31 



The first year growth of herrings with three winter rings 

 was on the whole greater for the fish in the spawning shoals than 

 in tlie feeding shoals for both the Peterhead and Scarborough 

 samples. 



Attention has been drawn to the change which takes place 

 in the shoals throughout the summer feeding, and it w^as stated 

 that these changes were considered to be due to immigrations 

 into the shoals. Whilst changes up to the end of August and 

 early September may be due to immigration, the last change 

 w^hich takes place, and causes fish with a comparatively small 

 first year growth to be so abundant in the samples, may be due 

 to fish leaving the shoals for the purpose of joining a spawning 

 shoal. The first year growth for herrings with three winter rings 

 from the Peterhead samples was as follows : — 



NIMF-ERS AT CENTIMETRES. 



Practically the whole range of first year grow^th is represented 

 in the 32 fish of 9th September, and 30 of them were spents. The 

 figures appear to form two groups, one about 8 and 9 cm., and the 

 other about 12 cm., and point to these fish having originated from 

 both spring and autumn spawners. 



From the grow^th calculations it appears that spring and 

 autumn spawTiers differ from one another as regards growth after 

 reaching maturity. The oldest fish which occur in sufficient 

 numbers in the samples to allow of comparison are those wdth 

 six winter rings in the autumn spa^vning shoals, and those with 

 seven winter rings in the spring spawning shoals of Stornoway 

 and the Shetlands. 



These fish are, except for the date of capture, of the same age, 

 for the sixth winter ring is immediately inside the edge of the scale 

 of the autumn spawners, and in the sj^ring spawners the edge has 

 been counted as the seventh w- inter ring. The maturity data 

 wdll show that the fish can be taken as spring and autumn spawTi- 

 ing fish. The growth attained at the formation of the first and 



