142 The Ottawa Naturalist. [Jan. 



abound along the whole coast, increasing towards the north 

 (Nordland and Tromso). Study of the scales proves that the 

 large and spawning herring are four to eight years old, some 

 being even sixteen to eighteen years old, while the "fat" her- 

 ring, as Professor G. O. Sars long ago opined, are two to four 

 years old, some being one year, while others are six to seven 

 years old. To determine the age-composition of the whole 

 herring tribe along the Norse coasts, the proportions of small, 

 of fat, of large and of spring herring would require to be ascer- 

 tained, but science has found a far more neady and easy wav. 

 Dr. Hjort stated that 15,000 examples of herring had been 

 carefully examined in one year (1910), and it was found that in 

 successive years, the fish of one year predominated. Thus the 

 herring hatched, in 1904, exceeded other year-classes, in 1907 

 (as three-year olds), in 1908 (as four-year-olds): but in 1909 

 and 1910, they formed a less predominant portion of the "fat" 

 herring schools: because they had joined the large and spring 

 herring schools and covdd still be identified by their scales. 

 Indeed in 1911, they formed, as seven-year-olds, 70% of the 

 large herring schools. 1904 must have been a more favourable 

 year, for the herring spawning and hatching, than the years 

 before and after. The 1899 year class, being eight-year-olds, 

 in 1907, were traced through 1907, 1908 and 1909 among both 

 the large herring and the spring herring, and were far more 

 abundant than the older and younger year-classes in the same 

 schools. 



These researches have shown that it is possible to ascertain 

 how numerous the year classes are in relation to each other in 

 successive years, if the specimens be sufficiently numerous to be 

 representative. The schools live under such diverse conditions 

 in the waters from 58° to 71" North Latitude, that the rate of 

 growth locally differs. The growth each year being shown by 

 the rings upon the scales, a broad ring means rapid, favourable 

 growth, a narrow ring means less favourable growth, and local 

 races are recognized by special year rings, either broad or 

 narrow. 1904 herring taken in 1909 show five rings, the first, 

 second and third year rings being fairly equal : but the fourth 

 and fifth are very narrow in some samples: but in others, the 

 third-year ring is narrow. Thus these two types (representing 

 local schools) of the same vear can be recognized with facility. 

 The latter arc of "Nordland" origin, and migrated south to 

 join the southern 1904 schools, of which they formed 26%. 

 Results of a similar character are shown by the study of the cod, 

 the age and local origin being shown by the study of the scales, 

 and a key is thus afforded to the growth, migration and dis- 

 tribution of valuable food fish. 



