34 



After maturity is reached the summer feeding of the herring is 

 responsible for not only growth in length but also the develop- 

 ment of the gonads. In the autumn spa^\^ling fish the gonads 

 are fully developed by the end of August, when spawning may take 

 j)lace, or in early September. In spring spawning fish the gonads 

 are not fully developed until some six months later, and a con- 

 siderable amount of the material needed for their development 

 may be derived from the tissues of the bod^^ 



The data here given is considered to indicate that spa^vning 

 for the fourth, fifth and sixth years takes place annually. 



The growth made by the fish of the Stornoway sample of 

 27th May is greater on the whole than the growth of fish of similar 

 age found in the autumn spawning shoal, and i)oints to the greater 

 portion of the May sample consisting of fish recovering from a 

 spring spa wiling. The Shetland sample of 28th May is different 

 from the spring spawning samples as regards growth, and appears 

 to consist as far as the older fish are concerned of herrings which 

 are autumn spawners. These differences are most noticeable 

 frojn a comparisoii of the fifth year growth, which will be found 

 in Table III. 



The samples from the north coast of Sutherland have, for 

 fish with six winter rings, a growth which up to the fifth year 

 increases like that of the spring spawners of Stornoway and the 

 Shetlands. There is a small difference between the Stornoway 

 and the Lerwick samples, the latter being slightl}^ larger fish for 

 their age, and the samples from the north coast of Sutherland 

 are nearer in growth to the Shetland fish. Whether a difference 

 w^ould be found to exist for these shoals w^ere an examination of 

 them made th^'oughout the wdnter fishery cannot be said, but 

 there is a possibility of the shoals of the Shetlands and the north 

 coast of Sutherland being more oceanic in habitat than those of 

 the Stornoway area, W'here the Minch affords a large feeding ground. 

 From the growth data here given and Avhat is already known 

 from Hjort's* samples there is sufficient evidence to show that 

 oceanic life gives a greater and quicker growth than does life in 

 the waters of narrow seas such as the southern part of the North 

 Sea. See also page 83. 



* Pub. de Circ. No. 53. 



