I 



258 



The Growth-Rings on Herring Scales. 

 By Geoffrey W. Paget, B.A., and Bobert E. Savage, A.R.C.Se. 



(Communicated by Dr. A. T. Masterman, F.R.S. Beceived April 1, 1916.) 



This note summarises the results of certain investigations on this subject 

 carried out in the Laboratory of the Board of Agriculture and Fisheries. 

 The researches of each author were carried out independently, and their full 

 reports will be published in the Fisheries Investigation Series of Beports of 

 the Board. 



The number of scales on Teleostean fish being roughly the same through- 

 out life, it is reasonable to suppose that they follow iu their individual 

 growth the growth of the fish as a whole : that when the fish is growing 

 fast the scales grow at a corresponding rate. This differential growth-rate 

 is clearly shown on those scales which are marked with concentric striations, 

 for in these cases the striae appear closer together when growth is slack than 

 they do when growth is vigorous. 



By means of marking experiments, such as have been conducted with 

 salmon, whereby the age of the fish is definitely noted, the alternate close 

 and open growth exhibited by the striae on the scales have been shown 

 in general to correspond, with some reservations, with the recurring seasons^ 

 of the year. Hence, in this species, it is possible from observations of the 

 scales to determine, in many instances with a high degree of certainty, the 

 age of the fish. The same method has" been applied to other fish, notably 

 the eel, cod, haddock, -carp and herring, with varying success. The last- 

 mentioned species has, in recent years, received particular attention ; a great 

 mass of data has been collected and conclusions of far-reaching importance 

 deduced. 



Between the scales of the salmon and those of the herring, however, a very 

 marked difference exists. Whereas, in the former, the striae are concentric 

 and thus are capable of reflecting by their grouping the rate of enlargement 

 of the scale as a whole, in the herring, on the other hand, as hitherto 

 described, the striae are eccentric, and in many cases run in almost straight 

 lines from side to side across the anterior half of the scale. For this reason 

 no differential grouping of striae can be seen. Instead, at intervals upon the 

 field of the scale, there occur abrupt transparent concentric rings which 

 appear to have no relation whatever with the eccentric striae. It is, never- 

 theless, these rings which are regarded as marking recurring periods 



