HERRING FISHERY OF CANADA 41 



o , _. Experts have found that the concentric rings on the 



Seasonal Rings ^ , • , i • ^.u u * 



of Growth scales of fishes correspond with their growth, out 



in Scales j)^ Hjort, in his study of the west coast Norwegian 



herring, found a great variation in the rate of growth, the most rapid 



being in May, June and July, while growth frequently ceases in winter. 



Hence, when examined under the microscope, broader bands, called 



summer lines, are seen on the scale, while the winter rings appear as 



sharp lines or ridges. Thus the rings or zones of growth on the scale 



show, not only the number of seasons passed by each fish since it was 



hatched, but also the rate of growth during the several periods. An 



instrument has been devised by which the scale is shown enlarged, 



and tangents, drawn parallel to each other and extending to a lateral 



perpendicular, enable the length of the fish to be drawn proportipnately 



for each period of growth. 



^ ., „. The methods adopted and the results are beyond ques- 



of Norwegian tion. In Norway, these methods showed that the 

 Hernng young fry undergoing development in the ova, laid 



on the sandy bottom of the inshore banks off the west coast, escape 

 soon from the eggs and are then carried northward along the coast by 

 the Gulf stream. They spread all along the extensive range of the 

 coast, and, without question, these small fish undergo further develop- 

 ment in northern waters. In the autumn, when they are 8 to 10 

 centimetres (3-2 to 4 inches) in length, and two-thirds of a year old, 

 they begin to make their appearance in the seines. At New Year, 

 they reach a size of 12 to 15 centimetres (4-8 to 6 inches). These are 

 the small herring which are caught along the whole Norwegian coast. 



In the third year they develop an abundance of fat, and remain in 

 this state, mainly in the summer and autumn, till the genital organs 

 develop. This begins from the third year, but, usually, in the fourth 

 or fifth year in the south, and in the fifth and sixth year in the north. 



The mature individuals then separate from the immature, ' fat ' 

 herring, and begin to migrate southwards along the coast till they 

 reach the schools of mature, large herring, with which they intermingle. 



Among these many different sizes of herring:, from 

 Composition , ^ 



of Adult the young fry up to the mature and oldest fish, we find 



Schools several groups, differing either in biological respects, 



or in regard to habitat and manner of life. It is therefore impossible 



with herring to make at any one place, or at any one time, a selection 



from the individuals in the sea, sufficiently representative to reveal 



