le 
of the basal line to the annual rings, (see Fig. 11, V, 9, and ¢,). By means of an appa- 
ratus, it is then easy to calculate the length of the fish during the different winters*). 
If we now examine, in this manner, a large 
number of herrings of a year class of old, grown 
fish from the spawning shoals (spring herring) these 
being so old that we may suppose all the individuals 
of the year class to have joined the shoal, there is 
every probability of obtaining at any rate an ap- 
proximate picture of the average growth. Ex- 
perience would also appear to indicate that the 
spawning shoals contain herrings which have passed 
their growth at various parts of the coast, which 
would render the resulting average as representative 
as possible. 
Average size of the herring at different ages. 
In a sample of spring herring, examined ın 
1909, a group of ten year old fish was found, 1. e. 
of individuals spawned in 1899. According to the 
measurements, the average growth of these fish had 
been as follows: 
At the age of 
1 year 8.8 cm. 6 years 28.6 cm. 
2 years 12.7 » 7 » SO. » 
3 o> diet» 8 » ali » 
A 22730) 9 » BIL » 
D ) A D 10 » 324 » 
These figures thus express the average size of the spring herrings spawned in 1899 
for each winter of their life. We will here consider them as giving the averages for the 
size of the different age classes in winter. The mean values for summer and autumn 
will of course be between the figures for the previous winter and those for that following. 
Growth at different seasons of the year. 
Lea**) has carried out some interesting investigations regarding the growth of herrings 
at different seasons of the year. His method consisted in measuring, during 16 con- 
secutive months, a large number of individuals of a year class which at the time of com- 
mencing investigations was about two years old. He thus obtained figures expressing 
the average increment of growth for each month in the third year of life. The results 
of his measurements are given in Fig. 12. From this it will be seen that growth took 
place only in the months from April to September. From October to the end of March 
there was no increase at all, which fact also explains the narrowness of the winter rings, 
and their sharply defined contrast to the remainder of the scale. The growth was most 
*) Vide Publ. de Circ. No. 53, p. 37. 
**) Hinar Lea: A Study on the Growth of Herrings, Publ. de Cire, No. 61. Copenhagen 1911. 
3% 
