to investigate and describe the theory 

 that herring-scales were marked with rings which made it 

 possible to tell the age of the fish and other important facts 

 in its Hfe-history. The scales of the Norse spring herring, for 

 instance, show that the fish grow regularly up to the fourth or 

 fifth year ; from that time the scale grows much more slowly, 

 and from eight to twelve years old the ' winter rmgs ' are closer 

 and closer together ; and it has been found that many thou- 

 sands of scales examined all showed the same type. These 

 herrings are caught during their spawning season from January 

 to April. Some of their progeny are carried into the fjords and 

 apparently remain on the north coast. At any rate, in the 

 fjords is caught all the year round a very small herring known 

 to fishermen as a ' fjord herring ', and it is known that it comes 

 from the big spawning ground on the south-west coast of 

 Norway. These fish, although they belong to the same ' race ' 

 as the spring fish, stop growing a year or two earher. 



Autumn Spawning 



Then the scales of the ' Shetland ' herring grow continuously 

 for eighteen months before the first dark ring is formed. They 

 are hatched out in July or August, and their babies apparently 

 continue to feed steadily through the first winter. In their 

 second winter (when they are 1| years old) they go ofT their 

 feed, and the first winter ring forms. So these herrings have 

 a relatively large first-year scale, and the same thing is true of 

 the Skagerrak herrings, which also spawn in the summer. This 

 being known, it becomes possible to take a catch made (say) on 

 the Viking Bank, or off Lowestoft, and say at once that it was 

 composed of x per cent, of spring fish, and x per cent, of autumn 

 fish ; and when the scales of herring taken from drift-nets all 

 over the seas are compared, it will, Hjort says, be possible to 

 trace the wanderings and distribution of the different shoals 

 with extraordinary accuracy. 



Even off Lowestoft both spring and autumn spawners are 

 caught. There is found, in addition to the Dogger Bank herring, 

 which spawns in the summer and autumn, a small variety which 

 does not grow to more than 9J inches, and spawns when it is 

 three or four years old. This has a relatively small first-year 

 scale growth and a relatively big one in the second year, after 

 which the growth steadily decreases. It is therefore hatched in 

 the spring, and (^uite distinct from the ' Dogger ' herring. 



