— 60 — 



an investigation into the younger stages of the herring during the winter in the 

 waters about the Inverness Firth was carried out in the motor boat "Enid". Oper- 

 ations actually commenced in December 1921 when the sprat and herring fisheries 

 were already in progress. Different methods of fishing were adopted: drift and 

 anchored nets, with considerable range in the size of meshes, were first employed. 

 By this means herring identical with those landed by local fishermen were captured, 

 and in addition, large adult herring ranging in size from 24 to 30 cm. A very small 

 mesh seine net gave the best results insomuch as its action was less selective and 

 thereby better evidence was forthcoming as to the relative numbers of each group 

 or brood present in the Firths. Fishing was also carried on by means of a bag-net, 

 made of Hessian cloth, which was allowed to stream from the boat at anchor in 

 the tideway. This method yielded yet another brood of small unsealed herrings. 

 The net result of the investigations so far shows that at least five distinct 

 groups of herrings were present within the Firths: — 



Approxim. Av. Size. 

 Group I : unsealed 4 cm 



— II: scaled 9 - 



— Ill: — 13 - 



— IV: — 19 - 



— V: — 26 - 



Overlapping in the intermediate sizes was almost negligible. 



Practically all individuals in Group IV were immature fish. A few were 

 found with well-developed reproductive organs. This fact coupled with discrepancies 

 in age-determination according to the scale readings would seem to indicate that 

 this group is not so homogeneous as it looks, but that it is a mixture of Group II 

 and III at a later stage (1 year). 



5. Investigation of the rate of growth at all stages, especially by study of the 

 scales. 



Denmark. 5) Investigations as to the rate of growth of herring have been 

 carried out. 



Finland. 5) Collections of material from the various parts of the Finnish Bay. 



England. 5) A critical examination of the determination of age by scale 

 rings has been commenced, and has yielded provisional conclusions which seem 

 to point to a need for a modification of the usual interpretation of the rings. The 

 rate of growth of the younger stages has been determined by measurements of 

 samples taken at different times of the year. 



Scotland. 5) These methods are under consideration. 



