of the Fishery Board for Scotland. 



SCIENTIFIC REPORTS. 



13 



I. — ON THE HERRINGS OF THE CLYDE AND OTHER DIS- 

 TRICTS. By H. Chas. Williamson, M.A., D.Sc, F.R.S.E., 

 Marine Laboratory, Aberdeen. 



CONTENTS. 



PAGE. 



Introduction, ......... 13 



Arrangement of Analysis, ....... 14 



List of Contractions, ........ 14 



The Samples of Herrings, ....... 15 



The Weight of the Herring, ....... 50 



The Stage of Development of the Reproductive Organs, ... 54 



The Rate of Growth, ........ 57 



The Spawning Seasons, ........ 65 



Food, . . 65 



Literature, ......... 66 



Additional Samples of Herrings, ...... 67 



In 1905 Dr. Fulton arranged for samples of herrings from the Clyde 

 and other districts to be sent to the Laboratory. They were obtained from 

 commercial fishing vessels. The herrings were in most cases sprinkled 

 with salt, and sent by rail to Aberdeen. On arrival they were in some 

 instances examined immediately; in other cases they were kept in the 

 cold store until required. The fishery officers in the different districts 

 forwarded most of the samples. A large and valuable series of samples 

 was sent by Mr. Johnston and the other officers in the Clyde district. 



The scheme of enquiry drawn up by Dr. Fulton included records of the 

 length and weight of the fish, the sex, weight of the reproductive organs, 

 the sizes of the eggs, and general notes regarding the food, fat, &c. 



In the following pages I give an analysis of all the samples, and also of 

 certain other lots of herrings which were preserved at the Laboratory. 

 Together they make a total of 147 samples. The herrings are classified 

 under the following headings : — (a) Immature, i.e., herrings that have 

 never spawned ; (b) Spawners, i.e., those herrings in which the repro- 

 ductive organs have begun to ripen. They may be recognised several 

 months before they will spawn by the fact that the eggs have 

 begun to show yolk in them. They are sub-divided into winter and 

 summer spawners. (c) Spent herrings. They were further separated 

 into winter and summer spents. The spent is readily recognised immedi- 

 ately after it has spawned, but it becomes more and more difficult to 

 diagnose, as the reproductive organs eventually assume a small, shrunken 

 appearance, which may be confounded with an immature. 



I have taken as a basis the generally-accepted division of herrings into 

 summer and winter spawning groups. As has been pointed out by several 

 writers, the spawning season for each group is an extended one. It would 

 probably be right to make two extra spawning seasons, viz., spring 

 and autumn. While it seems probable that considerable quantities of 

 herrings spawn in the autumn season, it may be that it is really a 

 season of late summer spawners and early winter spawners. During every 

 month of the year some of the herrings in the samples were full herrings, 

 B 



