28 



that these fish are some six iiionths younger. They have their 

 third winter ring at the edge of the scale, and the others have a 

 summer zone of growth between the third winter ring and the 

 edge of the scale. 



Both the sample of 9th March, 1920, and that of 23rd 

 September, 1919, contained fish which were not actually spawning. 

 The March sample had 51 fish at stages VI., VII. and VII.— II., 

 and the September sample had 37 fish, which were spents. These 

 fish were spring and autumn spawners, and their first year growth 

 was as follows : — 



LUMBERS AT CENTIMETRES. 



Date. 



9/3/20 ... 

 23/9/19 



This first year growth is so scattered that if the period between 

 hatching and the formation of the first winter ring be considered 

 the chief factor in determining the first year growth, we have 

 spring spa^^^lers arising from the young of both spring and autumn 

 spa^\^ners, and autumn spawners arising in the same way. 



Very few fish younger than those under consideration have 

 been found actualh' spa^^^ling, and these are the youngest spa Nailing 

 fish in sufficient numbers in the samples to allow of comparison. 

 The fish spawning at the time when the third winter ring is at 

 the edge of the scale have, on the whole, a greater first year growth 

 than those in the September sample. They are younger fish, 

 and are probabh^ made up of a large number of fish born in the 

 autumn, and a small number, which have had a great potentiality 

 for growth and early development, born in spring. That is, the 

 majority are about three-and-a-half years old, and the remainder 

 three years old. It has been pointed out that it is considered 

 autumn born fish do not form their first winter ring at the end 

 of the year of birth. In the September sample the fish are older 

 by some six months, the third winter ring being inside the edge 

 of the scale, and from the first year growth consist of indi^^duals 

 three-and-a-half j^ears old, those with the smallest first year growth, 

 and four years old. 



Older groups of fish, Avith more than three winter rings on 

 their scales, probably contain individuals which have joined the 

 spaAMiing shoals in different j^ears, and which have spa\Mied more 



